The glaucomas in aphakia and pseudophakia

SURVEY OF OPHTHALMOLOGY VOLUME

MAJOR

36 - NUMBER 2. SEPTEMBER-OCTOBER

1991

REVIEW

The Glaucomas in Aphakia and Pseudophakia KARIM

F. TOMEY,

M.D., AND CARLO

E. TRAVERSO,

M.D.

King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia

Abstract. Intraocular pressure may become temporarily or permanently elevated at various intervals following cataract surgery. There are several mechanisms by which glaucoma develops as a complication of the cataract extraction itself. The presence of a pseudophakos may or may not contribute to the pathogenesis. Important diagnostic clues include the anterior chamber depth, the presence or absence ofan iridectomy, gonioscopic findings, and the appearance of the optic nerve head. Life-long medical treatment is frequently justified, as alternative laser or surgical modalities may not be successful. The exact causes for high failure offiltration surgery in aphakic eyes is not clearly understood; scarring of the conjunctiva, the vitreous, and altered characteristics of the aqueous humor have all been incriminated. Current research to improve surgical success includes the development of effective artificial drainage implants or the use of pharmacologic modulators of wound healing, which promote filtration by preventing scar formation. (Surv Ophthalmol 36:79-l 12, 1991)

glaucoma in aphakiaipseudophakia pressure pseudophakia l

l

l

Transient

or

permanent

intraocular

tion postoperatively have become much higher than during the previous eras when larger suture material was used, often leading to microleaks and hypotony. 175.2:~4.‘?45.28l.?H:~.:~l9,:~L’S Bettman in 196936 analyzed 84 eyes that were enucleated because of complicated cataract extraction; glaucoma was the cause of enucleation in 35 eyes (42%). Kern17” reported postoperative IOP elevation to 25 mm Hg or higher in 2%) of iridocapsular implants and in 4% of iris-clip intraocular lenses. In 1954, Blodi4” surveyed 150 eyes that had to be enucleated after cataract extraction over a 12-year period. Secondary glaucoma was the most common cause (35%) for enucleation, and this occurred with the same frequency following intracapsular cataract extraction (ICCE) as after extracapsular cataract extraction (ECCE). A similar rate (31%) of secondary glaucoma in eyes enucleated after cataract extraction was cited by Blodi in a later report in

pressure

occurs in aphakic and pseudophakit eyes as a result of one of several mechanisms, or it can be due to a combination of several causative factors. Hence, the use of the term “aphakic glaucodi scoura ged,“‘,IOZ,‘60.?09.‘““.27I.“72. ma” is generally ~~~~~~~~~ because it implies that the state of aphakia as such is the only cause for glaucoma; clinically, this is not the case. Throughout this article, we will always be referring to a group of disorders which we like to call “the glaucomas in aphakia and pseudophakia.” (IOP)

elevation

I. Incidence Duke-Elder’” reported the incidence of glaucoma following cataract extraction to be up to 12%, while, according to a review by Francois,“’ incidence ranged from 0.7% to 7%. Over the years incidence has varied because of changes and improvements in microsurgical techniques. Currently, with meticulous closure of cataract incisions,g”gv”‘3 the chances of developing transient or permanent IOP eleva-

1965,“’ where he analyzed 251 eyes. Again, was no difference between ICCE and ECCE. 79

there In an

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36 (2) September-October

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TOMEY,

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more of several mechanisms.“’ Frequently, a comanalysis of 333 eyes enucleated after cataract extracbination of factors comes into play to produce tion, Payne et al 263found that uveitis with secondary chronic, irreversible pressure elevation.Ms160 The glaucoma was the most common cause for enucleavarious mechanisms by which glaucoma occurs in tion (15 1 eyes), and the second most common was epithelial downgrowth (60 eyes). Schulze et a13” aphakic and pseudophakic eyes and the role of intraocular lenses in causing glaucoma have been noted a 32% incidence of glaucoma in 100 eyes ensummarized by Alpar’ and Cashwell and Reed,63 ucleated after cataract extraction, and this also constituted the most common cause for enucleation in and reviewed extensively by Apple et alI4 this group. In this review, we will discuss the possible mechanisms that could produce the glaucomas in aphakia Cinotti and Jacobson 74 found an incidence of and pseudophakia, outline the essentials of diagno5.4% secondary glaucoma after ICCE and 7.5% sis, and evaluate the efficacy of the various modaliafter ECCE. Hoskins’5’ analyzed 3597 eyes with ties of medical, laser, and surgical treatment. Speanterior chamber intraocular lenses and 2703 with cial emphasis will be placed on recent advances in posterior chamber lenses, and found an incidence surgical treatment, including artificial drainage imof secondary glaucoma of 5.5% in the former plants and pharmacologic modulation of wound group, as opposed to only 1.6% in the latter. He also healing in filtering surgery. noted that aphakic eyes required filtering surgery much more frequently (18%) than pseudophakic eyes (5%). Tennant362 reported that secondary glauII. Mechanisms of Pressure Elevation coma did not develop in any of 197 eyes implanted with Choyce Mark VIII anterior chamber lenses, A. OPEN-ANGLE with ICCE, ECCE, or even as secondary implants. 1. Early Post-operative Period/Reversible, In otherwise normal eyes, the incidence of glauSelf-limited coma following cataract extraction alone222*304~3g0 or with intraocular lens implantation’86~‘8g~1g6~278~304~ a. Alphachymotrypsin 336,3gohas not been found to be unduly high, alIn the era of ICCE, alphachymotrypsin-induced though it may be somewhat higher with iris-plane glaucoma, also referred to as “enzyme glaucowas cOmmOn 49,94,102,110,115,161,176,177,185,195,209,218. or anterior chamber lenses.40’ No relationship has , ma,“323 245,251,256.27l.272323,379 occurring in up to 72% ofcases.l763 been found between the initial IOP and the postoperative pressure rise following ECCE and intraocu*“,*‘* It seemed to occur with nearly the same frelar lens implantation.37” Also in eyes with preexistquency in glaucomatous eyes as in normals.‘20 ing glaucoma, cataract extraction, with or without Skalka332 found a lower incidence of glaucoma with intraocular lens implantation, does not seem to adenzyme use than without in non-diabetic patients, versely affect 10p COntr0~~'5,93,130,~~~,1~~.20',22',Z39,2~8, but the reverse was true of diabetics. The onset of 336,36'However, Savage et a1304found that eyes with IOP rise is usually within 48 hours postoperatively, preexisting primary open-angle glaucoma were at and may last for days or occasionally weeks thereocson166 after 28,209,218,251,271,272 higher risk of postoperative IOP rise than nonglaufound no long-lasting J comatous eyes, as did McGuigan et al,225 whereas effect of alphachymotrypsin on the outflow chaneyes with primary angle-closure glaucoma prenels (by tonography and gonioscopy) two and four viously controlled by iridectomy or iridotomy bemonths postoperatively. haved like nonglaucomatous eyes. The presence or The exact mechanism of enzyme glaucoma is not absence of a posterior chamber intraocular lens did clearly understood, but impairment of outflow fanot influence the postoperative IOP rise in medicalcility has been demonstrated by tonography.“’ Anily- or laser-controlled glaucomatous eyes, nor in mal experiments have shown that the enzyme nonglaucomatous eyes. breaks down the zonular fibers into 1000 A fragFollowing cataract extraction, with or without inments, which occlude the trabecular openings.gB’O, traocular lens implantation, IOP may start rising at 7’*2o5Zonular fragmentation was also confirmed in any stage in the postoperative period, although in human eyes by scanning electron microscopy.400 some glaucomatous eyes IOP control does not seem Other theories include a direct toxic effect of the to be adversely affected,75,175,244 and may even imenzyme itself or the solvent on the trabecular meshprove. The pressure rise may be temporary or perwork or on the ciliary body, as well as a possible manent,323 depending on the underlying mechaenzyme-induced inflammatory reaction.202~27’*272 nism. The presence of an intraocular lens does not Several preventive and therapeutic measures have necessarily play a role in pressure elevation,175~293~38’ been proposed to minimize the IOP rise with alphabut in some situations it does initiate and/or aggrachymotrypsin.27L~72 These include the use of a vate the process of secondary glaucoma by one or smaller volume2’~‘02~‘78~245~332 and/or a weaker con-

GLAUCOMAS

IN APHAKIA

AND PSEUDOPHAKIA

centration of the enzyme (1: 10,000 instead of irrigation of the 1: SOOO),I6I,245*271,?72,33? thorough enzyme solution before delivery of the cataract,2”22’ “71,272although experiments in rabbits show that the enzyme is readily deactivated by anti-chymotrypsin activity within the eye,“’ intracameral acetylcholine intraoperatively,” topical timolo13” 4g~pog3p2 or pilocarpine177~209~Z56 at the end of surgery, and oral acetazolamide postoperatively.2’~20g~256Antihistamine and corticosteroids given systemically have been advocated in one report;” however, there have been other contradictory reports regarding the efficacy of these agents. Topical steroids in one report”’ were not found to be helpful. Lantz and Quigley’g5 found no benefiit from preoperative or postoperative acetazolamide treatment, nor from preoperative mannitol, postoperative pilocarpine, or topical or periocular corticosteroids. Beidner et ap8 also did not find any benefit from acetazolamide prophylaxis. Bloomfield4” reported a similar lack of effect of postoperative acetazolamide, and also found no benefit from pilocarpine or subconjunctival corticosteroids, or from more cornea1 placement of the cataract incision.

b. Blood or Other Particulate

Material

The trabecular meshwork may become temporarily occluded by particulate material such as 63.153~161~329~3~9,381inflam_ blood, ?09,?51.270-?72.3?3 pigment, matory debris,‘7’,272.283.3’3 retained cortical material 101.161.175.197,271,272.979~379~36l or any combination of , these64.94

(Fig. 1). Pigment dispersion with secondary glaucoma has been reported with iris-supported,lg as well as with posterior chamber, intraocular lenses,“J~‘“3~301~337~9gg and with pseudophakic cornea1 transplantation.‘55 Jaffe”’ noted that progressive iris atrophy and pigment dispersion with intraocular lenses was observed especially in diabetics. Intraocular pressure elevation under these circumstances is usually self-limited, unless a significant amount of debris is present in the anterior chamber and spontaneous resorption is delayed, in which case surgical evacuation becomes necessary.27”7’ Glaucoma caused by hyphema is usually self-limited, since the blood is eventually absorbed spontaneously. Medical treatment of the secondary glaucoma should be relied on as much as possible until the situation improves.‘7’.‘7’ In cases of intractable glaucoma and/or with impending cornea1 blood staining, surgical evacuation becomes indicated.27’.‘72 In the event of recurrence of the bleeding, laser photocoagulation of the bleeding site has been recommended,‘71:= but in actual clinical situations, it is often difficult to locate and visualize the offending blood vessel.

Fig. 2. causing

Diffuse hyphema following cataract secondary open-angle glaucoma.

extraction,

c. Viscoelastic Substances With the widespread use of viscoelastic substances today, sodium hyaluronate is well recognized as a culprit responsible for postoperative IOP elevation 6,3H~39,119,161,175.?53,455,260~6fi.~7?.379,3X1especially in eyes with impaired aqueous outflow.‘“0S7?.“7” Therefore, evacuation of sodium hyaluronate at the end of cataract operations has become almost routine practice among ophthalmic microsurgeons, 72~‘47.p53*579 although some find it unnecessary. ‘49,‘5”A new, less viscous formulation of sodium hyaluronate has been reported to decrease drastically this side-effect.““.344 Glasser et al”” demonstrated the beneficial effect of anterior chamber washout in minimizing postoperative IOP rise with 1% and 3% sodium hyaluronate, chondroitin sulfate, and methylcellulose. Sodium hyaluronate has been shown to be 20 times more viscous than chondroitin-6-sulfate,‘g4 which in animal experiments was found not to cause IOP elevation.“” On the other hand, Mac Rae et al”’ demonstrated a sharp increase in IOP in animals with 1% sodium hyaluronate and with 20% chondroitin sulfate, and to a lesser extent with 10% chondroitin sulfate and 0.4% methylcellulose; pressure elevation was less when these substances were washed out of the anterior chamber. Viscoat@, which is a mixture of sodium hyaluronate and sodium chondroitin sulfate, was also found to cause IOP elevation after ECCE and IOL implantation, even when aspirated from the anterior chamber at the end of the procedure.“’ Passo et al’“” used sodium hyaluronate to reform the anterior chamber after IKE and demonstrated a maximum IOP rise 16 hours after surgery; acetazolamide was not helpful in preventing this pressure rise. Naeser et alTb7also found that acetazolamide did not prevent the IOP rise caused by sodium hyaluronate, even when the latter was aspi-

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Surv Ophthalmol

36 (2) September-October

rated at the end of surgery. On the other hand, Lewen and Insler203 recommended the prophylactic use of acetazolamide following posterior chamber lens implantation using sodium hyaluronate. Pape and Balazs 257found that sodium hyaluronate did not necessarily raise the IOP unless it became mixed with blood, cortical remnants, or enzyme digest. They recommended the prophylactic use of timolol and methazolamide. Percival’@j recommended similar prophylaxis using timolol and/or acetazolamide. Hein et a1134suggested that the use of hyaluronidase, based on animal experiments, may be useful in preventing the hypertensive response to sodium hyaluronate by breaking it down into smaller molecules. Aron-Rosa et al in 198315 reported no significant IOP rise in a group of eyes where 1% methylcellulose was used (and washed out) with posterior chamber intraocular lens implantation. Berson et al,35 on the other hand, demonstrated a 65% decrease in outflow facility by intracameral sodium hyaluronate in enucleated human eyes, and this was not improved even after thorough, vigorous irrigation, except when hyaluronidase was used with irrigation. A thorough review of the various viscoelastic substances was published recently by Liesegang.*‘” In the event that a filtering operation is performed simultaneously with lens implantation, we have tended to leave all or part of the sodium hyaluronate inside the anterior chamber. The presence of a viscoelastic substance seems to safeguard against pseudophakos-endothelium touch in the immediate postoperative periood, should there be shallowing or flattening of the anterior chamber. Regardless of whether or not a filtering operation is performed with cataract extraction, we routinely put all patients on acetazolamide immediately postoperatively until IOP can be measured. We believe that the potential benefit from using such prophylactic treatment far outweighs any possible side-effects, especially in cases with advanced optic nerve damage, where an IOP rise of any magnitude may be serious. In such cases we make sure that all of the viscoelastic substance is aspirated at the end of surgery, even with simultaneous filtration, where we normally like to keep the viscoelastic substance for reasons mentioned earlier. d. Idiopathic Intraocular pressure may still rise following cataract extraction without any detectable cause.‘26,185, 4og*283Such idiopathic IOP elevation has been reported in up to 23% of routine cataract extractions, without the use of alphachymotrypsin or viscoelastic substances.‘60,‘75 Pressure rise usually starts with-

1991

TOMEY,

TRAVERSO

in hours after surgery and may last for weeks thereafter.‘26~20g~245~247 It has been reported to be less with clear-cornea cataract incisions than with the limbal approach, 293 although there has been another report to the contrary. ‘*’ Gross et al’*” found a higher incidence of IOP rise after ECCE with intraocular lens implantation than with phacoemulsification and intraocular lens implantation. Hollands et a1148 reported significantly lower IOP in eyes treated with intracameral acetylcholine during ECCE with intraocular lens implantation, and this effect was significant up to six hours postoperatively, but much less so at 9 and 24 hours. Roberts’*’ reported three cases of unusual openangle glaucoma that occurred several months after ICCE and responded promptly to treatment, some remaining hypotonous. All three cases had retinal disease in the fellow eye, in both eyes, or in the involved eye only. Beckerz4 cited a few anecdotal cases that developed high IOP related to retinal tears, and the pressure normalized after the tears were treated by diathermy. The exact mechanism by which IOP rises temporarily in an otherwise perfectly normal eye following cataract extraction is not yet fully understood. However, several theories have been proposed: (1) Trabecular Meshwork Edema. Edema of the trabecular meshwork caused by the surgical trauma itself has been suggested as one possible cause of transient IOP rise following otherwise uncomplicated cataract extraction.‘6’~‘gg*245”71’27’ (2) Angle Ileformation b_ySutures. Mechanical deformation and distortion of the anterior chamber angle 2og,245 has been demonstrated by gonioscopy as a whitish ridge along the inner surface of the cataract incision, obscuring the angle landmarks.‘7g~180, 1gg~27’~272~37g Campbell and Grant5’ demonstrated such angle deformation by sutures, even when the sutures were passed and tightened without making any cataract incision. Transient decrease in facility of aqueous outflow following cataract extraction was demonstrated by Lee and Trotter,“’ and this improved simultaneously with the disappearance of the edema of the inner wound lips. (3) Inflammation. The usual degree of inflammation that occurs after cataract extraction may cause IOP elevation by one or more of several mechanisms. ‘85*‘86.20gWith the breakdown of the bloodaqueous barrier’61,28’*37g and the formation of plasmoid aqueous,‘22Z0” and with the presumed compromise of trabecular function caused by postoperative iritis,lg6 it is plausible that aqueous outflow decreases and subsequently IOP rises. Added to that is the presence of inflammatory cells, which can also block the trabecular spaces, interfering further with outflow.‘0’.‘“‘.3’5 Studies on indomethacin

GLAUCOMAS

IN APHAKIA AND PSEUDOPHAKIA

83

and aspirin reducing IOP rise through their antiinflammatory (antiprostaglandin) action have also been cited.3”’ Regardless of the exact cause(s) of IOP elevation after cataract extraction, it behooves every ophthalmic surgeon to exercise some prophylaxis through the routine use of anti-glaucoma medications temporarily in all cases.‘2”~‘4”~~7’~272~322 Special care must be taken in eyes that already have advanced glaucomatous visual field loss and those prone to anterior ischemic optic neuropathy.‘26~‘33a~27’~‘72~322 Haimann and Phelps’“’ found that timolol given before and immediately after ICCE done without the use of alphachymotrypsin significantly reduced the incidence of postoperative IOP rise. Obstbaum et al*” and Obstbaum”’ noted the same beneficial effect of timolol following ICCE without alphachymotrypsin, whereas Tomoda et al”‘j’ found that timolol had no effect on the acute IOP rise following ECCE and posterior chamber intraocular lens implantation. Ruiz et al?‘” found that pilocarpine gel given at the end of surgery was the most effective, compared to timolol or 4% pilocarpine drops, in minimizing the immediate IOP rise after ECCE and posterior chamber intraocular lens implantation. RichFx’ reported that high doses of intramuscular and oral acetazolamide given during the first 24 hours following ICCE (without alphachymotrypsin) significantly reduced the magnitude of postoperative IOP elevation. Jaffe,‘“’ on the other hand, reported that acetazolamide given intramuscularly was not useful in preventing the postcataract-extraction IOP elevation, regardless of whether it was used with ICCE or ECCE, or with or without intraocular lens implantation. A recent report”““” describes the efficacy of preoperative 1% apraclonidine hydrochloride, an alpha-2 adrenergic agonist, in minimizing postoperative IOP increase following ECCE and posterior chamber IOL implantation. We routinely give a small dose of acetazolamide for two days postoperatively or until the IOP can be measured.

related to total laser energy used, nor to the size of capsulotomy produced.3”4 Richter et al”’ found that most patients who had an IOP rise of 5 mm Hg or more at one hour after laser treatment ended up with a rise of at least 10 mm Hg at four hours, and that IOP elevation tended to be more if the laser energy exceeded 200 millijoules. Moreover, decreased outflow facility was demonstrated up to one week following laser treatment. These authors also observed that pseudophakic eyes were less likely to develop IOPs of 40 mm Hg or higher, and had significantly lower IOP peaks than aphakic eyes, but that glaucoma patients were more prone to develop IOP elevation following laser capsulotomy. Smith”“i also demonstrated a 43% reduction of outflow facility one hour following laser treatment, which improved to 92% of the normal value by one week. The pretreatment C-value was not of any help in predicting the magnitude of IOP rise, nor was there any correlation between the number of laser applications and the postlaser IOP level or C-value. Keates et al17’ found that IOP rose significantly after laser if the pretreatment levels were higher than 20 mm Hg, or if there was preexisting glaucoma. Permanent IOP elevation following laser capsulotomy has been reported,X7,‘g’.“72.“~” sometimes requiring medical therapy and laser trabeculoplasty,“’ and in other instances leading to progressive visual field 10ss.‘!~’ There has been one report of acute glaucoma developing following laser membranotomy in an aphakic eye with previous filtering surgery where vitreous herniated through the laser opening to occlude the filtration fistula.“‘” The FDA report on nd:YAG lasers”“” indicates that 24-547~ (mean 39%) ofpatients had an IOP rise of 5 mm Hg or more, and S-55% (mean 28%) had a rise to levels higher than 30 mm Hg, within two to six hours after treatment. The maximum IOP elevation occurred between 1.5 hours and 4 hours in most cases, 60%1 returning to below 22 mm Hg in 24 hours, and 90% in one week. By three to six months, only 1% had IOPs above 30 mm Hg. The risk factors identified by this report were (1) a preoperative IOP of 20 mm Hg or higher, (2) preexisting glaucoma, (3) high total laser energy used, (4) the use of cycloplegics, and (5) multiple laser sessions. An average of 0.1% of the cases developed pupiilary block glaucoma following laser capsulotomy; these were eyes without surgical iridectomy. Therefore, it is extremely important to give prophylactic antiglaucoma treatment before and after laser capsulotomy in eyes that already have advanced glaucomatous damage, as well as in normal and acetazoeyes. Pilocarpine,‘” timolol ‘1:~:‘.L’.~X,:l:‘i.“l,!’ lamide’“’ have all been tried with variable results.

e. Neodymium: YAG Laser Posterior Capsulotomy Transient IOP elevation, sometimes to dangerous levels,“” is a well recognized complication of neodymium : YAG (nd: YAG) laser posterior capsulotomy. It.Jo.7n.x7,ll~l.lo7.l7l,l73.l~~.z33,~5~,~75,~67,:~:~4, x’5.3tR~“‘i’( This complication is said to occur in up to 95% of’ cases,“) especially those with preexisting g~aucoma,107%‘71.‘4” or those in which the pre-laser IOP is 20 mm Hg or higher.“’ It is also more common in aphakic than pseudophakic eyes,‘8X,“‘3~““4 and in eyes with sulcus-fixated posterior chamber lenses than those with capsular fixation.“6d The magnitude of postlaser IOP rise does not seem to be

“:lY.:I:j4.:~35.:~fi:j

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Surv Ophthalmol

36 (2) September-October

More recently, apraclonidine has also been found to be effective.275 The exact mechanism and pathogenesis of this type of secondary glaucoma is not completely understood,*‘* and detailed discussion of this particular aspect is beyond the scope of this review. 2. Sustained/Permanent IOP Elevation

a. Preexisting Primary Open-angle

Glaucoma

Persistent IOP elevation following cataract extraction, and in the presence of a wide open angle, should always alert the examiner to the possibility of preexisting chronic (primary) open-angle 6,14,63,64,102,110,145,161,185,196,209,271,272.379~~, ap_ glaucoma. pearance of the optic nerve head is very useful in trying to determine the duration of the glaucoma, and so are any visual field abnormalities.

b. Positive Steroid Response If IOP starts rising only a few weeks after surgery, then a positive steroid response has to be kept in mind 63~186~197~209~245~251~271~272~313~376~38l u sually this can be verified rather easily by stopping the steroid treatment or even by similarly provoking the contralateral eye. Intractable glaucoma has also been described with periocular depot steroid injection given at the end of cataract extraction.286 c.

Vitreous in the Anterior Chamber

Intracameral vitreous has frequently been incriminated as a cause of IOP elevation in aphakic eyes. 6,102,110,123,152,154,156,161,185,197,209,217,27l,272,302,323,379,381, 3g7 While vitreous may be regarded as a viscoelasticlike substance, it is difficult to prove its role in obstructing outflow channels. Clinically, it is quite common to see normotensive eyes with their anterior chamber full of vitreous.27’~272~306Experimental studies, though, have shown that vitreous injected into the anterior chamber of eye bank eyes does reduce outflow facility, and that this effect is abolished by hyaluronidase.‘23 Our own clinical impression, and that of others, *Oghas been that vitreous remaining in the anterior chamber after incomplete anterior vitrectomy seems to be more likely to result in secondary glaucoma than does filling of the chamber as a result of spontaneous rupture of an intact hyaloid face months or years after uncomplicated ICCE, or after Nd:YAG posterior capsulotomy. Presumably, the inflammation and its sequelae that accompany vitreous loss contribute to permanent IOP elevation through more than one mechani~m.2’7~2’1~2’2~32”

The management of open-angle glaucoma caused by vitreous consists of the usual antiglaucoma medications, mydriatics, or even vitrecin some cases; spontaneous resolution of tomY302,37g

TOMEY,

1991

TRAVERSO

the glaucoma has also been described with condensation and retraction of the vitreous away from the trabecular meshwork.*“~*‘*

d. Ghost Cell Glaucoma Ghost cell glaucoma in the aphakic eye occurs as a result of chronic vitreous hemorrhage, with subsequent release of ghost cells across a disrupted vitreClinically, there are numerous face. 56,58,5g,61*355~38’ ous khaki-colored ghost cells floating in the anterior chamber and vitreous cavity, with a hypopyon-like sediment in the anterior chamber 6~51~56~58~59~61~100~246~251~271,272 Ghost cells with their typical Heinz bodies can be visualized by phase contrast microscopy of aqueous or vitreous aspirates 56,58,59,61,356 Summers and Lindstrom355 reported six cases of ghost cell glaucoma caused by intraocular lens-induced hemorrhage (iris-fixated or anterior chamber lenses), and seepage of the blood cells into the vitreous cavity. Campbell et a15’jdemonstrated in enucleated human eyes that ghost cells obstructed the outflow channels because of the reduced pliability of these cells, as compared to fresh red blood cells, which mold themselves readily and pass through the trabecular spaces with ease. Vitrectomy is frequently necessary to eliminate the reservoir of ghost cells and achieve adequate IOP contro1.355*38’

e. Irreversible

Trabecular

Meshwork Damage

Any one of the causes mentioned previously may result in ultimate trabecular damage or dysfunction.6,‘g6,25’ Clinically, there may not be any signs of such damage, other than the increased IOP, and the picture would be basically that of an openangle type glaucoma; for example, steroid-induced glaucoma in an otherwise perfectly normal looking aphakic or pseudophakic eye. fi Inflammation Protracted inflammation can develop after cataract surgery, with or without intraocular lens implantation, with sustained IOP elevation and an open angle. lo2 Three such cases were described by Cashwell and Reed.63 Uveitis with glaucoma and hyphema, usually abbreviated as the “UGH syndrome,” used to occur rather frequently in the beginning of the intraocular lens era, especially with the first generations of iris-fixated and anterior chamber lenses. 6,14.73,97,98,170,186,196,251.379,381,401 The UGH syndrome is rare with posterior chamber lenses, but has been reported.14*2’g~264~267 This type of secondary glaucoma is often reversible with removal of the offending implant,6~g7~g8~‘70~‘g6~25’~37g~3s1 unless

GLAUCOMAS

IN APHAKIA

AND PSEUDOPHAKIA

significant damage to the outflow channels occurs as a result of the inflammatory/hemorrhagic process itself, or by direct injury to the angle by the intraocular lens haptics. (See section II. B. 3. d.) g. Late Hemorrhage Intraocular hemorrhage has been described to occur months or years after cataract extraction, either as a result of vascularization of the cataract incision,“” the so-called Swan syndrome,35Y*360~3n6 or because of iris and/or ciliary body chafing or erosion by the intraocular lens.‘67,2’6.‘64*3gfIn such situations, it is conceivable that secondary glaucoma may ensue if the amount of anterior chamber bleeding is significant. Ghost cell glaucoma secondary to intraocular lens-induced vitreous hemorrhage has also been described.“55 B. CLOSED ANGLE I. With PupiIIary

Block

Synechial closure of the angle is said to be the most common cause of glaucoma in aphakia,g4 and pupillary block is the most common cause of angle closure after cataract extraction.“‘.“’ The pupillary aperture can become occluded by any surface that it comes into apposition with, whether this surface is behind the iris or in front of it.6,‘“,20,5”,64.65,66,81.9~.

Fig. 2.

Iris-cornea touch in a case of pseudophakic

pu-

pillary block.

ous complications and difficulties. Hence, it has become our firm conviction that the potential benefits of routine primary surgical iridectomy far outweigh the various risks that are claimed by contemporary cataract surgeons. This view is also shared by others.:WWKl The most important causes of pupillary block in aphakia and pseudophakia are discussed in the following sections.

~O2,~~~:4,~1~!l.~~1~.~611.~6~.?4:~~"4j,24x.271.'?~4.3O3

The presence of a functioning surgical iridectomy is known to prevent pupillary block situations, or at least to reduce their chances of occurring.'6,IOZ.IO3.IIO.I66.'97.443.248. Y7 l.~72.:ll~5,5L'lj.:(SL'.:19B

However, many of the aphakic or pseudophakic eyes that do not have iridectomies never seem to develop pupillary block, while others do even in the presence of an iridec'1".7h.IO9.L'7S.30:~.378.:~XX There is a general tendency tomy: among cataract surgeons today not to do an iridectomy routinely with posterior chamber implants. lIJL'.:~ll4.:~llJ.527 Some of them even advise against an iridectomy on the premise that it constitutes unnecessary trauma to the iris, which could predispose to cystoid macular edema. In recent reports, however, two out of two cases,Rg6 and 11 out of 12”“” that developed pupillary block following ECCE and posterior chamber intraocular lens implantation had not had an iridectomy at the time of surgery. Laser iridotomy is a very useful, noninvasive modality of treatment in cases of pupillary block.“‘. 9NX.‘06 However, in our own experience, laser treatment may not always be easy or effective when performed under acute conditions, namely with severe IOP elevation. Very often, recently operated eyes that present with pupillary block are quite tender and congested, and the iris is practically touching the cornea1 endothelium (Fig. 2). Laser treatment under such circumstances can be fraught with seri-

a. Air Bubble The presence of a gas bubble behind or in front of the iris in an aphakic eye may temporarily interfere with aqueous traffic across the pupil, with subsequent pupillary block and secondary angle-closure Air englaucoma. 2O..54.8l.94,lO3.llO.l59.16O.?O9."7l.27~,:~~l,~~~~,4O~ trapment behind the iris can occur even in the presence of a sector iridectomy.‘“” Luckily, this situation is self-limited in most cases, or easily reversible by proper positioning of the patient and mydriasis. However, if a large volume of an expanding gas is used, as in some retina operations where SF6 or C3F8 gas is used, the pupillary block may not be as easy to remedy. In the aphakic eye that requires extensive retinal reattachment surgery using an expanding intraocular gas, we have frequently been faced with a situation whereby the anterior chamber becomes totally flat as a result of the gas bubble expanding within the vitreous cavity, blocking the pupil, and displacing the iris forward. This situation may persist even after part or all of the gas bubble is absorbed. In such eyes, it seems that the extensive inflammatory process that results from prolonged surgery promotes iridocorneal adhesions, which keeps the iris against the cornea even after the gas-induced pupillary block situation is no longer present. In our own experience, medical treatment is usually completely ineffective in break-

86

Surv Ophthalmol

36 (2) September-October

1991

TOMEY, TRAVER!SO

ing these adhesions; they have to be lysed surgically by anterior chamber deepening with a viscoelastic substance in order to prevent the formation of extensive peripheral anterior synechiae.

b. Vitreous Face Pupillary block by vitreous has been recognized 4,11,44,54,64,65,66.81.82,103,110,145.154,156,160,183. for a long time. 197,228,245,261,268.276.280.306,307~316~323~350~351~352~357~379~391

it

is

said to occur more commonly after round-pupil cataract extraction.65*66*314,323,352 Shaffer stressed the role of posterior vitreous detachment in predisposing to pupillary block by vitreous and to malignant glaucoma in aphakic eyes.“‘j The anterior hyaloid face is known to mold itself quite readily into the pupillary aperture280 as well as through the iridecoccasionally blocking both openings and tomy, causing secondary angle closure. Posner276 described three stages of pupillary block by vitreous, the earliest being a relative block caused by decreased permeability of the hyaloid face. A more severe stage results from adhesions that form between the vitreous and the sphincter pupillae, referred to as “sphincteric pupillary block.” Finally, the “irido-hyaloidal” stage occurs when there are extensive adhesions between the entire posterior iris surface and the anterior hyaloid face. From clinical experience during the ICCE era, pupillary block by vitreous occurs almost invariably in all cases without iridectomy. Hence, there is very little dispute about the preventive value of an iridectomy in the presence of an intact anterior hyaloid face.“““’ Swan stressed the importance of basal iridectomy in preventing forward herniation of the vitreous and late anterior chamber shallowing.357 More recently, pupillary block by vitreous has been described to occur following nd: YAG laser posterior

capsulotomy,76~211,296~303~325~326~349~351

very

much like what used to be described after surgical discission of the posterior capsule.‘54 Therefore, in eyes that do not have a surgical iridectomy, it is highly recommended that a laser iridotomy be made at the time of laser capsulotomy.272~304 An aphakic eye with an intact posterior capsule and no intraocular lens must always have an iridectomy. Not only is this in anticipation of future laser capsulotomy and protrusion of the vitreous face, but because the posterior capsule itself can be the cause of pupillary block, as will be discussed below. Medical treatment of pupillary block by vitreous includes vigorous dilatation and the use of hyperosIn our experience, motic agents. L58.183,197.307*39P.393 this is rarely effective. Laser iridotomy is a very useful, noninvasive modality of treating pupillary block by vitreous

and

by other

causes,

as will be

Fig. 3. Collection of aqueous in the retrocapsular space. (Reprinted from Tomey KF et a1371with permission from the American Journal of Ophthalmology. Copyright by the Ophthalmic Publishing Company, 1987).

discussed later.86,378,3g6 Previously, the xenon arc was reported to be useful in the treatment of aphakit pupillary block following ICCE.261 The classical treatment for pupillary block in aphakia has always been surgical iridectomy.84*306s 307,316.350,351,352,357 Other modalities include anterior vitriotomy,80*306~35’mechanical separation of iridovitreal adhesions with a blunt spatula,‘46s’45 and mechanized removal of the vitreous through the pars plana, either by vitrectomy2’4*268 or by ultrasonic fragmentation.’ I7 c. The Posterior Lens Capsule In the absence of an intraocular lens, and sometimes also in its presence, the posterior capsule may come into firm apposition with the iris, sometimes occluding the pupil as well as the surgical iridectomy. ‘838288,37’ Aqueous accumulates behind the iriscapsule diaphragm, displacing it forward. Clinically, the anterior chamber becomes diffusely shallow and aqueous accumulates in the retrocapsular space, between the posterior capsule and the anterior hyaloid face, also known as the “canal of Petit” (Fig. 3). Biomicroscopically, this manifests as a clear space between the capsule and the anterior hyaloid, the face of which is seen displaced backwards. We recently described nd : YAG laser posterior capsulotomy as an alternative to laser iridotomy for the relief of selected cases of pupillary block in aphakic and pseudophakic eyes 371(Fig. 4). When there is no intraocular lens, then capsulotomy done anywhere will relieve this type of block immediately. However, with an intraocular lens in place, the capsulotomy has to be placed either outside the edge of the optic or through one of the positioning holes of the intraocular lens; otherwise, the optic itselfwill block

GLAUCOMAS IN APHAKIA AND PSEUDOPHAKIA

Fig. 4. Left: Pupillary block by the posterior capsule. Right: Deepening of the anterior chamber of the same eye immediately after nd: YAG laser capsulotomy. (Reprinted from Tomey KF3” with permission from the AnwricanJournal of Ophthalmology Copyright by the Ophthalmic Publishing Company, 1987).

the capsular opening, thus preventing the aqueous from gaining access to the anterior chamber from the retrocapsular space.“88 We like to refer to this phenomenon of retrocapsular accumulation of aqueous as anterior aqueous misdirection, or posterior pupillary block.“” The role of the posterior capsule as a barrier between the posterior and anterior chambers has also been emphasized by Lynch et ap”’ in their report about the management of pseudophakic malignant glaucoma by pars plana vitrectomy combined with localized capsulectomy.

d. Intraocular Lens Pupillary block by the intraocular lens surface has been described for iris-supported lenses, and anterior as well as posterior chamber lenses.6*‘4.45,54,63.76, R6,105,109.174.175.181.186.196,197.243.248.251.259.303,343,326.378,379.38l,388, 392,:(96 fan

Buskirk

found even more pupillary block in pseudophakic eyes with anterior chamber lenses than in aphakic eyes. The absence of a functioning surgical iridectomy is known to predispose to pseudophakic pupillary block,“““, s88*3g6 especially with anterior chamber lenses, where it is advisable to perform at least two iridectomies at the time of Weinreb et surgery. 102~105~175~181~196~243~2~~l~319~326~37R~381.401 al”‘” reported six patients, all diabetics, who developed pupillary block after ECCE and posterior chamber intraocular lens implantation without surgical iridectomy. They suggested that diabetics could be predisposed to such a complication, presumably because of the increased thickness of the iris and ciliary body in diabetics, and probably also because of their tendency to develop postoperative inflammation. e. Seclusio Pupillae Total posterior

synechiae

all along the pupillary

margin as a result of severe inflammation is a well known and obvious cause for pupillary block in aphakic or pseudophakic eyes whenever there is excessive postoperative inflammation.54.“4.‘n2.’ “‘.“‘,. 16O.in3.245.271.272,35?.5n3 Laser

iridotomy

is

usually

cura_

tive in the early stages; however, bleeding at the iridotomy site occurs frequently, and the laser opening may become obliterated by an inflammatory membrane of fibrovascular tissue. Sometimes a surgical iridectomy may be required. Intraocular pressure elevation can persist despite an iridectomy, if a significant part of the anterior chamber angle is involved by peripheral anterior synechiae, because of either the inflammatory process itself or of prolonged flattening of the anterior chamber.“’ j:

Silicone Oil

Pupillary block has also been described in aphakit eyes undergoing retinal reattachment surgery with intraocular silicone oil injection.” An inferior iridectomy is recommended in these cases to prevent such a complication. The inferior location of the iridectomy is important to allow the free passage of aqueous while the lighter oil floats on top. 2. Aqueous Misdirection Classically referred to as malignant, or ciliary block’“4~‘X7*“g’glaucoma, this entity is a rare complication of cataract extraction, with or without intra6.l4.l02.l:~l.ltiO,lH7.“10.“71.?72,:~l~ It ocular lens implantation. sometimes occurs bilaterally.““” The diagnosis of aqueous misdirection has always been a source of confusion to many ophthalmologists, particularly in differentiating it from pupillary block. Following ICCE, it may be especially difftcult to make such a distinction. With pupillary

Surv Ophthalmol

36 (2) September-October

1991

TOMEY, TRAVERSO

Classical aqueous misdirection (malignant glaucoma) with aqueous accumulating within the vitreous

Fig. 6.

Aqueous misdirection caused by a loose running suture following cataract surgery.

Fig. 5.

body. (Reprinted from Tomey KF et a13” with permission from the American Journal of Ophthalmology. Copyright by

the Ophthalmic Publishing Company, 1987).

block, however, the central anterior chamber is described to be deep, but with marked peripheral shallowing due to prominent forward bowing of the iris (iris bombe). 323We recently sugg ested a simplified classification of these various entities.372 We like to regard this group of aqueous flow abnormalities as one spectrum, with classical pupillary block at one end and true iridovitreal aqueous misdirection on the other. Retrocapsular accumulation of aqueous, as described earlier, represents an “intermediate variant” of aqueous misdirection. Among the factors that predispose to aqueous misdirection are the following: (a) Small-sized globe, an extreme example being nanophthalmos. 3g1A recent report described a case of malignant glaucoma that was attributed to an over-sized posterior chamber intraocular lens (7 mm optic) implanted in a small globe.“’ (b) Postoperative leakage from the surgical incision. This can be accidental or “deliberate,” as in the case of simultaneous filtering surgery. We have thus always discouraged the practice of loose suturing of cataract incisions, especially when a running-suture type of closure is used. Such practice among the astigmatism-conscious surgeons has often led to inadvertent leakage, with the subsequent vicious cycle of anterior chamber shallowing and aqueous misdirection (Fig. 5). (c) The absence of a functioning surgical iridectomy, predisposing to pupillary block, which in itself may be one of the initial phases in the spectrum of aqueous misdirection as mentioned earlier. (d) A combination of the above factors. Aqueous misdirection is not always easy to diagnose. Typically, there is diffuse shallowing of the anterior chamber with high IOP (except in the presence of a simultaneous filter or leak) in the

presence of a functioning iridectomy. If there is no clinically visible collection of aqueous in the retrocapsular space (which we called anterior aqueous misdirection), it is then presumed that aqueous is accumulated behind or within the vitreous body,lE7 either diffusely or in the form of discrete lacunae, ‘46,3’6which can sometimes be outlined by ultrasonography.53 This is the classical form of posterior aqueous misdirection or malignant glaucoma (Fig. 6). A shallow or flat anterior chamber in the presence of an intraocular lens poses an urgent situation because of the pseudophakos-induced endothelial damage in case there is actual touch between the endothelium and the intraocular lens. Hence, immediate intervention is usually a must. Medical treatment of aqueous misdirection, consisting of vigorous cycloplegia and hyperosmotic agents, is frequently ineffective, 3z6S370Other options include deep incision and aspiration of the vitreous with anterior chamber ~~~p~~~~g,'~,67,68,'02,'60,'8~.l~~,22~,~~6. 32g,3g1anterior

vitrectomy,1s7~3’7~353pars plana vitrectomy ‘87~2’o~370 with or without intraocular lens removal, shrinkage of the ciliary process by transpupillary argon laser photocoagulation,1”7~~0’*32g~3s7 or - in desperate, terminal cases - cyclodestruction, either by cryotherapy or by transscleral nd: YAG laser cyclocoagulation. Neodymium : YAG laser vitreolysis has been reported to successfully reverse aqueous misdirection situations in some pseudophakic

eyes.46.99,102,248,329

In cases where pupillary block cannot be ruled out, the response of the eye to laser iridotomy or capsulotomy may help establish the diagnosis one way or the other, or even be curative if the situation turns out to be strictly pupillary block. In a pseudophakic eye with aqueous misdirec-

GLAUCOMAS

IN APHAKIA

AND PSEUDOPHAKIA

tion, removal of the intraocular lens often carries high morbidity,‘g7.320 and is usually not helpful in reversing the situation unless combined with generous vitrectomy. Even then, IOP may remain elevated because of permanent trabecular damage. In general, intraocular lens removal, whether in cases of aqueous misdirection or in any other type of secondary glaucoma in pseudophakia, is seldom indicated or helpful in achieving better IOP control. ‘75.37gWe have managed cases of pseudophakic aqueous misdirection successfully by pars plana vitrectomy without having to remove the intraocular lens.370 Lynch et a12” described pars plana vitrectomy in four cases of pseudophakic malignant glaucoma where medical and laser treatment had failed. They recommended localized capsulotomy and zonulectomy with the vitrectomy instrument to re-establish communication between the posterior and anterior chambers. 3. Without Pupillary Block The anterior chamber angle may become permanently and irreversibly damaged by peripheral anterior synechiae via mechanisms other than pupillary block. ‘K’~’ Silent peripheral anterior synechiae have been reported to occur in 47% of otherwise uncomplicated cataract extractions.“”

a. InflammationlHyphema Severe postoperative inflammation may lead to progressive angle closure by peripheral anterior 6.4O,64.66,94.llO.l45.l6l.l97,2~l.323 By the same arsynechiae. gument, massive anterior chamber bleeding may result in permanent angle damage because of the associated inflammation and eventual synechiae 94,'X5,'9R.?7',272,379 formation. Rubeosis iridis from any cause ultimately results in permanent angle closure unless it is arrested by treatment of the underlying ischemic process. Such a mechanism of angle closure, like other inflammatory conditions, is not peculiar to aphakic eyes, although it is known that cataract surgery does accelerate new-vessel formation in predisposed eyes.“H4 h. Probonged Anterior Chamber Shallowing Postoperative wound leaks or other causes, like pupillary block or ciliochoroidal detachment, that leave the peripheral anterior chamber flat for five days or longer eventually result in permanent damage to the outflow system due to the formation of peripheral Jo6~~‘L’s~sx’~

anterior

Cotlie?”

synechiae.40~64~66~83,94~‘02~24~~27’~~’~~

found

that secondary

glaucoma

due to loss of the anterior chamber did not develop if surgical repair was carried out within five to six days. Others recommend reformation or chamber within 24 hours.‘“2

of the anteri-

Fig. 7. Tip of a Molten0 implant (arrow) positioned behind the iris in an aphakic eye with total obliteration of the anterior chamber after penetrating keratoplasty.

Shingleton et alsZ4 recently suggested that peripheral anterior synechiae caused by aphakic or pseudophakic pupillary block (among other causes of angle closure) can be released using goniosynechialysis, a technique originally advocated by Campbell and Vela.” The angle closure, however, has to be less than six months old. Moreover, more than half of the aphakic and pseudophakic eyes treated required additional glaucoma surgery, like cyclodialysis, as well as some antiglaucoma medical treatment. c. Iris Incarceration

in the Surgical Incision

This may be the result of poor surgical technique and inadequate closure or postoperative dehis40,64,6fiX I.94.'K!,:~X I If left untreatcence of the incision. ed, many of these cases may develop progressive angle closure, depending on the severity of iris trauma and the amount of postoperative inflammation. With gross peripheral anterior synechiae and/or fibrovascular tissue in the angle, any form of fistulizing operation becomes technically difficult and unrewarding. Although the chances of success of filtration in such aphakic eyes in general have been somewhat improved with the use of 5-fluormany of‘ these cases in ouracil (5_FU),‘“‘.‘44.2g8.3”.5.9XS our experience still fail and end up requiring an artificial drainage implant. Even then the success rate is not very encouraging. This situation is encountered frequently in aphakic eyes that require repeated cornea1 transplants, with repeated manipulation and excision of the iris, which ultimately leaves a small stump of iris that adheres to the suture line and totally obliterates the peripheral anterior chamber and angle. We have had to introduce the tubes of artificial drainage implants through the iris (Fig. 7).

90

Surv Ophthalmol

36 (2) September-October

TOMEY,

1991

TRAVERSO

d. Intraocular Lens Haptics Anterior chamber intraocular lenses have been shown to cause progressive synechiae in the anterior chamber angle, ultimately resulting in secondary angle-closure glaucoma. 6,14.45.152,175.197.2?4,251.265.274.294. 2g5.37g Poleski and Willis’75 demonstrated peripheral anterior synechiae around anterior chamber intraocular lens haptics in 18 eyes with normal IOP. In analyzing anterior segment complications of intraocular lenses, Polack273 found more secondary glaucoma with anterior chamber lenses. Pearce”‘j5 reported peripheral anterior synechiae in 30% of eyes implanted with the earlier designs of the Choyce style lenses, namely Marks V, VII, and VIII. Damage to the angle has been demonstrated by histopathologic studies.45,‘“4 13resnick45 described secondary glaucoma in 10 out of 17 eyes that were enucleated after complicated cataract extraction and anterior chamber intraocular lens implantation, using the Choyce, Ridley, or Strampelli styles. Four of these eyes were also found to have epithelial downgrowth. Van Buskirk37g stressed angle damage that could result from malpositioning or improper size of an intraocular lens. He emphasized the fact that peripheral anterior synechiae can result from a mobile, undersized anterior chamber lens, an oversized lens that erodes through the angle, or any other type of lens that causes chronic inflammation because of poor positioning. In general, an anterior chamber intraocular lens is contraindicated in an eye with preexisting peripheral anterior synechiae.2g5 Anterior chamber lenses with closed loops are especially prone to induce progressive angle closure and should be avoided. 274 Recent reports ‘04,37g,380have also de_ scribed peripheral anterior synechiae caused by the loops of posterior chamber intraocular lenses. Once damage to the angle structures takes place, removal of the intraocular lens, in our own opinion, does not necessarily help improve IOP control. It is quite feasible, in our experience, to perform glaucoma surgery, even seton implantation (Fig. 8), in the presence of the intraocular lens. Therefore, removal of an anterior chamber intraocular lens may not be indicated from a glaucoma standpoint, unless one is dealing with an UGH syndrome, or unless there are other complications, like cornea1 decompensation, a loose-fitting lens, etc. On the contrary, removal of an intraocular lens can be quite traumatic, resulting in the formation of more peripheral anterior synechiae, among other complications.

e. Be-Existing Angle Closure The process of angle closure by any mechanism

Fig. 8. Molten0 implant (arrow) in an eye with secondary glaucoma and an anterior chamber intraocular lens.

may precede cataract formation and surgery;63,“n. 1g6*271~272~37g therefore, the occurrence of angle-closure glaucoma following cataract extraction may be totally unrelated to the operation itself. The importance of routine preoperative gonioscopy cannot be overemphasized; this also helps the surgeon determine whether an anterior chamber intraocular lens can be implanted safely in case of intraoperative difficulties, like vitreous loss, for example. f.

Neovascular Glaucoma

The anterior chamber angle may become closed by a fibrovascular membrane, either before or after cataract extraction.271~272~37g Angle closure can occur either as a result of direct involvement of the angle by the neovascular process, or through a process of pupillary block caused by total obliteration of the pupil by the fibrovascular tissue.271,272 Neovascular glaucoma is generally easy to diagnose, and may be the result of either coexisting diabetic disease or other causes of ocular ischemia, like central retinal vein occlusion or carotid occlusive disease.‘j3 Cataract extraction, ICCE much more than ECCE, is known to accelerate anterior segment neovascularization in eyes with proliferative diabetic retinopathy,384 but neovascular glaucoma has been reported to occur, rarely, even after uncomplicated ECCE with posterior chamber intraocular lens implantation.‘” Weinreb et a1388a described three cases of neovascular glaucoma occurring after laser posterior capsulotomy, which suggests that the posterior capsule plays a role as a barrier against the development of neovascular glaucoma. The management of neovascular glaucoma in aphakia should address first the primary cause of ischemia, like panretinal ablation in diabetics or the ischemic type of central retinal vein occlusion, and treatment of carotid occlusion, if possible.5.‘42,144*

GLAUCOMAS

IN APHAKIA AND PSEUDOPHAKIA

91

Fig. 9. Left: ‘Typical advancing front (arrows) of epithelial downgrowth on the cornea1 endothelium. Right: Edge of epithelial downgrowth (arrows) over iris as outlined by argon laser photocoagulation, causing blanching of the treated epithelium.

97~~~~iH’ For IOP control, medical treatment should be relied upon as much as possible, since glaucoma surgery in neovascular glaucoma in general and in aphakic eyes with neovascular glaucoma in particular is both unrewarding and fraught with complications. Conventional filtering procedures are extremely unlikely to succeed unless combined with 5-FU injections, and even then the success rate in our experience and in the experience of othersZg” is not very high, although some reports are favorprocedures are also able. ‘xL”‘.“‘~ Cyclodestructive especially unpredictable in eyes with neovascular glaucoma, and the risk of phthisis bulbi is higher than in other conditions, as will be discussed later in this paper.:(I :i:(.(i"

twice as frequently after ICCE (30%) as after ECCE (19%). Theobald et al”“” found 0.11% incidence of epithelial downgrowth in reviewing 8062 cases of cataract extraction. Eldrup-Jorgensen”” reported anterior chamber epithelialization in 8% of eyes whereas enucleated after cataract extraction, in 100 enuSchulze et al”” noted a 17% incidence cleated eyes. Maumenee et al,“” based on a review of earlier reports, indicated that epithelial downgrowth was encountered in 16VGof eyes enucleated after cataract extraction. Merenmies et alZYYfound that epithelial downgrowth with absolute glaucoma was the most common cause for enucleation of 85 eyes removed after cataract extraction. Payne et al,“” on the other hand, found that epithelial downWe have had reasonably good success rates with growth was the second most common cause for enuthe single-plate Molten0 implant in eyes with neocleation after cataract extraction (60 out of 333 vascular glaucoma, some of which were also aphaeyes), the first being uveitis with secondary glaucokit.’ Currently, we tend to use the double-plate imma (151 out of 333 eyes). In another review of plants or the long Krupin-Denver valve whenevel 26,47 1 cataract extractions, Bernardino and copossible, and have had good results so far. workers”” described 24 cases of histologically provEven with adequate IOP control, we have found en epithelial downgrowth, 50% of which had glauthat eyes with neovascular glaucoma, whether phacoma. Glaucoma in epithelial downgrowth is kit or aphakic, may continue to lose vision because thought to result from peripheral anterior synechi,,e,“~.‘K:~ pupillary of progression of their basic ischemic disease, espeblock caused by the epithelial cially if the underlying cause of ischemia is not treatmembrane itself,‘“‘.‘8” direct obstruction of the outed.“,‘??,’ i-,.379.:i84 flow channels by epithelial cells, ‘Xi.“R4or necrosis of the trabecular meshwork.‘“’ Iwamoto et al” found Epithelial Downgrowth g. that the electron microscopic features of epithelial downgrowth tissue obtained from specimens of Today this is a rare complication of cataract exposterior keratectomy, iridectomy, and vitrectomy, traction that results from poor closure of the cataract incision ~i..iS.9~~9fi.ll)'?.10R.Il0~lR?~l89~IY7~L'L'l~~~~~~~~~~7l~ were very similar to those of conjunctival (rather 27",:~OO,f I I JL':4.:154.:lfiB.:171).jX9,404 than corneal) epithelium. especially with cornea1 secThe diagnosis of epithelial downgrowth is usually tions. I*‘, It has also been described following surginot difficult to arrive at, with the typical advancing cal discission of a secondary membrane.‘04 front of epithelium seen on the cornea1 endotheliOne of the earliest extensive reports on the suburn and on the iris, and in one report, on the surface ject was written by Calhoun in 1949.“” Blodi”’ reof an anterior chamber intraocular lens.““” Typical ported that epithelial downgrowth occurred almost

92

Surv Ophthalmol

36 (2) September-October

blanching of the epithelium can be elicited by argon laser treatment of the iris in areas that are suspected to be involved by epithelium185~220~346~~47 (Fig. 9). The ultimate fate of untreated eyes is devastating, mainly because of intractable glaucoma and cornea1 Treatment of epithelial downdecompensation. growth is largely unsuccessful and complications are frequent. 220*221Complex surgical procedures have been described for managing such cases.47748V 108,113,165,193,208,220,221,347.354 b ong these procedures 183,185,220,221,245,346,347 application of are cryotherapy, alcohol, and curettage of the cornea1 endothelium.185~220~22’~245~354 Radiation therapy was reported to be effective in the treatment of epithelial cysts, but not of diffuse downgrowth.g’ Beta irradiation is said to be effective when the epithelial invasion involves only the posterior cornea1 surface, but not with deeper involvement.403 Xenon arc photocoagulation of epithelial cysts has also been used.254 Harbin and Maumenee13* reported six cases of intraocular epithelial cysts following cataract surgery, emphasizing that the cell type is similar to that of epithelial downgrowth, and that cysts do not need to be excised, as many stay dormant for a long time. All of these six cases converted to diffuse epithelial downgrowth following surgical excision. Stark346,347reported good results with closed system excision of intraocular tissues involved with epithelial downgrowth, using vitrectomy instrumentation, coupled with cryotherapy to destroy the epithelial tissue. A recent report describes the use of the Molten0 implant for treating secondary glaucoma in cases of epithelial downgrowth.’

h. Fibrous Ingrowth A rare complication of cataract surgery, fibrous ingrowth is usually caused by poor approximation of the cataract incision and/or incarceration of intraocular tissues, like iris, vitreous, or lens remnants within the incision.2*36,g4,163*323,358,37g Glaucoma results from direct involvement of the anterior chamber angle by the ingrowing sheets of fibrous tissue. Treatment of this type of glaucoma is extremely unrewarding. Operations like cyclodialysis and cyclodestructive procedures have been advocated.“j3 Another rare entity that has been reported to be a cause of secondary glaucoma after cataract extraction is cornea1 stromal overgrowth.“* Microscopic examination of these eyes reveals synechial closure of the angle. i. Endothelial

Proliferation

In this very rare condition the cornea1 endotheliurn undergoes libroblastic or myoblastic transformation, obliterating the angle structures and producing peripheral anterior synechiae.222*2g5,338An

TOMEY,

1991

TRAYERSO

Fig. 10. Prominent iris bombe in an aphakic eye with seclusio-pupillae following severe inflammation.

excellent review of epithelial, fibrous, and endothelial proliferation was recently published by Smith et a1.338

Proliferation of Iris Melanocytes Across the Trabecular Meshwork

j.

There is an isolated report of what may be considered a rare form of angle-closure without pupillary block.377

III. Diagnostic Clues A. ANTERIOR

CHAMBER

DEPTH

The depth of the anterior chamber in an aphakic eye with secondary glaucoma is an important clue in establishing the mechanism of IOP eleva110,175 tion. A well formed anterior chamber with aphakic dimensions usually indicates the absence of aqueous circulation abnormalities, like pupillary block or aqueous misdirection. Additional information is gained by the presence or absence of anterior chamber reaction, blood or debris, and especially by gonioscopy, as will be discussed later. A discrepancy between the central and peripheral anterior chamber depth (the former being deeper) usually denotes the presence of pupillary block, especially when there are posterior synechiae and/ or iris bornbe’j4s’j6 ( Fi g. 10). Biomicroscopically, the distinction between pupillary block and aqueous misdirection (malignant glaucoma) is virtually impossible following ICCE. When diffuse shallowing is present, the underlying cause can be pupillary block, especially in the absence of a functioning iridectomy. However, diffuse, uniform anterior chamber shallowing, and, more so, total flattening, usually suggests aqueous misdirection, whether this is the classical posterior variety (malignant glaucoma) or the more recently described anterior or retrocapsular one.488*371,372 As

GLAUCOMAS

IN APHAKIA AND PSEUDOPHAKIA

Clinical conditions and factors predisposing to anterior chamber shallowing. Dotted arrows depict presumed mechanisms; solid arrows indicate more established causal relationships.

Fig. 11.

IRIS-INCISION

I

ADHESION

1

\ ANT. CHAMBER SHALLOWING

-

PUPIL

-

BLOCK cl

mentioned earlier, with vitreous directly blocking the pupillary aperture, as in ICCE, it is impossible to distinguish clinically between pupillary block and aqueous misdirection. The differential diagnosis of shallow anterior chamber after cataract extraction is diagrammed in Fig. 11. B. ANTERIOR

CHAMBER

REACTION

The presence of inflammatory cells, red blood cells, ghost cells, or free particles of lens cortex, or a combination, in the anterior chamber may be partially or totally responsible for IOP elevation. Such a mechanism of secondary open-angle glaucoma in aphakia and pseudophakia has to be kept in mind. C. GONIOSCOPIC

FINDINGS

The appearance of the anterior chamber angle is very important in disclosing the mechanism of glaucoma in the aphakic/pseudophakic eye, just as it is Forward conin the phakic eye. I10.179.19ti.l97.‘L71.?72.379 vexity of the iris periphery (iris bombe) usually denotes an ongoing, active process like pupillary block. In extreme cases where the peripheral anterior chamber is almost flat, angle closure is obvious on mere slit-lamp examination, and gonioscopy does not provide any additional information. Synechial closure of the angle speaks for the chronicity of the glaucomatous process, and may also suggest the possibility of preexisting angle closure. It has been suggested that peripheral anterior synechiae in aphakic eyes may be anterior to (and thus only obscuring) normal trabecular meshwork,

which explains the favorable response to strong miotics.fig However, this observation was not supported by Hitchings,14’ who also described peripheral anterior synechiae in 23 out of 41 normal eyes after round-pupil cataract extraction, and observed that IOP rose above 31 mm Hg whenever these synechiae involved more than 100 degrees of the angle circumference. Angle closure due to iris neovascularization is detected readily. The anterior chamber here remains deep, unless there is a concomitant process of pupillary block secondary to the neovascular membrane itself, In the presence of a wide open angle with normal landmarks, other mechanisms of glaucoma have to be considered, like preexisting primary open-angle glaucoma, a positive steroid response, etc. An open angle also provides an additional therapeutic option, namely argon laser trabeculoplasty. D. DISC APPEARANCE FINDINGS

AND OTHER

FUNDUS

Fundus abnormalities can offer valuable diagnosticcl ues. 11~1.17A~I97 Advanced glaucomatous disc damage reflects longstanding disease, possibly indicating a preexisting glaucomatous process. Evidence of vascular abnormalities, like what is seen in diabetes mellitus or central retinal vein occlusion, may shed some light on the etiology of neovascularization. Choroidal detachment should be looked for carefully, by ophthalmoscopy or by ultrasound, in all cases ofanterior chamber shallowing and/or unexplained hypotony.

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E. IRIDECTOMY The presence or absence of a surgical iridectomy ’ ‘J’~ A shallow or flat anteriinfluences the diagnoses. or chamber in the absence of a functioning iridectomy is highly suggestive of a pupillary block situation. Sometimes, the iridectomy cannot be seen by direct slit-lamp examination, but becomes apparent by retroillumination or on gonioscopy. Not every visible iridectomy, however, is necessarily functioning. In some cases, careful examination reveals that the iridectomy is obstructed by the vitreous face, intraocular lens, or posterior capsule.288~371~372 F. POSTERIOR

SYNECHIAE

Adhesions can form between the pupillary margin and any surface that is behind the iris, such as the anterior hyaloid face, the intraocular lens surface, or the posterior capsule. An obvious consequence of such adhesions is pupillary block, especially in the absence of a functioning iridectomy. G. FILTERING

BLEB

The presence of a functioning filtering bleb may sometimes explain the paradoxical situation of pupillary block or aqueous misdirection with normal or even low IOP. This situation is seen frequently following the glaucoma triple procedure (trabeculectomy combined with ECCE and posterior chamber intraocular lens implantation). In the immediate postoperative period, shallowing of the anterior chamber with hypotony is usually due to overliltration and/or choroidal detachment, but these conditions are eventually self-limited. However, whenever anterior chamber shallowing recurs at a later date, the possibility of “normotensive” pupillary block or aqueous misdirection should be kept in mind.307 Pupillary block with normal or low IOP can also be seen in the presence of a wound leak and/or choroidal detachment.323 H. WOUND DEHISCENCE Poor approximation of the surgical incision or postoperative dehiscence may start a vicious cycle of forward displacement of the iris-pseudophakos (or iris-capsule) diaphragm and aqueous misdirectionlg6 (Fig. 5). Alternatively, prolapse of the iris through the gaping incision may trigger progressive peripheral anterior synechiae formation and, eventually, intractable secondary angle-closure glaucoma. lg6Poor approximation of the surgical incision may also invite epithelial downgrowth or fibrous ingrowth. I. ULTRASOUND

EXAMINATION

Echographic evaluation of the posterior pole is frequently helpful in the differential diagnosis of

Fig. 12. Hemorrhagic and serous choroidal detachment seen on B-scan in an aphakic eye with a flat anterior chamber

following

filtering

surgery.

postoperative shallow or flat anterior chamber. Choroidal detachment can be detected easily in cases where direct visualization is difficult for some reason (Fig. 12). In cases ofaqueous misdirection, it may be possible to demonstrate the intravitreal accumulation of aqueous lacunae using special echographic techniques.53 J. LASER IRIDOTOMY As mentioned earlier, the distinction between pupillary block and aqueous misdirection may be quite difftcult to make on clinical grounds. The former condition is suspected more in the absence of a functioning iridectomy. Hence laser iridotomy can be resorted to, not only for treatment (and sometimes even cure) of pupillary block, but also as a diagnostic test. In general, pure pupillary block situations, but not aqueous misdirection, are relieved promptly by iridotomy.‘1*‘s3 In cases where the anterior chamber is extremely shallow and the iris is practically touching the cornea, it is difficult to achieve an iridotomy by laser without seriously injuring the cornea1 endotheliurn. In such a situation, we have introduced nd: YAG laser posterior capsulotomy as an easier and equally effective alternative to iridotomy.37’ In the presence of a posterior chamber intraocular lens, the capsulotomy has to be positioned either outside the boundary of the lens optic or through one (or more) of the positioning holes.*”

IV. Treatment A. MEDICAL TREATMENT Intensive, longterm medical treatment of the glaucomas in aphakia and pseudophakia is generally encouraged and preferred,342~343 because the surgical options in these eyes are usually less successful

AND PSEUDOPHAKIA

95

and carry greater morbidity than in phakic eyes.“” With aphakia it becomes possible to use strong miotics 110~?45.?71.?7?~~H6.313 but preferably not epineph-

This approach is feasible only if there is a large sector iridectomy or iris coloboma which allows visualization and treatment of a sufficient number of ciliary processes.29” More recently, endophotocoagulation of the ciliary processes has been described.““” This, however, requires good experience with advanced, modern vitreous surgical techniques. It is probably a practical option if performed as part of other procedures, like pars plana lensectomy/vitrectomy in an eye that also needs surgical intervention for intractable glaucoma. On the other hand, endocyclophotocoagulation as an isolated primary procedure is difficult to justify, in our opinion, because of its potentially high morbidity, especially since the longterm results are still not known.

GLAUCOMAS

IN APHAKIA

f

risk of retinal rine compounds. IO?,I82.245,271,272 The detachment has to be borne in mind with the for,10.175.197.L'7, .-"71.31:~and the risk of cystoid macular mer edema with the latter IO?~I45.15?,175,lX2,197~2O9~2l~~~2~~l.?7l~ 272.2t(4.:~I:I.:I":i.:16X.379

Cystoid macular edema is said to occur in up to 30% of aphakic eyes that receive epinephrine treatment,‘s’.“0g perhaps more commonly after ICCE than ECCE.272.“‘” Periodic followup with fluorescein angiography has been recommended for aphakic patients on epinephrine.“” Whether dipivefrin carries the same risk as epinephrine has not been established.“‘.“‘” The longterm use of carbonic anhydrase inhibitors may be justified in some cases where surgical treatment is technically difficult or hazardous.‘g7 Some cases of pupillary block may benefit from intensive cycloplegia

and

mydriasis.“~,““,G”

In some types of glaucoma in aphakia, and in the immediate postoperative period in general, there may be an element ofinflammation, which warrants anti-inflammatory treatment together with the antiglaucoma treatment,‘“7.L)X’.379 except for miotics, which should be avoided in such cases.‘75~1g7.95’.‘7L’ In our experience, and in the experience of others,“” epinephrine compounds may be irritating in inflamed eyes and are better avoided.

B. LASER TREATMENT 1. Argon Laser

The argon laser has been used successfully to relieve situations of aphakic and pseudophakic pupillary block, by both iridotomy and photomydriasis. xti,lxl.?4x.?~l.252.:~67,~~7~ Also aphakic and pseudophakic eyes with normal angle landmarks may benefit from argon laser trabeculoplasty,““’ although to a lesser extent than in phakic 7“ 127.I39,li".27L',379397.:19x especially with vitreous eyes;-filling the anterior chamber.“Y’ Robin et al,‘“” on the other hand, reported significant IOP lowering with argon laser trabeculoplasty in aphakic eyes, some of which had even undergone filtering surgery. Pseudophakic eyes are said to respond relatively better to argon laser trabeculoplasty than aphakic eyes.‘7” As mentioned earlier, the argon laser can also be useful for photomydriasis to break iris-intraocular lens adhesions and relieve pupillary block.“‘.““‘.‘” Transpupillary coagulation of the ciliary processes by laser has been advocated either as a cyclodestructive procedure or for the purpose of shrinking the ciliary processes with the aim of relieving aqueous misdirection (malignant glaucoma) situations in both phakic’“‘,‘“” and aphakic’0’s’“0,‘H7 eyes.

2. Neodymium

: YAG Laser

The nd: YAG laser is particularly useful for iridotomy in pupillary block situations, and also for capsulotomy for the same purpose.““.“” In its freerunning mode, the nd: YAG laser is also being used for transscleral cyclocoagulation, HJ.XY.lW:375.:194a tech_ nique which had also been described using the ruby laser.“” In 1973, Beckman and Sugar?” reported that cyclophotocoagulation using the nd : YAG laser was more effective than with the ruby laser, without any serious complications, even in dark brown eyes. A previous report”’ had indicated that more complications were encountered in darkly pigmented (rabbit and human) eyes when the ruby laser was used for transscleral cyclophotocoagulation. In 1984, Beckman et al” presented their longterm results in 300 eyes treated by cyclophotocoagulation using the ruby laser, the nd: glass laser,. or the nd: YAG laser, with 88% success (IOP < 22 mm Hg and >5 mm Hg) in aphakic eyes with open-angle glaucoma, compared to 62% success in neovascular glaucoma. Hampton et al”” recently reported better success of transscleral nd : YAG laser cyclocoagulation in pseudophakic eyes than in aphakia or in cases of neovascular glaucoma. Favorable prognostic factors seemed to be older age and lower initial IOP. Recent modifications of transscleral cyclodestruction involve the delivery of free-running laser energy via a fiberoptic probe placed directly in contact with the conjunctiva over the ciliary body area.“‘l’ Aqueous misdirection in aphakic and pseudophakic eyes has been reversed successfully in some cases by nd : YAG vitreolysis.““,““,‘~7” Finally, it is possible to use the nd: YAG laser for opening of failed filters in phakic as well as in aphakit eyes. In our own experience, this type of treatment may be effective only in the early postoperative period before extensive scarring of the

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filtering bleb occurs, and is especially helpful in relieving obstructions caused by iris tissue.

C. SURGICAL 1. Surgical

TREATMENT

Iridectomy

Iridectomy to relieve pupillary block has been practiced for a long time, one of the earliest accounts being Bowman’s 1865 description of iris has puncture.44 Since then, surgical iridectomy been recognized as the classical treatment of pupillary block. 102.154.197,209 However, laser iridotomy is becoming more and more the procedure of choice. In our opinion, there are very few indications at this day and age for surgical iridectomy when laser facilities are available. 2. Filtering

Procedures

Any of the filtering procedures that are normally performed on phakic eyes can also be done in aphakia,‘02 although with a lower success rate. 127,136,139.143,152.245,271,272,315 Although performing filtering operations in previously operated, scarred quadrants does not seem to influence the chances of success, according to a recent report,365 many glaucoma surgeons still prefer to avoid these quadrants, anticipating difficulties in dissection of the conjunctival and scleral flaps. Thus, changing from the usual superior location to other nonconventional quadrants, like the temporal or inferior, has been suggested as a possible cause for the low success rate of filtering operations in aphakia, though without any definite evidence.29’ a. Full-thickness

Operations

The classical Scheie procedure or its modifications have stood the test of time and are still preferred by many surgeons over other procedures. Studies in phakic eyes have shown that on the average, the same92s204 or lower17~42J41.339.340.341~3~5 lops, but

higher

complicationsI7~42~92~32I~339~34O~34I.385

are

achieved by Scheie-type operations than by partialthickness procedures. However, no such comparison has been made in aphakia. Rockwood et a12” found no difference in success rate between fulland partial-thickness procedures in a group of eyes, including aphakic eyes, that underwent filtering surgery with 5-FU injection. Also, preliminary observations by Heuer et a1’42 suggest that there is no difference in success rates between trabeculectomy and full-thickness filtration with 5-FU in a group of aphakic eyes. Whether full-thickness filtration in aphakic eyes stands a higher chance of longterm success remains to be determined.

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b. SubsclerallSemi-guarded Trabeculectomy has become the surgical procedure of choice for treating various types of glaucoma, in phakic as well as aphakic eyes. The success rate in the latter group, however, is considerably lower than in the former, and the complication rate slightly modified trabec_ is higher. 135,‘39.‘40,141,143,315A ulectomy, referred to as the subscleral Scheie procedure, has been reported to give good results 83% success, according to McGuigan and coworkers.226 Luntz et a120grecommended the combination of this procedure with anterior vitrectomy. In the case of pseudophakia, special considerations and precautions have to be kept in mind. Overfiltration and flattening of the anterior chamber postoperatively can be extremely hazardous to the cornea.313 The value of a viscoelastic substance during surgery cannot be overemphasized.‘75.313 We also stress the importance of tight closure of the scleral flap in these cases in particular to avoid overfiltration. It is much safer to have to deal with underfiltration, by repeated focal massage373 and laser if needed, than to be faced with suture lysis, 150*305*372a cornea-intraocular lens touch due to overfiltration. By the same argument, we believe that full-thickness procedures should not be performed in pseudophakic eyes. c. Nonpenetrating

Trabeculectomy

In an attempt to prevent intraoperative loss of the anterior chamber and vitreous prolapse in aphakic eyes, nonpenetrating trabeculectomy was described a few years ago by Zimmerman et a1.405V406 The operation aims at excising trabecular meshwork, under a scleral flap, down to its innermost layers, which are left intact, allowing aqueous to percolate through while preserving normal anterior chamber depth at all times. The authors claim high success rates and fewer complications. One of us (KFT) has had experience with nonpenetrating trabeculectomy in several aphakic cases. In the initial postoperative period, IOP control is usually achieved quite adequately in most cases. However, it seems that the remaining thin layer of tissue that is left behind acts as a scaffold, over which tissues grow readily to close the area of filtration. Occasionally, filtration may be improved by completion of the opening with the nd : YAG laser through a gonioscopy lens, within a week postoperatively. In our opinion, such a procedure is tedious and technically demanding, and has limited success. However, it may be worth pursuing, with the addition of 5-FU injection. 3. Cyclodialysis Cyclodialysis

is a relatively

old operation,110*3’3

GLAUCOMAS

AND PSEUDOPHAKIA

97

which was abandoned for some time, but is now regaining some popularity because viscoelastic substances seem to reduce the chances of bleeding, a major threat in this procedure.7~‘35~‘75,235Although it is a relatively easy and short procedure, cyclodialysis usually has a low success rate127*20gand is unpredictable in that the cyclodialysis cleft can close suddenly and at any time, causing severe IOP elevation. It seems to be more successful in aphakic eyes that have open angles than in angle-closure,‘45,285 but is less successful than trabeculectomy.135 Isolated reports, though, speak favorably of the procedure,286 especially with the use of sodium hyaluronate’ or even under air, according to an earlier report.2’5 With cyclodialysis, there is always the possibility of overtreatment, with the risk of prolonged postoperative hypotony and its sequelae. Cycloretraction is a modification of cyclodialysis, whereby a narrow scleral flap is introduced within the cyclodialysis tract, *20gthis is supposed to improve the success rate to about 60%.

surface area for drainage. Several reports have appeared about the use of the Molten0 implant in eyes with complicated glaucomas, including aphakic eyes.‘*’ ’ ‘z28a.236-237.23R The reported success rates are variable. Minckler et al23’ reported an overall success rate of 63% with the single-plate implant in aphakic or pseudophakic eyes. Preliminary analysis of our results with the single-plate Molten0 implant reveals a success rate of about 70%, with the probability of success declining to around 50% in five years, by the life-table analysis. Whether or not the double-plate implant is going to yield higher success rates remains to be determined. The original recommendation by Molten0 was that implantation be carried out in two stages to avoid the complications of immediate postoperative hypotony.* In the first stage, only the plate is implanted, leaving the tube outside the anterior chamber (buried under conjunctiva). The second stage is carried out six to eight weeks later, at which time the tube is introduced into the anterior chamber. Molten0 also advocated a special medical regimen to minimize fibrosis around the plate, consisting of colchicine, fluphenamic acid, and oral corticosteroids.” We have had extensive experience using the single-plate (and recently also the double-plate) Molteno implant in aphakic and pseudophakic eyes with glaucoma.‘.374 In order to avoid the two-stage procedure, we have resorted to occluding the tube with a suture-ligature during a one-stage procedure. In cooperative adult patients with clear corneas, the ligature, a polypropylene suture, is placed at the tip of the tube within the anterior chamber. Then at various intervals postoperatively (a few days to two weeks), the tube is opened simply by lysing or cutting the ligating suture with argon, krypton, or occasionally nd:YAG laser (Fig. 13). Alternatively, in patients who are uncooperative or who have hazy corneas, ligature of the tube is placed outside the anterior chamber, and the suture material used is absorbable, allowing spontaneous opening of the tube. It is imperative, in our experience, to minimize as much as possible the inadvertent leakage and filtration that occurs initially around the tube. For that, a 23-gauge hypodermic needle is ideal for making the entry opening for the tube into the anterior chamber. The tube and needle happen to have the same external diameter, 0.60 mm. Our postoperative regimen of medical treatment frequently includes systemic steroids, although one cannot comment with certainty whether such treatment is of any additional benefit to topical medications. In one study 345there was no additional bene-

4. Artificial

IN APHAKIA

Drainage Implants

These drainage devices have been designed to maintain communication between the anterior chamber and the subconjunctival or sub-Tenon space, in cases where there is a high risk of scarring of the filtration fistula. Some of these devices extend to the equator or beyond, creating a large potential space for aqueous drainage. Certain implants have actual pressure-dependent valves, whereas others are simple, nonvalvular conduits.

a. The Schocket Implant A silastic tubing is inserted in the anterior chamber from one end, and the other end is attached to a scleral buckle that surrounds the globe up to 360 degrees. 3o8The Schocket implant has been used in cases of refractory glaucoma, including aphakic eyes, with favorable results reported.127,308*30g

b. The Molten0 Implant The Molten0 implant is a silastic tubing which is connected to a 13 mm polymethylmethacrylate plate. The latter is anchored to the scleral surface as far posteriorly as possible, usually behind the equator. The tube is inserted into the anterior chamber, like that of the Schocket implant, under a scleral flap, and/or covered by a patch of preserved donor sclera. I ,I I I .23fi.237.238 Like the Schocket, the Molten0 tube is an open conduit with no valve and, hence, the term “Molteno valve” is a misnomer. In addition to the original single-plate implant, there is also the doubleplate Molten0 implant, which provides a wider

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Fig. 13. Molten0 tube ligated with a polypropylene suture within the anterior chamber before (right) and after (Et@) lysis of the suture ligature with laser.

after filtering from using systemic steroids surgery. With Molten0 implants in general, we quite commonly observe fluctuations in IOP, even after the tube is open, and sometimes for months after surgery. Very often patients have to have supplementary antiglaucoma medications during that period of IOP fluctuation. Despite all precautions to prevent immediate postoperative hypotony, choroidal detachment remains our most common complication. Luckily, though, the great majority of these cases resolve spontaneously and only a small fraction require surgical drainage. The anterior chamber usually deepens spontaneously with conservative treatment (Fig. 14). Other late complications include erosion of the tube through the sclera and conjunctiva with exposure. The use of preserved sclera over and above, or instead of, the scleral flap seems to offer extra protection, especially in eyes with thin sclera. fit

c. The Krupin-Denver

Valve

This is a true valve in that it has a pressure-sensitive opening at one of its ends. The open end is implanted in the anterior chamber as usual, under a scleral flap, and the other end, which has the valve, lies totally covered by the flap itself. The valve is designed to open at a pressure between 11 and 14 mm Hg, in order to prevent immediate postoperative hypotony. Although favorable results have been reported in neovascular glaucoma,‘“” the original Krupin valve does not seem to have stood the test of time, because scarring can still occur along the edges of the scleral flap, enveloping the whole valve and impeding filtration. More recently, a newer modification of the Krupin valve has been introduced. The whole tube has been made longer so that the valve end is located under a scleral buckle type of implant that extends for 180 or more degrees around the globe, very

much like the Schocket implant, with the addition of the valve, which opens at 11 mm Hg.lg’ The overall success rate with the long Krupin-Denver valve in complicated glaucomas, including four aphakic eyes, was recently reported to be 82%, over a mean follow-up period of 21 months.‘g’

d. The Joseph Implant This implant has features similar to both the Krupin and the Schocket devices, in that it is valvecontrolled, and at the same time has a wide, bucklelike part_14’ Moreover, the tubing that goes into the anterior chamber follows the contour of the globe, hence directing the tube tip away from the cornea1 endothelium. So far, the Joseph implant has been used on a limited number of patients with promising results. D. CYCLODESTRUCTIVE

PROCEDURES

1. Cyclocryotherapy Cyclocryotherapy is a well recognized method of treating advanced, complicated cases of glaucoma that are poor candidates for other conventional 49,30,31,32,62,88.109,271,272.313.343 types of glaucoma surgery. Like other methods of cyclodestruction, cyclocryotherapy is difficult to titrate and, therefore, the results are unpredictable.20g*271~272~3’3 The response to cyclocryotherapy in aphakic eyes is generally better in the presence of an open angle.2g,30~62~37g Caprioli’j’ reported 76% success in aphakic eyes with open angles, 68% in angle-closure, and only 55% in neovascular glaucoma; visual loss was encountered in 41% of the open-angle cases, 41% of those with closed-angles, and in 70% of the eyes with neovascular glaucoma. Complications were reported to be slightly higher with 360-degree treatment. Diminution of vision is a well known complication of cyclocryotherapy,30s3’,‘3 and has been attributed to cystoid macular edema.‘02 In a prospective study,

GLAUCOMAS

IN APHAKIA AND PSEUDOPHAKIA

Left: Shallow anterior chamber due to over-filtration around the Molten0 tube. Right: Spontaneous deepening of the anterior chamber shown on the left with conservative management.

Fig. 14.

Bellows2y~“oreported 92% success (intraocular pressure less than 19 mm Hg) after cyclocryotherapy in 26 eyes with aphakia and open-angle glaucoma, followed 7 to 95 months, with minimal complications; only two eyes had persistent decrease in vision. In with excessive treatment (more than general, 270-300 degrees) the risk of phthisis bulbi becomes high, more so in eyes with neovascular glaucoma,91,:1:i.6’? and in our experience, also in eyes previously subjected to multiple surgical procedures. 2. Laser Cyclocoagulation Laser energy can be delivered to the ciliary body either directly through a widely dilated pupil (or sector iridectomy) or across the sclera (transscleral). The former technique has been described using the argon laser, whereas the latter requires the nd : YAG or ruby laser.“” (See section 1V.B.) Both techniques require retrobulbar anesthesia, and can easily be performed as clinic procedures; yet, titration of treatment is difficult. The longterm safety and efficacy of such procedures remain to be determined, although some preliminary reports speak in favor of transscleral nd : YAG laser treatment.8g”“x This procedure, however, is not without complica“0.22J.37:5 tions:’ ‘I9I 3. Therapeutic

Ultrasound

High-energy ultrasound focused on the ciliary body area has been shown to lower IOP in human eyes with refractory glaucomas. The effects of ultrasound treatment include the destruction of ciliary processes as well as localized cyclodialysis and scleral thinning in the area of treatment, leading to transscleral microfiltration.“‘~77~78~‘gAlthough some favorable results have been reported with this technique, it is still not widely used because of the prohibitive cost of the equipment involved and the

difficulty of the technique itself, not to mention possible associated complications. E. THE CHOICE

OF SURGICAL

the

TREATMENT

Glaucoma procedures that normally have high success rates in phakic eyes are, in general, much less successful in aphakia and pseudophakia. On the other hand, certain procedures like cyclocryotherapy and cyclodialysis are usually reserved for aphakic eyes because of their cataractogenic potential. The choice of a glaucoma procedure in an aphakit or pseudophakic eye depends on several factors.“4” Among these are the status of the conjunctiva, the type of cataract operation,“‘:’ (i.e., the presence of an intact vitreous face, or free vitreous in the anterior chamber, or an intact posterior capsule), the presence of iris new vessels, the number of previous operations, and consequently the extent of anterior segment distortion or damage, etc. Spaeth”“” has outlined these ocular and extraocular factors in a systematic algorithm. Chandler and Simmons’” recommended intraoperative gonioscopy after anterior chamber deepening in cases of aphakic pupillary block before deciding on the type of surgery required. Other considerations include the visual potential of the eye in question, whether or not it is the patient’s only useful eye, and the life expectancy of the patient. For example, advanced, unilateral glaucoma in an elderly patient may not warrant aggressive therapy of any sort unless he/she is one-eyed, in which case maximum medical treatment should be heavily instituted before considering surgery. This is because of the short life expectancy and high morbidity and risks of surgery in old age. On the other hand, the younger patient should not be kept on chronic treatment, especially acetazolamide or

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similar preparations, if safe and effective surgical alternatives are available. Nevertheless, in many of these aphakic patients with glaucoma, old or young, it is frequently necessary to resort to life-long medical treatment because additional glaucoma operations are either technically not possible (distorted anterior segment anatomy) or carry great morbidity (phthisis, hemorrhage, poor general health, etc.). In summary, we tend to individualize our choice of surgical procedure depending on the condition of the eye in question, that of the contralateral eye, and the general status of the patient as a whole. Trabeculectomy, for example, would be a reasonable choice in an eye with an intact posterior capsule and minimal disturbance of the anterior segment. On the other hand, an aphakic eye with frank rubeosis and vitreous filling the anterior chamber is a poor candidate for any form of traditional filtering surgery.

V. Filtering Surgery in Aphakia There is almost unanimous agreement among ophthalmic surgeons that the success rate of filtering operations in aphakia or pseudophakia is considerably lower than that generally reported for phakic eyes. 32,102,127,135,136,139,141,142,149,209,245,27’,272, 313*3’4,3’5,323 Isolated reports, though, claim equal success rates in the two groups as long as certain precautions are taken.27’~27” Success rates differ from one series to another, depending on the definition of “success.“‘27*‘35,142.143They are reported to be much lower in younger age groups,‘42,‘43,3’3 but are not influenced by factors like race or sex,314 the presence of an intraocular lens, the type of glaucoma, the performance of vitrectomy, the type of conjunctival flap, or the type of cataract extraction.‘43 Rockwood et al*” did not find age or race to be important factors in a group of aphakic (among other) eyes undergoing filtering surgery with 5-FU injection. Other reports, however, describe better success of filtration after ECCE than ICCE,272 and lower success in Blacks, and in eyes that had previous glaucoma surgery or required vitrectomy.*” The same study noted that the occurrence of postoperative flat anterior chamber was much less in aphakic than in phakic eyes, and that postoperative anterior chamber depth and IOP level were not related to the sclerostomy size nor to the number of scleral flap sutures. Schwartz and Anderson,3’4 on the other hand, indicate that the type of glaucoma is the most important factor determining success of trabeculectomy in aphakia. Van Buskirk37g also suggests that filtration may be more successful after ECCE than in eyes without posterior capsules, and that the presence of an intraocular lens does not

1991

TOMEY,

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seem to “adversely affect the course of filtering operations.” Success rates as low as 33%‘15 and 39%135*‘42have been reported, or between 60%32*2’2 and 75%,140 or as high as 84%,3’8 88%33’ or even 92%.31s Hoskins’52 reported 40% success of trabeculectomy after ICCE, which improved to 60% with 5-FU. With posterior chamber pseudophakia, the rate was also 60%, and for combined procedure, namely trabeculectomy with ECCE and intraocular lens implantation, it was 70%. With the use of 5-FU, Heuer et a114* in a pilot study reported an overall success rate of 79%. In a subsequent report,144 a 69% success rate was reported for aphakic eyes undergoing filtering surgery with 5-FU, followed up for six months; for trabeculectomy in specific the rate was 59%. In a life-table analysis of surgical outcome of 88 aphakic eyes undergoing filtering surgery (fullthickness and trabeculectomy), Rockwood et al*‘l reported 63% success (IOP 25 mm Hg or less without medications, or 2 1 mm Hg or below with medications) at two and three years postoperatively. Singh and Singh3” reported 80% success with “pretrabecular filtration” in aphakic eyes. Basically, what they describe is a limbus-based trabeculectomy done inferiorly, with a triangular scleral flap and no iridectomy. Weinreb38g reported 87% success of trabeculectomy with 5-fluorouracil in aphakit eyes. The beneficial effect of 5-FU in aphakic filtering operations has been clearly demonstrated by the Fluorouracil Filtering Surgery Study Group in their recent report.365 A. POSSIBLE RATE

REASONS

FOR LOW SUCCESS

The exact causes for poor success of filtering operations in aphakic eyes are not clearly understood,333 but several explanations have been proposed. 1. Conjunctival

Scarring

Scarring caused by the cataract operation itself may play some role in the poor success of aphakic filters ‘43,27’,272,29’.323,379 R eoperation at the original site of cataract incision is technically difficult and increases the chances of intraoperative complications, like conjunctival buttonholes, diff’culties in dissecting the scleral flap, excessive bleeding, etc.‘52,3’4 Another possibility is that the preexisting conjunctival scarring may promote further scarring. “*Jo Inferior blebs have been found by some to be associated with better success,32,143,3’4,33’but others disagree.135*‘3g,‘40 2. The Vitreous The most plausible mechanism

by which vitreous

GLAUCOMAS

IN API-IARIA

AND

PSEUDOPHAKIA

can interfere with filtration is through mechanical obstruction of the filtration fistula,“8*‘45. 27’~272~ 2g’*3’5*323*333~37g although successful filtration has been described in the presence of vitreous seen going through the fistula. 32,‘35.‘45At the same time, failure of filtration can be encountered in eyes where the vitreous face is clearly away from the site of filtration. ‘35.‘3gCertain intraoperative and postoperative precautions have been recommended to avoid vitreous prolapse.“‘~“* Alternatively, total vitrectomy has been advocated.‘40 In order for vitrectomy to be beneficial, it has to be total vitrectomy, which increases the morbidity of the procedure, even in the hands of experts. Retinal detachment and cystoid macular edema are two such hazards.14’ Moreover, in eyes with peripheral cornea1 haze or opacification, it is not possible to remove all the peripheral vitreous safely. Therefore, what is thought to be total vitrectomy may not be so, and the filtration hstula can still be blocked by the remaining peripheral skirt of vitreous. It has also been postulated that the vitreous could be exercising its negative influence on filtration through some humoral mechanism.‘3g~‘40~333 3. The Crystalline

Lens

The crystalline lens may have a beneficial effect on filtration by acting as a natural barrier against vitreous prolapse.‘3g Otherwise, a less likely mechanism would also be some humoral influence, as was suggested for the vitreous.‘3g An intraocular lens, especially posterior chamber, should also act as a barrier against the forward movement of vitreous and consequently improve success; however, this has not been our clinical impression. 4. The Aqueous

Humor

Fibroblast proliferation in vitro has been shown to be influenced by the type of aqueous humor used in the culture medium.*” Aqueous taken from normal monkey eyes seems to inhibit fibroblast proliferation, whereas that from previously operated eyes (even after paracentesis), referred to as secondary aqueous, does not interfere with fibroblast activity.*” Aqueous from glaucomatous eyes, in general, has also been found to be more supportive of fibroblast proliferation than aqueous taken from nonglaucomatous eyes. ‘3X These in vitro studies have also been correlated with the clinical success rates of filtering operations among the various categories of eyes.“” Pharmacologic modulation of fibroblast activity and the process of collagen formation are major avenues of contemporary research directed toward improving the success rate of filtering surgery in complicated glaucomas. This will be discussed in

101

Section

B below.

5. High Complication

Rate

Filtering operations in aphakic eyes are associated with higher rates of complications than in phakic eyes. 2’g,3’4 Ruderman et aI*” reported a 6.6% incidence of suprachoroidal hemorrhage after filtering surgery in aphakic eyes. Also, a higher incidence of nonexpulsive choroidal hemorrhage has been described in aphakic eyes undergoing filtering surthis is attributed to the postoperative hypotony that is encountered with the use of 5-FU, which promotes filtration. It is possible, therefore, that these postoperative complications may have some adverse effects on the longterm success of filtration, gery

with

5_FU;‘*“s’44.*9’

B. MEASURES

TO IMPROVE

1. Pharmacologic

SUCCESS

Agents

a. Anti-inflammatory Agents Suppression of postoperative inflammation and prevention of fibroblast migration and proliferation are achieved quite effectively through the use of corticosteroids.333 While topical steroid treatment is usually sufficient after uncomplicated filtering procedures in phakic eyes, more vigorous treatment may be required in complicated cases where a high failure rate is anticipated.333 Systemic steroids, according to one study did not seem to be of any additional benefit over topical treatment, whereas topical steroids were significantly more effective than no treatment in promoting the success of filtration.34.’ In another study, periocular steroid injections given at various intervals preoperatively were found to be effective in minimizing postoperative scarring and bleb failure in several categories of complicated glaucomas, including aphakic eyes. IIt%?"? Topical antiprostaglandin treatment, namely indomethacin, was not found to be of any help when tested in a prospective clinical trial in phakic eyes.2g’

b. Antimetabolites Great interest has developed recently in the use of antimetabolites as adjuncts to filtering surgery in cases where bleb failure is anticipated. Antimetabolites are known to inhibit fibroblast proliferation, in vitro, and have also been found to encourage hltering bleb formation in anima1’24 and human’42,‘44,3H9 studies. Improved success rates have been reported with the use of 5-fluorouracil (5-FU) injections following filtering surgery in complicated cases of glaucoma, including aphakia, neovascular glaucoma, and cases with repeated failure of filtration.I"2.'4~,29H,"fi5.389 The F1 uorouracil Filtering Sur-

102

Surv Ophthalmol

36 (2) September-October

that the use of gery Study Group 365 demonstrated 5-FU in conjunction with trabeculectomy in aphakit and pseudophakic eyes significantly decreased the chances of failure over a one-year period of follow up. The use of antimetabolites periocularly, however, is not without complications, such as corneal epithelial defects and ulceration, and dehiscence of the conjunctival incision.‘42~‘44~2gs~365~38g Added to that is the inconvenience of having to inject the drug daily for several days, since topical application increases the cornea1 toxicity.2g8,333 Weinreb38g was able to reduce the complications caused by 5FU by adjusting the dosage schedule according to the clinical response and to the occurrence of complications. Other antimetabolites and alternate routes of drug delivery are being developed to facilitate treatment and minimize complications.‘2’~‘6g~‘ga~333 Bleomycin has been tried in rabbits. Delivered by sustained release from a subconjunctival implant (a sponge made of polymer), this drug was found to promote filtration.‘6g Assil and Weinreb,” using subconjunctival multivesicular liposomes in rabbits, investigated the use of cytarabine hydrochloride, an inhibitor of fibroblast proliferation, which is more potent than 5-FU. Beta-aminoproprionitrile (BAPN) acts by inhibiting lysyl oxidase, an enzyme which is required for the cross-linking of collagen. p40It has been used after filtering operations in aphakia and other complicated cases.44’*242 One report describes 56% success of filtration in a group of aphakic eyes in which topical BAPN was used postoperatively. 242The main advantage of BAPN is that it is used topically as an ointment, but it may have to be used daily over a period of many months. Dpenicillamine is another agent that interferes with collagen cross-linking, and is being investigated as an adjunct to filtering surgery.333 An excellent review of wound healing in filtering surgery has been written by Skuta and Parrish.333 2. Artificial Drainage Implants The purpose of artificial drainage implants in general is (a) to prevent closure of the filtration fistula between the anterior chamber and the subconjunctival or subscleral space, and (b) in longtube implants, to shunt the flow of aqueous to a more posterior location, where there is more potential space for drainage. However, clinical experience shows that the various artificial drainage implants do not always overcome the problem of fibrous tissue proliferation and scar formation. Fibrovascular membranes in cases of neovascular glaucoma can occlude the intraocular end of the drainage tube, and scarring around the extraocular portions of the implant can still occur despite ag-

TOMEY,

1991

TRAVERSO

gressive anti-inflammatory treatment.2”7~23s It is also conceivable that vitreous in the anterior chamber should interfere with the function of drainage implants; in such cases anterior vitrectomy becomes advisable, either before or at the time of implantation. 3. Modifications of the Surgical Technique In an attempt to improve the success rate of filtering operations in aphakic eyes, various modifications of the basic surgical techniques have been proA success rate of 74% was reported posed. ‘40~2’2~226*333 in a group of aphakic eyes where partial- and fullthickness filtering procedures were combined with total vitrectomy,‘40 but the author warned against the increased risks of retinal detachment and cystoid macular edema with such practice. A combination of trabeculectomy with cyclodialysis was described by Schwab in 1986.3’3 The advantage(s) of such an approach, and why it should work better than either procedure alone remain to be determined. Full-thickness filtering surgery through the pars plana has been reported to yield 50% success, with and without medical treatment, when performed simultaneously with lensectomy and vitrectomy in eyes with neovascular glaucoma,330 or in eyes that are already aphakic.“’ Peyman et al26g reported two cases of neovascular glaucoma in aphakia, treated successfully by internal, trans-pars plana filtration, using a contact nd : YAG laser, delivered with a sapphire probe. Rodriguezzg2 described an operation for advanced glaucoma in aphakic eyes, whereby a scleral flap is introduced through a cyclodialysis cleft. The number of cases treated was small, and the follow-up period was too short to draw any definite conclusions. This procedure is mentioned just for interest, and the reader is referred to the original description by Rodrigues for more details. The subscleral Scheie procedure was discussed in Section IV.C.2.b. VI.

Conclusions

There are several mechanisms by which secondary glaucoma develops as a complication of cataract surgery in a previously nonglaucomatous eye. Therefore, the use of the term “aphakic glaucoma” has been generally discouraged, as it implies only one disease entity. It is preferable to refer to this group of conditions as “the glaucomas in aphakia (and pseudophakia).” Elucidation of the pathogenesis of IOP elevation in an aphakic eye is of utmost importance before the proper management can be initiated. Important diagnostic clues include the depth of the anterior chamber, the presence or absence of a surgical iridectomy, the appearance of the anterior chamber

GLAUCOMAS

103

IN APHAKIA AND PSEUDOPHAKIA

angle and optic nerve head, and the anterior segment as a whole. The presence of an intraocular lens may or may not play a role in the pathogenesis of the secondary glaucoma in an aphakic eye. Unless there are specific indications for surgical intervention, like pupillary block or aqueous misdirection, medical treatment should be relied upon as long as adequate IOP control can be achieved with no undue side-effects to the patient. In selected cases, it may be justified to keep the patient on lifelong antiglaucoma medications, sometimes even including carbonic anhydrase inhibitors, when other options, such as laser or surgery, are not possible. The argon laser may be usesd for trabeculoplasty in selected cases with open angles, for transpupillary coagulation of the ciliary processes, or for iridotomy in cases of pupillary block. The nd : YAG laser has proved to be even more effective for the treatment of pupillary block, either by iridotomy or by capsulotomy. It is also useful for anterior vitreolysis in aqueous misdirection, and in its free-running mode for transcleral cyclophotocoagulation. This latter modality of treatment has also been described using the ruby laser. Conventional filtering procedures in general are not as successful in aphakia as they are in phakic eyes. Conjunctival scarring, the presence of vitreous in the vicinity of the filtration fistula, changes in the quality of the aqueous humor, and the higher rate of postoperative complications that is encountered in aphakic eyes may all be contributory factors to this high failure rate. The presence of an intraocular lens may constitute an additional risk in management, but removal ofthe pseudophakos is rarely indicated, as it does not necessarily reverse the glaucomatous process and may be associated with high morbidity. The choice of treatment, whether surgical, laser, or medical, depends on several considerations, and has to be individualized according to the status of the eyes in particular and on the condition of the patient in general. Measures aimed at improving success of filtration in aphakia include modification of the surgical techniques of conventional filtering procedures, e.g., combination with vitrectomy or with cyclodialysis, placing the filtration fistula in the pars plana area instead of at the limbus, and the use of artificial drainage implants, or the use of pharmacologic adjuncts that modulate wound healing and prevent unwanted scar formation. The exact causes for poor success of filtering operations in aphakia remain unknown. Active research is currently underway to improve the chances of success, either by bypassing the mechanisms of scar formation altogether (artificial im-

plants), or by modulation of wound healing through the use of 5-fluorouracil and similar drugs. Obviously, both modalities are still far from providing the ultimate, ideal solution for this challenging problem.

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1991

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1

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1980 Wyman GJ: Glaucoma induced by air injections into the anterior chamber. Am J Ophthalmol 37:424-426, 1954 Zarzycka M, Kornacki B: The use of betarays in cases of anterior chamber epithelial ingrowth after bulbus surgery. Klin Oczna 41:401406, 1971 Zavala EY, Binder PS: The pathologic findings ofepithelial ingrowth. Arch 0phtha1mo1~8:200~2014, 1980 _ Zimmerman Tl. Kooner KS. Ford VI et al: Effectiveness of non-penetrating trabeculectomy in‘Hphakic patients with glaucoma. Ophthalmic Surg 15:44-50, 1984

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406.

study of two procedures in phakic patients Ophthalmol Surg 15:734-740, 1984

with glaucoma.

Outline I. Incidence II.

Mechanisms of Pressure Elevation A. Open-angle glacoma 1. Early postoperative period : Reversible selflimited a. Alphachymotrypsin b. Blood and other particulate material c. Viscoelastic substances d. Idiopathic (1) Trabecular Meshwork Edema (2) Angle Deformation by Sutures (3) Inflammation e. Neodymium: YAG laser posterior capsulotomy 2. Sustained, permanent IOP elevation a. Preexisting primary open-angle glaucoma b. Positive steroid response in the anterior chamber C. Vitreous d. Ghost cell glaucoma e. Irreversible trabecular meshwork damage f. Inflammation g. .Late .hemorrhage B. Closed angle 1. With pupillary block a. Air bubble b. Vitreous face c. The posterior capsule d. Intraocular lens e. Seclusio pupillae f. Silicone oil 2. Aqueous misdirection 3. Without Pupillary Block a. Inflammation, hyphema b. Prolonged anterior chamber shallowing c. Iris incarceration in the surgical incision d. Intraocular lens haptics e. Pre-existing angle closure f. Neovascular glaucoma g. Epithelial downgrowth h. Fibrous ingrowth i. Endothelial proliferation j. Proliferation of iris melanocytes across the trabecular meshwork III. Diagnostic Clues A. Anterior chamber depth B. Anterior chamber reaction C. Gonioscopic findings D. Disc appearance & other fundus findings E. Iridectomy

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F. Posterior synechiae G. Filtering bleb H. Wound dehiscence Ultrasound examination I. J. Laser iridotomy IV. Treatment A. Medical treatment B. Laser treatment 1. Argon laser 2. Neodymium : YAG laser C. Surgical treatment 1. Surgical iridectomy 2. Filtering procedures a. Full-thickness operations b. Subscleral, semi-guarded c. Nonpenetrating trabeculectomy 3. Cyclodialysis 4. Artificial drainage implants a. The Schocket implant b. The Molten0 implant c. The Krupin-Denver valve d. The Joseph implant D. Cyclodestructive procedures 1. Cyclocryotherapy 2. Laser cyclocoagulation 3. Therapeutic ultrasound E. The choice of surgical treatment V. Filtering surgery in aphakia

TOMEY,

1991

TRAVERSO

A.

Possible reasons for low success rate 1. Conjunctival scarring 2. The vitreous 3. The crystalline lens 4. The aqueous humor 5. High complication rate B. Measures to improve success 1. Pharmacologic agents a. Anti-inflammatory agents b. Antimetabolites 2. Artificial drainage implants 3. Modifications of the surgical technique VI. Conclusions This project was supported by the Research Department, King Khaled Eye Specialist Hospital, Riyadh, Kingdom of Saudi Arabia. The authors are deeply grateful to the Medical Library Staff at the King Khaled Eye Specialist Hospital for their assistance in literature review, and to Rosalina Yutuc, Nirmala Mannapperuma, Lenora Mathew and Sherry Lagamon for their most valuable assistance. The authors are also grateful to the Photography and Media Services Departments at KKESH for their valuable services. Reprint address: Karim F. Tomey, M.D., Glaucoma Service, King Khaled Eye Hospital, PO Box 7191, Riyadh 11462, Saudi Arabia. Dr. Traverso is now at the Eye Clinic, University of Genova, Italy.