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Does primary intraocular lens implantation prevent “aphakic” glaucoma in children?
Does Primary Intraocular Lens Implantation Prevent “Aphakic” Glaucoma in Children? Sanjav Asrani. MD.a Sharon Freedman. MD,a Vie Hasselblad. PhD.b Edward G. Bucklev, MD,a James Epbert, MD.c Elie Dahan. MD3 Howard Gimbel. MD,e David Tohnson. MDf Scott McClatchev. M.D.g Marshall Parks, MD& David Plaper. M.D.1 and Eduardo Maselli. MDi Purpose: Open-angle glaucoma may develop after surgery for congenital or developmental cataract with an incidence ranging from 3% to 41%. The pathogenesis of “aphakic” (open-angle) glaucoma remains unknown. Despite numerous reported clinical series (>lOOOeyes), we are unaware of any reported case of open-angle glaucoma after primary intraocular lens (IOL) implantation for congenital or developmental cataract. We decided to test the hypothesis that primary posterior chamber IOL implantation might decrease the incidence of open-angle glaucoma in children. Methods: Pseudophakic eyes were collected from surgeons who contributed data to a refractive study and who monitored intraocular pressure on a regular basis. IOL implantation was commonly performed in eyes with a cornea1 diameter >lO mm. Comparable primary data on aphakic eyes were included from 2 published studies on aphakic glaucoma, which included cornea1 diameters and the patient’s age at surgery. Glaucoma-free survival estimates for each cohort were estimated. Results: Only 1 case of glaucoma was found among 377 eyes with primary pseudophakia (mean age of patient, 5.1 f 4.7 years; mean follow-up, 3.9 f 2.7 years). There were 14 eyes (11.3%) with glaucoma among 124 aphakic eyes (mean age of patient, 2.7 * 2.6 years; mean follow-up time, 7.2 f 3.9 years). Conc/usions:We report a decreased incidence of open-angle glaucoma among eyes rendered primarily pseudophakit compared with those that remained aphakic after cataract surgery. We propose 2theories on the possible mechanism of reduction in the incidence of glaucoma in pseudophakic eyes. (J AAPOS 1999;3:33-9)
hildhood cataracts, which appear at birth or in the first few years of life, pose a serious threat to the developing visual system of a young child and must be removed to clear the visual axis. Visual rehabilitation of a young child’s eye after the removal of the crystalline lens has been a challenge for years. Current methods of compensating for the refractive power of the lens that has been removed include the use of aphakic contact lenses and, more recently, the implantation of posterior chamber
C
From tbe Duke University Eye Center’ and the Duke Clinical Ruearcb Cento;b Dwbmn, North Carolina; the Univnsily of Minnesota, Minnenpoliz, Minneroti; j’obnnncrburg South Afiicd; Calgary, Albwtne; wicbita, hh.w& tbc Nmud Medical Centn; San Diego, Califimi&; Wmbington, DCb; Indiana Uniuenity Medical Centq Indimrapolir, Indian& and Sondrio, It@ Supported in part by nn unrestricted grantjvm Reseanb to Pmvmt Blindnerr, Non Ywk3 New York. Presented in pm? nt de 2Qb Annwl Meeting of the Amerimn Assaciatimzfir Pediahic Opbtbholo~ rind Strabimncr, Tmmrto, Ontario, April 11-l 8, 1999. None ofthe autbon have onyfimuial interest in tbe matcrinlpresented in tblnumwcii>t. Submitted April 115~1999. R&rim, accepted34rly 14, 1999. Reprint request.: Sbmvn E Freedman, MD, Bar 3802 Duke Univerrtiy Medical Corm; Durbmn, NC 27710 (c-mail: frredOO~~K.duke.edu). Copyright 0 2000 by tbbeAmerican Association for Pediatric Opbtbalntology and Strabi.rmtis. 1091-8S3lROOO $12.00 + 0 iWlN01869
intraocular lenses (IOLs). Amblyopia therapy is also invariably needed. Unfortunately, open-angle glaucoma may develop in a child’s eye after the removal of a congenital or developmental cataract, threatening the vision that the family and ophthalmologist have worked so hard to foster. Openangle glaucoma after surgery for congenital and developmental cataracts is a common and challenging problem, with an incidence ranging from 3 % to 41% , depending on the series.r-4 Often, this so-called aphakic glaucoma does not appear for years following uncomplicated cataract surgery.S Some authors consider small comeal diameter, cataract type, associated ocular anomalies, young patient age at the time of cataract removal, an “older” surgical technique before automated vitrectomy, and an increasing length of follow-up after surgery as risk factors for the development of aphakic glaucoma.l-10 Although several hypotheses have been proposed, the pathogenesis of aphakit glaucoma remains unknown5J! Cataracts in infants and young children have been surgically removed for decades, but the implantation of posterior chamber IOLs in the eyes of young children at the time of cataract surgery is much more recent. After ‘the ini= tial use in children older than 3 years, primary IOL
TABLE 1. Summary Author@
of published
English language literature
on primary
IOL implantation
in eyes after surgery for congenital
No.
Age at surgery
Follow-up
77 eyes
All >2 yr
Mean, 13 mo
Hutchinson 199820 Gimbel 19971s
21 eyes 48 eyes
Mean, 14 mo Mean, 50.8 mo
Brady 199714
25 eyes
Range 12 d-22 mo All >3 yr Mean age, 8.4 yr All >l yr
Vasavada
18 eyes
Mean age, 2.3 yr range, (3 mo-5 yr) All >2 yr 6tl yr
Mean, 13.3 mo
Mean, 23 mo Mean, 2 yr Range, 6 mo-5 yr Mean, 27 mo Range, Mean, Mean, Mean.
Zwaan
199832
199730
Basti 1996rz Knight-Nanan
199622
169 eyes 21 cataracts
Crouch 19951s
24 eyes
Plager 19952s
79 eyes
Kanawati
67 eyes
All >2 yr Mean age, 4.4 yr Mean age, 8.8 yr Range 10 mo-17 yr Mean age, 5.9 yr
19 18 11 13
Mean All >7 Mean Mean
Oliver 199Ozz
eyes eyes eyes congenital cataracts 20 developmental cataracts 15 eyes
Metge 19902s Sinskey 19892s Hiles 19841s BenEzra 19831s Maida 197924
199%”
Zetterstrom 199431 Kora 19932s Markham 19922s Oahan 199017 Dahan 199017
age, 5.6 yr yr age, 2.1 yr age, 11 mo
time
Mean, 21 mo
Mean, 11.3 mo Mean, 24 mo
4-16 mo 42 mo 11.9 mo 30 mo
flange, 4-8 yr
Mean, 30 mo
4 ~3 yr
Mean. 21.4 mo
35 eyes 16 eyes
12~1 yr All >3 vr
Mean, 30 mo Mean, 36 mo
135 eyes 42 eyes 90 eyes
23 eyes ~2 yr All >l yr 3<1yr,14eyesl-2yr
Range, 6 mo-9 yr Minimum, 60 mo Range 1 mo-6 yr
implantation is now being used for even younger children with congenital and developmental cataracts, both monocular and bilateral. The effect that IOL implantation may have on the incidence of aphakic (in this case, pseudophakit) open-angle glaucoma after removal of congenital and developmental cataracts in very young children is unknown. This issue will be of increasing importance in future years, following the current trend toward IOL implantation in the eyes of younger and younger children. Despite numerous reported clinical series in the literature to date, we are unaware of any reported cases of openangle glaucoma after primary IOL implantation for congenital or developmental cataracts in the absence of preexisting anterior segment anomalies.12-32 We wanted to test the hypothesis that primary posterior chamber IOL implantation might decrease the incidence of open-angle glaucoma after the removal of congenital and developmental cataracts in children. ‘lb do so, we used both published and unpublished primary data from many surgeons and surgical centers for statistical
or developmental Comment
on glaucoma
No glaucoma among congenital cataracts No open-angle glaucoma No glaucoma found No glaucoma in congenital cataracts No open-angle glaucoma found No glaucoma found No glaucoma in complications No glaucoma found No glaucoma
found
No IOP rise reported in complications No IOP rise found No glaucoma found No IOP rise reported No glaucoma reported in complications No glaucoma reported in complications No glaucoma in complications No open-angle glaucoma No glaucoma noted in complications No open-angle glaucoma No IOP rise reported Survey paper, no IOP rise reported
analysis (see below). We are unaware analysis published to date.
SUBJECTS
cataract
of any comparable
AND METHODS
A literature review was conducted to identify all peerreviewed publications in the English language that addressed the incidence of aphakic glaucoma after the removal of congenital or developmental cataracts, as well as clinical series in which primary IOL implantation in children with congenital or developmental cataracts was reported. Information sought included the patient’s age at surgery, length of follow-up, and incidence of open-angle glaucoma (Table 1). We also analyzed a large group of pseudophakic eyes after primary IOL implantation by several experienced pediatric cataract surgeons, which was part of a large database collected by McClatchey et aP for analysis of refractive changes after primary IOL implantation in children. For each eye, we knew the patient’s age at surgery, associated ocular or systemic anomalies, length of follow-up, and
occurrence of glaucoma, if any. We contacted each surgeon who contributed cases to this database and confirmed that each one specifically followed up patients with pseudophakia at least annually, measuring intraocular pressure (IOP) and evaluating each patient for possible glaucoma. Consensus among the contributing surgeons suggested that glaucoma was suspected if the IOP was above 2 1 nm Hg on more than 1 occasion or if any obvious signs such as cornea1 edema or enlargement or optic nerve cupping (asymmetry >0.2 or cup-to-disc ratio >0.4) occurred. We also confirmed from the surgeons that primary IOL implantation was routinely performed in their practice for pediatric patients with congenital or developmental cataracts as long as the horizontal cornea1 diameter was at least 10 mm and in the absence of other ocular anomalies. Several of the surgeons indicated that they occasionally implanted primary IOLs in patients with even smaller cornea1 diameters and in the presence of associated problems such as primary persistent hyperplastic vitreous, but we carefully excluded such patients from our analysis. Other patients with obvious anterior or posterior segment anomalies, trauma, or history of congenital glaucoma were excluded. Cognizant of the heterogeneous composition of eyes in published series of pediatric aphakic eyes, specifically with regard to the inclusion of many eyes with microcornea, we wanted to create a database of aphakic eyes comparable to those included among our primary pseudophakic cases (see above).‘-4J Published series on the incidence of glaucoma in eyes rendered aphakic by modem surgical technique did not provide sufficient detail regarding individual patient age at surgery, length of follow-up, and cornea1 diameter in each specific case to allow statistical comparison with the pseudophakic eyes. We contacted the authors of 2 large published series that included comeal diameter measurement at surgery and were granted access to primary data regarding their respective pediatric patients with aphakia.jJ3 In the data provided by Parks et al,3 we included only the eyes with a horizontal cornea1 diameter >lO mm recorded at surgery. These authors had classified all eyes with a cornea1 diameter 110 mm as microcornea, and we no longer had a way to separate those eyes with cornea1 diameters of exactly 10 mm (because they were classified together with smaller corneas as microcornea). Glaucoma was considered present in this retrospective series when the clinical diagnosis was made in the patient’s office record. We assume that in addition to the elevated IOP, the patients often had other evidence of glaucomatous damage. Egbert et a133 supplied primary data from their prospective study of the incidence of aphakic glaucoma after the removal of pediatric cataracts. Available information on these patients included age at surgery, horizontal cornea1 diameter at surgery, cataract type, associated ocular anomalies, and the presence or absence of glaucoma or elevated IOP when the patients were recalled at least 5 years after the original cataract operation. In the published paper by these authors, glaucoma was defined as an IOP >21 mm
TABLE 2. Age (yr) distribution
in pseudophakic
Group
Mean
SD
Median
First quartile
Third quartile
2.73 5.06
2.65 4.70
1.99 3.50
0.40 1.50
4.51 7.13
Aphakic Pseudophakic
and aphakic databases
Hg with cup-to-disc ratio changes. Ocular hypertension was defined as an IOP >2 1 mm Hg without the cup-to-disc ratio changes. In our analysis we considered only eyes with horizontal cornea1 diameters 210 mm at surgery and patients whose cataracts were congenital or developmental, without any associated ocular abnormalities or history of trauma. We considered eyes in this database to have glaucoma according to the definition of the authors in the published paper, as well as if the recorded IOP was >2S mm Hg, because it was believed that this was an IOP at which many pediatric ophthalmologists would treat for glaucoma. The onset of glaucoma was defined as the date of the recall examination by the authors or the date of glaucoma diagnosis in the patient’s clinical records, if this latter date preceded the recall examination. All eyes with associated ocular anomalies (eg, aniridia, primary persistent hyperplastic vitreous), cases in which the cataract may have been secondary (eg, history of metabolic disease, trauma), cases in which associated systemic conditions might predispose to glaucoma (eg, Lowe syndrome), and patients with a history of congenital glaucoma were excluded from analysis. Eyes with closed-angle or pupillary block glaucoma were also excluded from all databases. Survival estimates for each cohort were estimated by the Kaplan-Meier method (product-limit method).34 The survival curve, S(t), provides an estimate of the proportion of individuals in the population who survive longer than time (t). The method incorporates information on observations that were lost to follow-up. The comparison of 2 different survival curves is made using a log-rank test. This procedure is used to test for equality of the survival curves and to produce a ~2 statistic with 1” of freedom. The large database of primary pseudophakic eyes available to us noted only eyes, not patients. We chose to proceed with the analysis of eyes rather than individual patients and used the same strategy for both aphakic and pseudophakic eyes. RESULTS On review of the literature on primary IOL implantation for congenital and developmental cataracts, which included more than 1000 eyes, we were unable to fmd a single reported case of open-angle glaucoma. The range of follow-up in these studies ranged from 11 months to 9 years (Table 1). Statistical analysis (see below) was performed using a database that included 377 eyes with primary pseudophakia, operated on by 7 surgeons at 5 different institutions. The mean age of the patients was 5.06 years at the time of surgery (Table 2). Seventy-three patients
Jotuna
36
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of AAPOS
Voluwr 4 Nznrrbcr 1 Felnxwy 2000
........
Aphakic Pseudophakic
i,
4
2
Years
6 After
Cataract
6 Surgery
eyes that remained
aphakic
TABLE 3. Follow-up databases
and aphakic
began to separate about 5 years after cataract surgery; there was a higher incidence of glaucoma in the aphakic eyes. The x1 test gave a value of 9.4 with lo of freedom and a P value of .002 1. We truncated the survival curves after 13 years because of the paucity of cases with follow-up longer than that period of time, especially among the pseudophakic eyes.
Grow Aphakic Pseudoohakic
in pseudophakic
Mean
SD
Median
First mat-tile
Third auartile
7.24 3.91
3.98
6.75
3.96
11.13
2.74
3.25
2.25
5.04
(19.4%) had surgery when aged 1 year or younger (with a mean follow-up of 6.1 years), and 55 patients (14.6%) had surgery when aged between 1 and 2 years. The mean follow-up for the entire pseudophakic group was 3.91 years (Table 3). Only a single case of open-angle glaucoma was found among this group of pseudophakic eyes. This was in a child who was operated on when aged 2 months, and the child developed glaucoma one year later. The database of aphakic eyes (without IOL implantation at surgery) included 124 patients operated on by 7 surgeons at 2 institutions using modern microsurgical techniques. The mean age of the patients at the time of cataract surgery was 2.73 years (Table 2). Fifty-three eyes (42.7%) were operated on in children aged 1 year or younger. Eleven of the 14 patients with glaucoma had undergone their cataract surgeries when aged younger than 1 year. The mean follow-up time was 7.24 years after surgery (Table 3). Fourteen of 124 aphakic eyes (11.3 %> had glaucoma during the follow-up period. Kaplan-Meier survival curves were used to model the development of glaucoma in both the pseudophakic and the aphakic eyes in our database (Figure). The curves
those
12
Kaplan-Meier plot of glaucoma-free survival in those function of time in years after cataract surgery.
time (yr) after surgery
versus
IO
that received
primary
IOL implantation,
as a
DISCUSSION The published pseudophakic data available in the English language literature essentially provided us with 1 conclusion: there was not a single reported case of open-angle glaucoma among eyes that underwent primary IOL implantation, numbering more than 1000 eyes (for congenital and developmental cataracts without associated anomalies). It is highly unusual that not a single case of open-angle glaucoma has been reported despite many surgeons operating with multiple surgical techniques from various countries. However, the mean follow-up in most of these studies was short, and most of the patients had undergone surgery when aged older than 2 years. We have compared the incidence of open-angle glaucoma after the removal of pediatric cataract with and without primary IOL implantation. Our analysis suggests a reduced incidence of glaucoma in the primary pseudophakit eyes, compared with those that remained aphakic. Ours was not a prospective, randomized trial, but rather an analysis of 2 large databases, constructed to share features considered critical for the comparison. Several qualifications to our analysis deserve further discussion.
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Aphakic glaucoma has been associated with a patient’s young age at cataract surgery, with a small cornea1 size, and with the type of cataract.1+2*3*7 It is difficult to assess each of these factors independently because they often occur together. For example, Parks et a13 noted that nuclear cataracts (commonly present at birth) occur most often in eyes with small corneas; these infants would also be most likely to undergo cataract surgery at a young age. Primary IOL implantation was routinely performed by the surgeons contributing to our pseudophakic database in eyes with horizontal cornea1 diameters 210 mm. We wanted to compare the incidence of glaucoma between pseudophakic and aphakic eyes of comparable cornea1 diameter; we excluded all aphakic eyes with horizontal cornea1 diameters ~10 mm at surgery from analysis. However, in several clinical series of aphakic glaucoma, the incidence of aphakic glaucoma was higher in eyes with microcornea than in those with “normal” cornea1 diameters.316 Parks et a13 found a 32% incidence of aphakic glaucoma among those eyes with cornea1 diameters 510 mm at surgery; by contrast, eyes with cornea1 diameters >lO mm at surgery had only a 2.9% incidence of glaucoma during the follow-up period. Therefore, a possible risk factor for postoperative glaucoma, small cornea1 diameter, was not addressed in this study. Most of our aphakic database was composed of eyes from the study by Parks et a13 (see “Methods” section above), and these were divided into eyes with corneas >lO mm and those with cornea1 diameter 510 mm (considered small by these authors). We limited our aphakic cases to those eyes with a cornea1 diameter >lO mm at surgery. We excluded &Xl% of the cases of nuclear cataracts (all except 2 cases reported with cornea1 diameters >lO mm), one of the most common types of congenital cataract. This may have led us to underestimate the incidence of aphakic glaucoma, because many surgeons would consider 10 mm as a normal cornea1 diameter in the neonate.js-37 The KaplanMeier estimation of the glaucoma incidence among the aphakic eyes included in our database suggests that glaucoma would develop in only about 25% of these eyes 13 years after cataract removal, an incidence lower than that reported in many clinical series with shorter follow-up, but which included smaller eyes.418 On the other hand, it is possible that by choosing only “normal-sized” eyes for primary IOL implantation, surgeons performing that surgery were selecting against those patients most prone to glaucoma. The association between small corneas and glaucoma is not universally reported; Simon et al4 found no association between microcornea and glaucoma development. A patient’s young age at cataract extraction has been considered another risk factor in the development of glaucorna.l,2,7,8 However, when the cataract surgery is delayed until after patients are aged 1 year, glaucoma does develop.5 In our series, we were unable to examine the effect of age on the incidence of glaucoma because of the small number of event rates in our 2 databases. We did have a
Amani et al
37
sizable proportion of eyes operated on for IOL implantation in patients who were young (73 eyes [l9.4%] in patients aged younger than 1 year). However, the age distribution of the aphakic and pseudophakic cases was different, with the latter skewed toward slightly older children (Table 2). The incidence of aphakic glaucoma is known to rise with increasing postsurgical follow-up tirne.2.+5,8 In a series of 47 patients with aphakia with a mean follow-up of 72 months, Johnson and Keech8 reported a 32% glaucoma incidence with a mean interval of 47.5 months after surgery. In a study of 32 aphakic eyes, Simon et al4 reported an overall glaucoma incidence of 24%, with the onset of most cases occurring more than 5 years after cataract surgery. Aphakic eyes included in this study were only those operated on by surgeons using the modern microsurgical techniques of lensectomy and automated vitrectomy. Although pupillary block glaucoma was common with the older techniques of cataract surgery, it is rare with the newer techniques of cataract surgery.2>7>38139According to the review of the literature on pseudophakia in children, pupillary block glaucoma is also a rarity in such eyes.12-32 Glaucoma in children with aphakia has often been diagnosed clinically by signs such as cup-to-disc changes or photophobia resulting from corneal edema, rather than by elevated IOP alone. In our pseudophakic database, the contributing surgeons prospectively scrEened for glaucoma using a threshold IOP for diagnosis ~2 1 mm Hg. This difference in diagnostic criteria for glaucoma might underestimate the incidence in aphakic versus pseudophakic eyes. The mechanism by which aphakic open-angle glaucoma occurs is unknown. Various theories have been proposed, such as increased inflammation, residual lens material, glaucoma and cataract as part of a single syndrome, and postoperative steroid use.1~2~9~39,~Simon,” as well as Gimbel et al,18 has independently proposed that a chemical vitreous component may be responsible for the development of aphakic glaucoma. We propose 2 theories by which primary IOL implantation may reduce the incidence of glaucoma. One is the chemical theory; that is, a vitreous chemical component (toxic to the trabecular meshwork) in the aphakic eye may have access to the trabecular meshwork, access that is prevented or minimized in the pseudophakic eye by the presence of the IOL. Eyes with the posterior capsule left intact during an operation involving primary IOL implantation commonly need capsulotomy. Many surgeons perform a primary posterior capsulotomy, as well as an anterior vitrectomy. In both conditions, a free edge of the posterior capsule is created, which, we propose, forms an impermeable seal with the surface of the IOL and the anterior hyaloid face. We propose that this happens rather qmcWy in the early postoperative period. In young phakic eyes, the anterior hyaloid face is very strong (Weigert’s ligament) and possibly impermeable, preventing or minimizing access of the chemical component to the trabecular
meshwork. We propose that in eyes undergoing primary IOL implantation, the seal similarly prevents or minimizes access of the chemical component to the anterior chamber. In the aphakic eyes of children, even if the posterior capsule and the anterior hyaloid face are kept intact during surgery, the seal invariably has to be broken to clear the visual axis resulting from a rapid posterior capsule opacification. This would allow easier access of the proposed chemical component to the trabecular meshwork. The second theory that we propose is a mechanical theory: the support to the trabecular meshwork is lost in aphakia, and this contributes to a disorganization or collapse of the trabecular meshwork, resulting in its diminished function as a filter and an active metabolic tissue. Placement of a posterior chamber IOL primarily after cataract removal might minimize this loss of support. Our observation of a 30% incidence of glaucoma after secondary IOL implantation in 3 5 eyes that remained aphakic after surgery for congenital and developmental cataract (Freedman SF, Buckley EG, personal unpublished results, 1998) would be consistent with either of the 2 theories mentioned above. Despite the limitations of our analysis, we report a decreased incidence of open-angle glaucoma among eyes rendered primarily pseudophakic, compared with those that remained aphakic after the removal of congenital or developmental cataracts with modem microsurgical techniques. Only a randomized, prospective trial comparing similar groups of aphakic and pseudophakic eyes would definitively determine if and to what extent primary pseudophakia is actually protective against aphakic glaucoma in these children. Children with aphakia and pseudophakia need vigilant follow-up throughout life for the possible development of glaucoma, whose mechanism remains elusive at this time. The development of a prospective multicenter international database for all children undergoing primary IOL implantation may shed further insight into the true incidence and characteristics of glaucoma in these children. We do not wish for our data analysis to serve as a defense for those surgeons wishing further reason to place primary IOLs in infants at cataract surgery.
References 1. Keech RV, Tongue AC, Scott WE. Complications after surgery for congenital and infantile cataracts. Am J Ophthalmol 1989;lOS: 136-41. 2. Mills MD, Robb RM. Glaucoma following childhood cataract surgery. J Pediatr Ophthahnol Strabismus 1994;31:355-60. 3. Parks MM, Johnson DA, Reed GW. Long term visual results and complications in children with aphakia. Ophthalmology 1993;lOO: 826-41. 4. Simon Jw, Mehta N, Simmons ST, Catalan0 RA, Lininger L. Glaucoma after pediatric lensectomy/vitrectomy. Ophthalmology 1991;98:670-4. 5. Asrani SG, Wdensky JT. Glaucoma after congenital cataract surgery. Ophthalmology 1995;102:863-7.
6. Wallace DK, Plager DA. Cornea1 diameter in childhood aphakic glaucoma. J Pediatr Ophthalmol Strabismus 1996;33:230--1. 7. Robb RM, Petersen R% Outcome of treatment for bilateral congcnital cataracrs. Ophthalmic Surg 1992;23:650-6. 8. Johnson CD, Keech RV. Prevalence of glaucoma after surgery for PHPV and infantile cataracts. J Pediatr Ophthalmol Strabismus 1996;33:14-7. 9. Chrousos GA, Parks MM, O’Neill JE Incidence of chronic glaucoma, retinal detachment and secondary membrane surgery in pediatric aphakic patients. Ophthalmology 1984;91:1238--Il. IO. Parks MM. Visual results in aphakic children. Am J Ophthalmol 1982;94:441-9. 11. Simon JW. Discussion of “Glaucoma following childhood cataract surgery.” J Pediatr Opchalmol Strabismus 1994;3 1:361. 12. Basti S, Ravishankar U, Gupta S. Results of a prospective evaluation of three methods of management of pediatric cataracts. Ophthalmology 1996;103:713-20. 13. BenEzra D, Paez JH. Congenital cataract and intraocular lenses. Am J Ophthalmol 1983;96:3 1 l-4. 14. Brady KM, Atkinson CS, Kilg LA, Hiles DA. Glaucoma after cataract extraction and posterior chamber lens implantation in children. J Cataract Retiact Surg 1997;23:669-74. IS. Crouch ERJ, Pressman SH, Crouch ER. Posterior chamber incraocular lenses: long term results in pediatric cataract patients. J Pediacr Ophthalmol Strabismus 1995;32:210-8. 16. Dahan E, Sahnenson BD. Pseudophakia in children: precautions, technique, and feasibility. J Cataract Refract Surg 1990;16:75-82. 17. Dahan E, Welsh NH, Salmenson BD. Posterior chamber implants in unilateral congenital and developmental cataracts. Eur J Implant Ref Surg 1990;2:295-302. 18. Gimbel Hv, Basd S, Ferensowicz M, DeBroff BM. Results of bilateral cataract extraction with posterior chamber intraocular lens implantation in children. Ophthalmology 1997;104:1737-43. 19. Hiles DA. Intraocular lens implantation in children with monocular cataracts. Ophthalmology 1984;91:1231-7. 20. Hutchinson AK, Wilson ME, Saunders RA. Outcomes and ocular growth rates after intraocular lens implantation in the first 2 years of life. J Cataract Refract Surg 1998;21:846-52. 21. Kanawati CA. Intraocular lens implantation in children in the West Bank and Gaza. Eye 1995;9:783-93. 22. Knight-Nanan D, O’Keefe M, Bowel1 R. Outcome and complications of intraocular lenses in children with cataract. J Cataract Refract Surg 1996;22:730-6. 23. Kora Y, Shimizu K, Inatomi M, F&ado Y, Ozawa T Eye growth after cataract extraction and intraocular lens implantation in children. Ophthalmic Surg 1993;24:467-75. 24. Maida Jw, Sheets JH. Pseudophakia in children: a review of results of eighteen implant surgeons. Ophthalmic Surg 1979;10:61-6. 25. Markham RHC, Bloom PA, Chandna A, Newcomb EH. Results of intraocular lens implantation in pediatric aphakia. Eye 1992;6: 493-8. 26. Metge P, Cohen H, Chemila JE Intercapsular implantation in children. Eur J Implant Ref Surg 1990;2:319-23. 27. Oliver M, Milstein A, Pollack A. Posterior chamber lens implantation in infants and juveniles. Eur J Implant Ref Surg 1990;2:309-14. 28. Plager DA, Lipsky SN, Snyder SK, Sprunger DT, Ellis FD, Sondhi N. Capsular management and refractive error in pediatric intraocular lenses. Ophthalmology 1997;104:600-7. 29. Sinskey RM, Karel F, Dal Ri E. Management of cataracts in children. J Cataract Refract Surg 1989;15:196-200. 30. Vasavada A, Desai J. Primary posterior capsulorrhexis with and without anterior vitrectomy in congenital cataracts. J Cataract Refract Surg 1997;23:645-51. 3 1. Zetterstrom C, Kugelberg U, Oscarson C. Cataract surgery in children with capsulorrhexis of anterior and posterior capsules and heparin-surface-modified innaocular lenses. J Cataract Refract Surg 1994;20:599-601.
32. Zwaan J, Mullaney PB, Awad A. Pediatric intraocular lens implantation. Ophthaln~ology 1998;lOS:I 12-9. 32a.McClatchey, SK, Dahan, I:, Maselli, E, Gimbci I-1, Wilson, ME, Lambert, S, ct al. The rate of myopic shift in pediatric pscudophakia. I” press. 33. Egbert JE, Wright MM, Dahlhauser W, Keithahn MAZ, Letson RD. Summers CG. A prosprctive study of ocular hypertension and glaucoma after pediatric cataract surgery. Ophthalmology 1995;102: IO9S-101. 34. Lee ET. Statistical methods for survival data analysis. Belmont(CA): Lifetime Learning Publications; 1980. 35. Elson J. Developmental abnormalities of the cornea and iris. In:
36. 37. 38. 39. 40.
26” Annual Meeting The American Association Strabismus April 12 - 16, 2000 The Hotel del Coronado San Diego, California
Taylor D, editor. Pediatric ophthalmology. Boston: Blackwell Scientific Publications, Inc; 1990. p. 168-77. Becker B, Shaffer RN. Diagnosis and therapy of the glaucomas. St I,ouis: CV Mosby, 1965. Kiskis AA, Markowitz SN, Morin JD. Comeal diameter and axial length in congenital glaucoma. Can J Ophrhalmol 1985;20:93-7. Francois J. Late results of congenital cataract surgery. Ophthalmology 1979;86:1586-98. Walton DS. Pediatric aphakic glaucoma: a study of 65 patients. Tram Am Ophthalmol Sot 1995;93:403-20. Phclps CD, Arafar NI. Open angle glaucoma following surgery for congenital cataract. Arch Ophthalmol 1977;95:1985-7.
for Pediatric Ophthalmology
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For Scientific Program & Registration Information Contad: Maria A. Schweers, CO Scientific Program Coordinator & Registrar 810 NE Keystone Drive Ankeny, IA 50021 (515) 964-7835 FAX (515) 964-7831
Association for Pediatric Ophthalmology and Strabismus Is accredited by the Accreditatlon Coundl for Continuing Medical Education to sponsor continuing medlcal educatlon for ph’@danS.
hildhood cataracts, which appear at birth or in the first few years of life, pose a serious threat to the developing visual system of a young child and must be removed to clear the visual axis. Visual rehabilitation of a young child’s eye after the removal of the crystalline lens has been a challenge for years. Current methods of compensating for the refractive power of the lens that has been removed include the use of aphakic contact lenses and, more recently, the implantation of posterior chamber
C
From tbe Duke University Eye Center’ and the Duke Clinical Ruearcb Cento;b Dwbmn, North Carolina; the Univnsily of Minnesota, Minnenpoliz, Minneroti; j’obnnncrburg South Afiicd; Calgary, Albwtne; wicbita, hh.w& tbc Nmud Medical Centn; San Diego, Califimi&; Wmbington, DCb; Indiana Uniuenity Medical Centq Indimrapolir, Indian& and Sondrio, It@ Supported in part by nn unrestricted grantjvm Reseanb to Pmvmt Blindnerr, Non Ywk3 New York. Presented in pm? nt de 2Qb Annwl Meeting of the Amerimn Assaciatimzfir Pediahic Opbtbholo~ rind Strabimncr, Tmmrto, Ontario, April 11-l 8, 1999. None ofthe autbon have onyfimuial interest in tbe matcrinlpresented in tblnumwcii>t. Submitted April 115~1999. R&rim, accepted34rly 14, 1999. Reprint request.: Sbmvn E Freedman, MD, Bar 3802 Duke Univerrtiy Medical Corm; Durbmn, NC 27710 (c-mail: frredOO~~K.duke.edu). Copyright 0 2000 by tbbeAmerican Association for Pediatric Opbtbalntology and Strabi.rmtis. 1091-8S3lROOO $12.00 + 0 iWlN01869
intraocular lenses (IOLs). Amblyopia therapy is also invariably needed. Unfortunately, open-angle glaucoma may develop in a child’s eye after the removal of a congenital or developmental cataract, threatening the vision that the family and ophthalmologist have worked so hard to foster. Openangle glaucoma after surgery for congenital and developmental cataracts is a common and challenging problem, with an incidence ranging from 3 % to 41% , depending on the series.r-4 Often, this so-called aphakic glaucoma does not appear for years following uncomplicated cataract surgery.S Some authors consider small comeal diameter, cataract type, associated ocular anomalies, young patient age at the time of cataract removal, an “older” surgical technique before automated vitrectomy, and an increasing length of follow-up after surgery as risk factors for the development of aphakic glaucoma.l-10 Although several hypotheses have been proposed, the pathogenesis of aphakit glaucoma remains unknown5J! Cataracts in infants and young children have been surgically removed for decades, but the implantation of posterior chamber IOLs in the eyes of young children at the time of cataract surgery is much more recent. After ‘the ini= tial use in children older than 3 years, primary IOL
TABLE 1. Summary Author@
of published
English language literature
on primary
IOL implantation
in eyes after surgery for congenital
No.
Age at surgery
Follow-up
77 eyes
All >2 yr
Mean, 13 mo
Hutchinson 199820 Gimbel 19971s
21 eyes 48 eyes
Mean, 14 mo Mean, 50.8 mo
Brady 199714
25 eyes
Range 12 d-22 mo All >3 yr Mean age, 8.4 yr All >l yr
Vasavada
18 eyes
Mean age, 2.3 yr range, (3 mo-5 yr) All >2 yr 6tl yr
Mean, 13.3 mo
Mean, 23 mo Mean, 2 yr Range, 6 mo-5 yr Mean, 27 mo Range, Mean, Mean, Mean.
Zwaan
199832
199730
Basti 1996rz Knight-Nanan
199622
169 eyes 21 cataracts
Crouch 19951s
24 eyes
Plager 19952s
79 eyes
Kanawati
67 eyes
All >2 yr Mean age, 4.4 yr Mean age, 8.8 yr Range 10 mo-17 yr Mean age, 5.9 yr
19 18 11 13
Mean All >7 Mean Mean
Oliver 199Ozz
eyes eyes eyes congenital cataracts 20 developmental cataracts 15 eyes
Metge 19902s Sinskey 19892s Hiles 19841s BenEzra 19831s Maida 197924
199%”
Zetterstrom 199431 Kora 19932s Markham 19922s Oahan 199017 Dahan 199017
age, 5.6 yr yr age, 2.1 yr age, 11 mo
time
Mean, 21 mo
Mean, 11.3 mo Mean, 24 mo
4-16 mo 42 mo 11.9 mo 30 mo
flange, 4-8 yr
Mean, 30 mo
4 ~3 yr
Mean. 21.4 mo
35 eyes 16 eyes
12~1 yr All >3 vr
Mean, 30 mo Mean, 36 mo
135 eyes 42 eyes 90 eyes
23 eyes ~2 yr All >l yr 3<1yr,14eyesl-2yr
Range, 6 mo-9 yr Minimum, 60 mo Range 1 mo-6 yr
implantation is now being used for even younger children with congenital and developmental cataracts, both monocular and bilateral. The effect that IOL implantation may have on the incidence of aphakic (in this case, pseudophakit) open-angle glaucoma after removal of congenital and developmental cataracts in very young children is unknown. This issue will be of increasing importance in future years, following the current trend toward IOL implantation in the eyes of younger and younger children. Despite numerous reported clinical series in the literature to date, we are unaware of any reported cases of openangle glaucoma after primary IOL implantation for congenital or developmental cataracts in the absence of preexisting anterior segment anomalies.12-32 We wanted to test the hypothesis that primary posterior chamber IOL implantation might decrease the incidence of open-angle glaucoma after the removal of congenital and developmental cataracts in children. ‘lb do so, we used both published and unpublished primary data from many surgeons and surgical centers for statistical
or developmental Comment
on glaucoma
No glaucoma among congenital cataracts No open-angle glaucoma No glaucoma found No glaucoma in congenital cataracts No open-angle glaucoma found No glaucoma found No glaucoma in complications No glaucoma found No glaucoma
found
No IOP rise reported in complications No IOP rise found No glaucoma found No IOP rise reported No glaucoma reported in complications No glaucoma reported in complications No glaucoma in complications No open-angle glaucoma No glaucoma noted in complications No open-angle glaucoma No IOP rise reported Survey paper, no IOP rise reported
analysis (see below). We are unaware analysis published to date.
SUBJECTS
cataract
of any comparable
AND METHODS
A literature review was conducted to identify all peerreviewed publications in the English language that addressed the incidence of aphakic glaucoma after the removal of congenital or developmental cataracts, as well as clinical series in which primary IOL implantation in children with congenital or developmental cataracts was reported. Information sought included the patient’s age at surgery, length of follow-up, and incidence of open-angle glaucoma (Table 1). We also analyzed a large group of pseudophakic eyes after primary IOL implantation by several experienced pediatric cataract surgeons, which was part of a large database collected by McClatchey et aP for analysis of refractive changes after primary IOL implantation in children. For each eye, we knew the patient’s age at surgery, associated ocular or systemic anomalies, length of follow-up, and
occurrence of glaucoma, if any. We contacted each surgeon who contributed cases to this database and confirmed that each one specifically followed up patients with pseudophakia at least annually, measuring intraocular pressure (IOP) and evaluating each patient for possible glaucoma. Consensus among the contributing surgeons suggested that glaucoma was suspected if the IOP was above 2 1 nm Hg on more than 1 occasion or if any obvious signs such as cornea1 edema or enlargement or optic nerve cupping (asymmetry >0.2 or cup-to-disc ratio >0.4) occurred. We also confirmed from the surgeons that primary IOL implantation was routinely performed in their practice for pediatric patients with congenital or developmental cataracts as long as the horizontal cornea1 diameter was at least 10 mm and in the absence of other ocular anomalies. Several of the surgeons indicated that they occasionally implanted primary IOLs in patients with even smaller cornea1 diameters and in the presence of associated problems such as primary persistent hyperplastic vitreous, but we carefully excluded such patients from our analysis. Other patients with obvious anterior or posterior segment anomalies, trauma, or history of congenital glaucoma were excluded. Cognizant of the heterogeneous composition of eyes in published series of pediatric aphakic eyes, specifically with regard to the inclusion of many eyes with microcornea, we wanted to create a database of aphakic eyes comparable to those included among our primary pseudophakic cases (see above).‘-4J Published series on the incidence of glaucoma in eyes rendered aphakic by modem surgical technique did not provide sufficient detail regarding individual patient age at surgery, length of follow-up, and cornea1 diameter in each specific case to allow statistical comparison with the pseudophakic eyes. We contacted the authors of 2 large published series that included comeal diameter measurement at surgery and were granted access to primary data regarding their respective pediatric patients with aphakia.jJ3 In the data provided by Parks et al,3 we included only the eyes with a horizontal cornea1 diameter >lO mm recorded at surgery. These authors had classified all eyes with a cornea1 diameter 110 mm as microcornea, and we no longer had a way to separate those eyes with cornea1 diameters of exactly 10 mm (because they were classified together with smaller corneas as microcornea). Glaucoma was considered present in this retrospective series when the clinical diagnosis was made in the patient’s office record. We assume that in addition to the elevated IOP, the patients often had other evidence of glaucomatous damage. Egbert et a133 supplied primary data from their prospective study of the incidence of aphakic glaucoma after the removal of pediatric cataracts. Available information on these patients included age at surgery, horizontal cornea1 diameter at surgery, cataract type, associated ocular anomalies, and the presence or absence of glaucoma or elevated IOP when the patients were recalled at least 5 years after the original cataract operation. In the published paper by these authors, glaucoma was defined as an IOP >21 mm
TABLE 2. Age (yr) distribution
in pseudophakic
Group
Mean
SD
Median
First quartile
Third quartile
2.73 5.06
2.65 4.70
1.99 3.50
0.40 1.50
4.51 7.13
Aphakic Pseudophakic
and aphakic databases
Hg with cup-to-disc ratio changes. Ocular hypertension was defined as an IOP >2 1 mm Hg without the cup-to-disc ratio changes. In our analysis we considered only eyes with horizontal cornea1 diameters 210 mm at surgery and patients whose cataracts were congenital or developmental, without any associated ocular abnormalities or history of trauma. We considered eyes in this database to have glaucoma according to the definition of the authors in the published paper, as well as if the recorded IOP was >2S mm Hg, because it was believed that this was an IOP at which many pediatric ophthalmologists would treat for glaucoma. The onset of glaucoma was defined as the date of the recall examination by the authors or the date of glaucoma diagnosis in the patient’s clinical records, if this latter date preceded the recall examination. All eyes with associated ocular anomalies (eg, aniridia, primary persistent hyperplastic vitreous), cases in which the cataract may have been secondary (eg, history of metabolic disease, trauma), cases in which associated systemic conditions might predispose to glaucoma (eg, Lowe syndrome), and patients with a history of congenital glaucoma were excluded from analysis. Eyes with closed-angle or pupillary block glaucoma were also excluded from all databases. Survival estimates for each cohort were estimated by the Kaplan-Meier method (product-limit method).34 The survival curve, S(t), provides an estimate of the proportion of individuals in the population who survive longer than time (t). The method incorporates information on observations that were lost to follow-up. The comparison of 2 different survival curves is made using a log-rank test. This procedure is used to test for equality of the survival curves and to produce a ~2 statistic with 1” of freedom. The large database of primary pseudophakic eyes available to us noted only eyes, not patients. We chose to proceed with the analysis of eyes rather than individual patients and used the same strategy for both aphakic and pseudophakic eyes. RESULTS On review of the literature on primary IOL implantation for congenital and developmental cataracts, which included more than 1000 eyes, we were unable to fmd a single reported case of open-angle glaucoma. The range of follow-up in these studies ranged from 11 months to 9 years (Table 1). Statistical analysis (see below) was performed using a database that included 377 eyes with primary pseudophakia, operated on by 7 surgeons at 5 different institutions. The mean age of the patients was 5.06 years at the time of surgery (Table 2). Seventy-three patients
Jotuna
36
Amani et al
of AAPOS
Voluwr 4 Nznrrbcr 1 Felnxwy 2000
........
Aphakic Pseudophakic
i,
4
2
Years
6 After
Cataract
6 Surgery
eyes that remained
aphakic
TABLE 3. Follow-up databases
and aphakic
began to separate about 5 years after cataract surgery; there was a higher incidence of glaucoma in the aphakic eyes. The x1 test gave a value of 9.4 with lo of freedom and a P value of .002 1. We truncated the survival curves after 13 years because of the paucity of cases with follow-up longer than that period of time, especially among the pseudophakic eyes.
Grow Aphakic Pseudoohakic
in pseudophakic
Mean
SD
Median
First mat-tile
Third auartile
7.24 3.91
3.98
6.75
3.96
11.13
2.74
3.25
2.25
5.04
(19.4%) had surgery when aged 1 year or younger (with a mean follow-up of 6.1 years), and 55 patients (14.6%) had surgery when aged between 1 and 2 years. The mean follow-up for the entire pseudophakic group was 3.91 years (Table 3). Only a single case of open-angle glaucoma was found among this group of pseudophakic eyes. This was in a child who was operated on when aged 2 months, and the child developed glaucoma one year later. The database of aphakic eyes (without IOL implantation at surgery) included 124 patients operated on by 7 surgeons at 2 institutions using modern microsurgical techniques. The mean age of the patients at the time of cataract surgery was 2.73 years (Table 2). Fifty-three eyes (42.7%) were operated on in children aged 1 year or younger. Eleven of the 14 patients with glaucoma had undergone their cataract surgeries when aged younger than 1 year. The mean follow-up time was 7.24 years after surgery (Table 3). Fourteen of 124 aphakic eyes (11.3 %> had glaucoma during the follow-up period. Kaplan-Meier survival curves were used to model the development of glaucoma in both the pseudophakic and the aphakic eyes in our database (Figure). The curves
those
12
Kaplan-Meier plot of glaucoma-free survival in those function of time in years after cataract surgery.
time (yr) after surgery
versus
IO
that received
primary
IOL implantation,
as a
DISCUSSION The published pseudophakic data available in the English language literature essentially provided us with 1 conclusion: there was not a single reported case of open-angle glaucoma among eyes that underwent primary IOL implantation, numbering more than 1000 eyes (for congenital and developmental cataracts without associated anomalies). It is highly unusual that not a single case of open-angle glaucoma has been reported despite many surgeons operating with multiple surgical techniques from various countries. However, the mean follow-up in most of these studies was short, and most of the patients had undergone surgery when aged older than 2 years. We have compared the incidence of open-angle glaucoma after the removal of pediatric cataract with and without primary IOL implantation. Our analysis suggests a reduced incidence of glaucoma in the primary pseudophakit eyes, compared with those that remained aphakic. Ours was not a prospective, randomized trial, but rather an analysis of 2 large databases, constructed to share features considered critical for the comparison. Several qualifications to our analysis deserve further discussion.
30un1n1of AAPOS lhlwne
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I Felnwny
2000
Aphakic glaucoma has been associated with a patient’s young age at cataract surgery, with a small cornea1 size, and with the type of cataract.1+2*3*7 It is difficult to assess each of these factors independently because they often occur together. For example, Parks et a13 noted that nuclear cataracts (commonly present at birth) occur most often in eyes with small corneas; these infants would also be most likely to undergo cataract surgery at a young age. Primary IOL implantation was routinely performed by the surgeons contributing to our pseudophakic database in eyes with horizontal cornea1 diameters 210 mm. We wanted to compare the incidence of glaucoma between pseudophakic and aphakic eyes of comparable cornea1 diameter; we excluded all aphakic eyes with horizontal cornea1 diameters ~10 mm at surgery from analysis. However, in several clinical series of aphakic glaucoma, the incidence of aphakic glaucoma was higher in eyes with microcornea than in those with “normal” cornea1 diameters.316 Parks et a13 found a 32% incidence of aphakic glaucoma among those eyes with cornea1 diameters 510 mm at surgery; by contrast, eyes with cornea1 diameters >lO mm at surgery had only a 2.9% incidence of glaucoma during the follow-up period. Therefore, a possible risk factor for postoperative glaucoma, small cornea1 diameter, was not addressed in this study. Most of our aphakic database was composed of eyes from the study by Parks et a13 (see “Methods” section above), and these were divided into eyes with corneas >lO mm and those with cornea1 diameter 510 mm (considered small by these authors). We limited our aphakic cases to those eyes with a cornea1 diameter >lO mm at surgery. We excluded &Xl% of the cases of nuclear cataracts (all except 2 cases reported with cornea1 diameters >lO mm), one of the most common types of congenital cataract. This may have led us to underestimate the incidence of aphakic glaucoma, because many surgeons would consider 10 mm as a normal cornea1 diameter in the neonate.js-37 The KaplanMeier estimation of the glaucoma incidence among the aphakic eyes included in our database suggests that glaucoma would develop in only about 25% of these eyes 13 years after cataract removal, an incidence lower than that reported in many clinical series with shorter follow-up, but which included smaller eyes.418 On the other hand, it is possible that by choosing only “normal-sized” eyes for primary IOL implantation, surgeons performing that surgery were selecting against those patients most prone to glaucoma. The association between small corneas and glaucoma is not universally reported; Simon et al4 found no association between microcornea and glaucoma development. A patient’s young age at cataract extraction has been considered another risk factor in the development of glaucorna.l,2,7,8 However, when the cataract surgery is delayed until after patients are aged 1 year, glaucoma does develop.5 In our series, we were unable to examine the effect of age on the incidence of glaucoma because of the small number of event rates in our 2 databases. We did have a
Amani et al
37
sizable proportion of eyes operated on for IOL implantation in patients who were young (73 eyes [l9.4%] in patients aged younger than 1 year). However, the age distribution of the aphakic and pseudophakic cases was different, with the latter skewed toward slightly older children (Table 2). The incidence of aphakic glaucoma is known to rise with increasing postsurgical follow-up tirne.2.+5,8 In a series of 47 patients with aphakia with a mean follow-up of 72 months, Johnson and Keech8 reported a 32% glaucoma incidence with a mean interval of 47.5 months after surgery. In a study of 32 aphakic eyes, Simon et al4 reported an overall glaucoma incidence of 24%, with the onset of most cases occurring more than 5 years after cataract surgery. Aphakic eyes included in this study were only those operated on by surgeons using the modern microsurgical techniques of lensectomy and automated vitrectomy. Although pupillary block glaucoma was common with the older techniques of cataract surgery, it is rare with the newer techniques of cataract surgery.2>7>38139According to the review of the literature on pseudophakia in children, pupillary block glaucoma is also a rarity in such eyes.12-32 Glaucoma in children with aphakia has often been diagnosed clinically by signs such as cup-to-disc changes or photophobia resulting from corneal edema, rather than by elevated IOP alone. In our pseudophakic database, the contributing surgeons prospectively scrEened for glaucoma using a threshold IOP for diagnosis ~2 1 mm Hg. This difference in diagnostic criteria for glaucoma might underestimate the incidence in aphakic versus pseudophakic eyes. The mechanism by which aphakic open-angle glaucoma occurs is unknown. Various theories have been proposed, such as increased inflammation, residual lens material, glaucoma and cataract as part of a single syndrome, and postoperative steroid use.1~2~9~39,~Simon,” as well as Gimbel et al,18 has independently proposed that a chemical vitreous component may be responsible for the development of aphakic glaucoma. We propose 2 theories by which primary IOL implantation may reduce the incidence of glaucoma. One is the chemical theory; that is, a vitreous chemical component (toxic to the trabecular meshwork) in the aphakic eye may have access to the trabecular meshwork, access that is prevented or minimized in the pseudophakic eye by the presence of the IOL. Eyes with the posterior capsule left intact during an operation involving primary IOL implantation commonly need capsulotomy. Many surgeons perform a primary posterior capsulotomy, as well as an anterior vitrectomy. In both conditions, a free edge of the posterior capsule is created, which, we propose, forms an impermeable seal with the surface of the IOL and the anterior hyaloid face. We propose that this happens rather qmcWy in the early postoperative period. In young phakic eyes, the anterior hyaloid face is very strong (Weigert’s ligament) and possibly impermeable, preventing or minimizing access of the chemical component to the trabecular
meshwork. We propose that in eyes undergoing primary IOL implantation, the seal similarly prevents or minimizes access of the chemical component to the anterior chamber. In the aphakic eyes of children, even if the posterior capsule and the anterior hyaloid face are kept intact during surgery, the seal invariably has to be broken to clear the visual axis resulting from a rapid posterior capsule opacification. This would allow easier access of the proposed chemical component to the trabecular meshwork. The second theory that we propose is a mechanical theory: the support to the trabecular meshwork is lost in aphakia, and this contributes to a disorganization or collapse of the trabecular meshwork, resulting in its diminished function as a filter and an active metabolic tissue. Placement of a posterior chamber IOL primarily after cataract removal might minimize this loss of support. Our observation of a 30% incidence of glaucoma after secondary IOL implantation in 3 5 eyes that remained aphakic after surgery for congenital and developmental cataract (Freedman SF, Buckley EG, personal unpublished results, 1998) would be consistent with either of the 2 theories mentioned above. Despite the limitations of our analysis, we report a decreased incidence of open-angle glaucoma among eyes rendered primarily pseudophakic, compared with those that remained aphakic after the removal of congenital or developmental cataracts with modem microsurgical techniques. Only a randomized, prospective trial comparing similar groups of aphakic and pseudophakic eyes would definitively determine if and to what extent primary pseudophakia is actually protective against aphakic glaucoma in these children. Children with aphakia and pseudophakia need vigilant follow-up throughout life for the possible development of glaucoma, whose mechanism remains elusive at this time. The development of a prospective multicenter international database for all children undergoing primary IOL implantation may shed further insight into the true incidence and characteristics of glaucoma in these children. We do not wish for our data analysis to serve as a defense for those surgeons wishing further reason to place primary IOLs in infants at cataract surgery.
References 1. Keech RV, Tongue AC, Scott WE. Complications after surgery for congenital and infantile cataracts. Am J Ophthalmol 1989;lOS: 136-41. 2. Mills MD, Robb RM. Glaucoma following childhood cataract surgery. J Pediatr Ophthahnol Strabismus 1994;31:355-60. 3. Parks MM, Johnson DA, Reed GW. Long term visual results and complications in children with aphakia. Ophthalmology 1993;lOO: 826-41. 4. Simon Jw, Mehta N, Simmons ST, Catalan0 RA, Lininger L. Glaucoma after pediatric lensectomy/vitrectomy. Ophthalmology 1991;98:670-4. 5. Asrani SG, Wdensky JT. Glaucoma after congenital cataract surgery. Ophthalmology 1995;102:863-7.
6. Wallace DK, Plager DA. Cornea1 diameter in childhood aphakic glaucoma. J Pediatr Ophthalmol Strabismus 1996;33:230--1. 7. Robb RM, Petersen R% Outcome of treatment for bilateral congcnital cataracrs. Ophthalmic Surg 1992;23:650-6. 8. Johnson CD, Keech RV. Prevalence of glaucoma after surgery for PHPV and infantile cataracts. J Pediatr Ophthalmol Strabismus 1996;33:14-7. 9. Chrousos GA, Parks MM, O’Neill JE Incidence of chronic glaucoma, retinal detachment and secondary membrane surgery in pediatric aphakic patients. Ophthalmology 1984;91:1238--Il. IO. Parks MM. Visual results in aphakic children. Am J Ophthalmol 1982;94:441-9. 11. Simon JW. Discussion of “Glaucoma following childhood cataract surgery.” J Pediatr Opchalmol Strabismus 1994;3 1:361. 12. Basti S, Ravishankar U, Gupta S. Results of a prospective evaluation of three methods of management of pediatric cataracts. Ophthalmology 1996;103:713-20. 13. BenEzra D, Paez JH. Congenital cataract and intraocular lenses. Am J Ophthalmol 1983;96:3 1 l-4. 14. Brady KM, Atkinson CS, Kilg LA, Hiles DA. Glaucoma after cataract extraction and posterior chamber lens implantation in children. J Cataract Retiact Surg 1997;23:669-74. IS. Crouch ERJ, Pressman SH, Crouch ER. Posterior chamber incraocular lenses: long term results in pediatric cataract patients. J Pediacr Ophthalmol Strabismus 1995;32:210-8. 16. Dahan E, Sahnenson BD. Pseudophakia in children: precautions, technique, and feasibility. J Cataract Refract Surg 1990;16:75-82. 17. Dahan E, Welsh NH, Salmenson BD. Posterior chamber implants in unilateral congenital and developmental cataracts. Eur J Implant Ref Surg 1990;2:295-302. 18. Gimbel Hv, Basd S, Ferensowicz M, DeBroff BM. Results of bilateral cataract extraction with posterior chamber intraocular lens implantation in children. Ophthalmology 1997;104:1737-43. 19. Hiles DA. Intraocular lens implantation in children with monocular cataracts. Ophthalmology 1984;91:1231-7. 20. Hutchinson AK, Wilson ME, Saunders RA. Outcomes and ocular growth rates after intraocular lens implantation in the first 2 years of life. J Cataract Refract Surg 1998;21:846-52. 21. Kanawati CA. Intraocular lens implantation in children in the West Bank and Gaza. Eye 1995;9:783-93. 22. Knight-Nanan D, O’Keefe M, Bowel1 R. Outcome and complications of intraocular lenses in children with cataract. J Cataract Refract Surg 1996;22:730-6. 23. Kora Y, Shimizu K, Inatomi M, F&ado Y, Ozawa T Eye growth after cataract extraction and intraocular lens implantation in children. Ophthalmic Surg 1993;24:467-75. 24. Maida Jw, Sheets JH. Pseudophakia in children: a review of results of eighteen implant surgeons. Ophthalmic Surg 1979;10:61-6. 25. Markham RHC, Bloom PA, Chandna A, Newcomb EH. Results of intraocular lens implantation in pediatric aphakia. Eye 1992;6: 493-8. 26. Metge P, Cohen H, Chemila JE Intercapsular implantation in children. Eur J Implant Ref Surg 1990;2:319-23. 27. Oliver M, Milstein A, Pollack A. Posterior chamber lens implantation in infants and juveniles. Eur J Implant Ref Surg 1990;2:309-14. 28. Plager DA, Lipsky SN, Snyder SK, Sprunger DT, Ellis FD, Sondhi N. Capsular management and refractive error in pediatric intraocular lenses. Ophthalmology 1997;104:600-7. 29. Sinskey RM, Karel F, Dal Ri E. Management of cataracts in children. J Cataract Refract Surg 1989;15:196-200. 30. Vasavada A, Desai J. Primary posterior capsulorrhexis with and without anterior vitrectomy in congenital cataracts. J Cataract Refract Surg 1997;23:645-51. 3 1. Zetterstrom C, Kugelberg U, Oscarson C. Cataract surgery in children with capsulorrhexis of anterior and posterior capsules and heparin-surface-modified innaocular lenses. J Cataract Refract Surg 1994;20:599-601.
32. Zwaan J, Mullaney PB, Awad A. Pediatric intraocular lens implantation. Ophthaln~ology 1998;lOS:I 12-9. 32a.McClatchey, SK, Dahan, I:, Maselli, E, Gimbci I-1, Wilson, ME, Lambert, S, ct al. The rate of myopic shift in pediatric pscudophakia. I” press. 33. Egbert JE, Wright MM, Dahlhauser W, Keithahn MAZ, Letson RD. Summers CG. A prosprctive study of ocular hypertension and glaucoma after pediatric cataract surgery. Ophthalmology 1995;102: IO9S-101. 34. Lee ET. Statistical methods for survival data analysis. Belmont(CA): Lifetime Learning Publications; 1980. 35. Elson J. Developmental abnormalities of the cornea and iris. In:
36. 37. 38. 39. 40.
26” Annual Meeting The American Association Strabismus April 12 - 16, 2000 The Hotel del Coronado San Diego, California
Taylor D, editor. Pediatric ophthalmology. Boston: Blackwell Scientific Publications, Inc; 1990. p. 168-77. Becker B, Shaffer RN. Diagnosis and therapy of the glaucomas. St I,ouis: CV Mosby, 1965. Kiskis AA, Markowitz SN, Morin JD. Comeal diameter and axial length in congenital glaucoma. Can J Ophrhalmol 1985;20:93-7. Francois J. Late results of congenital cataract surgery. Ophthalmology 1979;86:1586-98. Walton DS. Pediatric aphakic glaucoma: a study of 65 patients. Tram Am Ophthalmol Sot 1995;93:403-20. Phclps CD, Arafar NI. Open angle glaucoma following surgery for congenital cataract. Arch Ophthalmol 1977;95:1985-7.
for Pediatric Ophthalmology
Important Dates: September, 1999 September 24, 1999 January 14,200O February 28,200O March 24,200O
Registration Opens Deadline for Receipt of Abstracts Deadline for Presenters to Register Hotel Reservation Deadline Preregistration Closes
WEDNESDAY, APRIL 12 Registration Board of Directors Meeting Opening Reception
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THURSDAY, APRIL 13 Scientific Sessions/Workshops/Posters
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pm
For Scientific Program & Registration Information Contad: Maria A. Schweers, CO Scientific Program Coordinator & Registrar 810 NE Keystone Drive Ankeny, IA 50021 (515) 964-7835 FAX (515) 964-7831
Association for Pediatric Ophthalmology and Strabismus Is accredited by the Accreditatlon Coundl for Continuing Medical Education to sponsor continuing medlcal educatlon for ph’@danS.