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The Question of Ocular Tolerance to Intravitreal Liquid Silicone
The Question of Ocular Tolerance to lntravitreal Liquid Silicone A Long-term Analysis CLEMENT CHAN, MD, EDWAliD OKUN, MD
Abstract: The authors report a retrospective review of 407 eyes that received intravitreal liquid silicone between 1961 and 1984. Initial anatomical success was noted in 270 eyes (66.3%), while initial functional success was achieved in103 eyes (25.3%). Ten years postoperatively, approximately half of the eyes with initial functional success still had functional vision (49.2%). These eyes had less advanced proliferative vitreoretinopathy and fewer inferior breaks than others. Recurrent retinal detachment rather than late complications was the predominant cause of functional failure in those eyes losing functional vision in less than ten years postoperatively. Late complications were common and frequently required therapeutic intervention. lntravitrealliquid silicone was of great benefit to many monocular patients, but of little benefit to the binocular patients in our series. [Key words: cataract, functional success, glaucoma, keratopathy, late complications, liquid silicone, proliferative vitreoretinopathy (PVR), recurrent retinal detachment.] Ophthalmology 93:651-660, 1986
Intravitrealliquid silicone was first used in the treatment of retinal detachment cmnplicated by severe proliferative vitreoretinopathy by Cibis in 1961. 1•2 This concept of stripping preretinal fibrous membranes and tamponading the detached retina with liquid silicone allowed repair of cases that were previously considered hopeless. With its unique characteristics of relatively high surface tension and perfect transparency, liquid silicone was found to be an appropnate material for this task. The ·initial enthusiastic response to this therapeutic modality was greatly tempered by a high incidence of"late complications" (cataract, glaucoma, and keratopathy)
From the Department of Ophthalmology, Washington University School of Medicine, St. Louis, Missouri. Presented at an Annual Meeting of the American Academy of Ophthal· mology. Reprint requests to Edward Okun, MD, 4949 Barnes Hospital Plaza, Suite 17413 East Pavilion, St. Louis, MO 63110.
generally one to three years after silicone placement. 3- 10 For this reason, in the early 1970s Okun advocated the limitation ofintravitreal silicone surgery essentially to oneeyed individuals. 11 The introduction of vitrectomy techniques by Machemer provided an alternative approach to the treatment of retinal detachment complicated by proliferative vitreoretinopathy (PVR). In 1977, Machemer reported the successful use of vitrectomy, membrane peeling, and i11travitreal SF6 placement in PVR cases. 17 However, it soon became apparent that vitreous microsurgery alone could permanently reattach only a small number of eyes with PVR. 13 In recent years, there has been a resurgence of interest in the use of liquid silicone, particularly in conjunction with vitreous microsurgery for PVR. 14- 17 In a series of 105 eyes, Grey and Leaver reported early anatomical success in 64% of eyes, and late anatomical success in 55% with early visual improvement in 55% and late visual improvement in 40%. 18 Many surgeons now elect to leave the liquid silicone in the eye permanently. The important question of the relative therapeutic benefits of 651
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Fig 1. Ideal appearance at the end of procedure. All liquid silicone deposited in posterior vitreous space.
liquid silicone versus its adverse effects merits reevaluation. It is particularly relevant since the current technique of silicone placement often involves a total vitrectomy plus lensectomy, followed by instillation of a less viscous silicone fluid (I 000 centistokes). This allows immediate migration of the silicone into the anterior segment, thereby exposing the corneal endothelium and trabecular meshwork to potential damaging effects. Although many authors have reported late complications occurring one to five years after silicone placement, few have reported the long-term tolerance of liquid silicone for more than ten years. 10•19 We report on the status of 407 eyes in 402 patients who underwent intravitreal liquid silicone placement in this institution between 1961 and 1984. Particular attention is Pilid to those eyes that achieved functional visual success (visual acuity of counting fingers or better). Their long-term status (follow-up of ten or more years) is noteworthy. A number of these eyes were among the original group that underwent liquid silicone placement by Cibis between 1961 and 1965. In this retrospective study, we have attempted to answer the following questions: ( 1) What characteristics are present in eyes that have maintained long-term anatomical and functional success? (2) What factors contribute to late functional failure? (3) Are those eyes that have tolerated intravitreal liquid silicone on a long-term basis immune to late complications? and (4) How useful have the silicone treated eyes been over the years?
PATIENTS AND METHODS The records of 407 eyes that underwent intravitrealliquid silicone placement by Cibis and later by members of Retina Consultants Ltd., in St. Louis, between 1961 to 1984 were retrospectively reviewed. In many instances, 652
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conventional methods of treatment were attempted in these eyes before liquid silicone was utilized as a last resort. The rates of anatomical success (defined as greater than two-thirds of the retina reattached in the upright position*) and functional success (visual acuity of count fingers or better) were noted. Late complications (cataract, glaucoma, keratopathy), and recurrent retinal detachment (more than one-third of the retina redetached in the upright position) in the functionally successful group as Well as the functionally unsuccessful group (including anatomical failure) were analyzed. In addition, detailed short and long-term characteristics of the functionally successful group were carefully studied. Comparison was made between those eyes that have maintained functional vision for ten or more years with those that lost functional vision in less than ten years. During the years 1961 through 1965, Cibis injected in~ travitreal liquid silicone through a specially constructed hand-held syringe. After 1965, liquid silicone placement was accomplished via the use of a blunt #20 gauge needle connected to a mechanical footpump under the guidance of indirect ophthalmoscopy. An attempt was made to penetrate the preretinal membranes over the disc befor~ silicone injection was begun. Detailed description of this technique utilizing Dow Corning #360 Medical Fluid™ (specific gravity 0.972 and viscosity of 2000 centistokes) can be found in previous reports by Okun et al (Fig 1). 3.4 In a few cases after 1973, the same mechanical footpump was used in conjunction with vitreous microsurgery. Postoperatively, each patient was followed periodically, usually by the same surgeon. Each examination included careful assessment of the patient's visual acuity and intraocular pressure, a5 well as the condition of the COTJ?ea, anterior chamber, lens, viireous cavity, and the retma. Maintaining adequate follow-up on these silicone patients has been a challenging task, since many patients are elderly and reside in distant states.
RESULTS Intravitreal surgery utilizing liquid silicone w;ts performed on 427 eyes of 422 patients between 1961 and 1984. Adequate records of 407 eyes of 402 patients were analyzed. Of the 407 eyes, the liquid silicone procedure was performed in 394 eyes before 1973 and in 13 eyes after 1973. Of 407 eyes, 196 were aphakic, 204 were phakic, one was pseudophakic, and 6 had subluxated lenses. There were 265 males and 137 females. Age range was 3 to 83 years with an average of 52 years. A total of 125 eyes (30.7%) had undergone one conventional procedure for retinal detachment, whereas 221 eyes (54.3%) had more than one operation prior to the silicone placement. Silicone injection in conjunction with scleral buck-
* Because of the immobile nature of these retinal detachments, the usual criterion of completely reattached retina was not used to denote anatomic success. Instead, some residual inferior fluid was considered acceptable, as long as it did not occupy more than one-third of the inferior fundus.
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Fig 2. Kaplan-Meier survival curve demonstrating the survival distribution of 103 eyes with initial functional success (VA <;:: CF). Ten years after silicone placement only about 50% of eyes maintained VA <;:: CF (no. events [lost VA], 37 eyes; no. eyes censored [lost to follow-up], 66 eyes).
ling was the primary procedure in 61 eyes ( 15%). Followup of one month or greater was achieved in 334 eyes. Of the 73 eyes that were immediately lost to follow-up, only 17 had achieved initial anatomical success. The average follow-up time for the functionally successful group was 7.6 years, with a range of one month to 23.2 years. The functionally unsuccessful group (including anatomical failure) had an average follow-up of 3.4 years, ranging from one month to 6.4 years. Of the 407 eyes, 270 eyes (66.3%) achieved initial anatomical success, and 103 eyes (25.3%) achieved functional success within one month after silicone placement. Subsequent recurrent retinal detachment was present in 87 eyes (32.2% of those with initial anatomical success). Seventy-six eyes underwent surgical revision and/or reinjection of silicone. Late complications were also analyzed. They consisted of cataracts in 105 eyes (62.1 % of phakic eyes with followup of one month or greater), glaucoma in 56 eyes ( 16.8% ), and keratopathy in 41 eyes (12.3%). Of the 105 eyes which developed cataract, 33 eyes underwent cataractextraction. Of the 56 eyes which developed glaucoma, 33 were aphakic, 20 were phakic, and two had subluxated lens. All except one of the 41 eyes with keratopathy were aphakic. Enucleation was documented for 19 eyes (4. 7%) as a result of phthisis and pain. The Kaplan-Meier Survival Curve is utilized in Figure 2 to illustrate the follow-up distribution of eyes with func-
tional vision (count fingers or better) in a total of 103 eyes. At six months after silicone placement, approximately 90% still had functional vision. By ten years after the procedure, only about 50% of the eyes had functional vision (Table 1). Characteristics of those eyes that have maintained functional vision for ten years or more (group I) were compared to those which lost functional vision in less than ten years (group II). There were 18 eyes in group I, with a range of follow-up from 10 to 23.2 years. In contrast, there were 33 eyes in group II. Of the 33 eyes, 19 Table 1. Kaplan-Meier Survival Distribution of Eyes with Visual Acuity of Count Fingers or Better (VA 2 CF) Follow-Up (years)
No. Eyes at Risk (VA 2 CF)
%Survival (Kaplan-Meier)
0 0.5 1.0 2.0 5.0 8.0 10.0 15.0 20.0 23.0
103 83 69 53 30 18 18 8 3 1
100 92.8 88.1 77.1 61 .2 49.2 49.2 34.7 34.7 34.7
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Table 2. Degree of Proliferative Vitreoretinopathy (PVR) and the Location of Retinal Breaks* Group I (maintained VA> 10 yrs)
Group II (lost VA < 10 yrs)
No. Eyes(%)
No. Eyes(%)
PVR
4 (22.2) 9 (50.0) 3 (16.7) 0 (0)
7 (21.2) 6 (18.2) 7 (21.2) 10 (30.3)
Location of Breaks Inferior Superior Horizontal Giant Tears
5 (27.8) 8 (44.4) 7 (38.9) 4 (22.2)
22 (66.7) 12 (36.4) 6 (18.2) 4 (12.1)
VA = visual acuity. * 2 eyes in group I and 3 eyes in group II with giant tears had no PVR (PVR: group II> group I, x 2 = 6.10, P= 0.013, DF = 1; inferior breaks: group II> group I, x2 = 7.07, P = 0.008, DF = 1).
eyes had follow-up of greater than ten years, but lost functional vision in less than ten years. Fourteen of the 33 eyes had follow-up of less than ten years, and lost functional vision before their last visit. The rest of the 103 eyes had less than ten years of follow-up, but still had functional vision at last visit. Table 2 demonstrates the degree of PVR, locations of retinal breaks, and the presence of giant tears in the two groups. The majority of eyes in group I had PVR of D 1 category or less (72.2%). Only three eyes (16.7%) had D2 PVR. No eyes in group I had greater than D2 PVR. Two of the four eyes with giant tears in group I also had PVR. In contrast, a total of 17 eyes (51.5%) in group II had greater than D 1 PVR. This difference was found to be statistically significant with the Chi-square analysis (x 2 = 6.10, P = 0.013, DF = 1). One of the four giant tears in group II also had PVR. There were also significantly more inferiorly located retinal breaks in eyes in group II (22 eyes or 66.7%) compared to group I (five eyes or 27 .8%; x2 = 7.07, P = 0.008, DF = 1). There was no statistically significant difference in the distribution of superior and horizontal breaks between groups I and II (superior: x2 = 0.319, P = 0.57; horizontal: x2 = 2.63, P = 0.105, DF =
1).
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Table 3 enumerates the incidence oflate complications and recurrent retinal detachment within the two groups. Cataract was present in a high percentage of phakic eyes in both groups (93.8-1 00% ), whereas recurrent retinal detachment was prevalent in group II (78. 7% ). No eyes in group I had recurrent retinal detachment. No eyes in group I had recurrent retinal detachment defined as greater than one-third of the inferior retina redetached in the upright position. The development oflate complications occurred on the average sooner in group II than in group I (Table 4). Statistical analysis was performed with the student's t-test (cataract: t = 1.68, DF = 23, glaucoma: t = 1.26, DF = 11, keratopathy: t = 0.64, DF = 13). The liquid silicone was noted to be insulated behind a layer of vitreous in 9 eyes (50.0%) in group I, but in only three eyes (9 .1%) in group II. The student's t-test was used to compare the time of onset of late complications in those eyes with the liquid silicone behind the vitreous layer with those eyes where the liquid silicone was not insulated behind the vitreous barrier (cataract: t = 0.90, DF = 23; glaucoma: t = 1.99, DF = 10; keratopathy: t = 0.636, DF = 10). Causes of late functional failure are listed in Table 5. Recurrent retinal detachment caused no functional failure in any eyes in group I but in 26 eyes (78.7%) in group II. This difference between the two groups was found to be highly statistically significant with the chi-square analysis (x 2 = 28.9, P = 0.001, DF = 1). It was present with subretinal silicone in five eyes (15.2%) in group II. It induced failure along with glaucoma with or without keratopathy, and cataract in eight eyes (24.2%) in group II. Late visual failure was noted in three eyes in group I with the average time being 12 years postoperatively (glaucoma: 10 years, cataract: 15 years, and cataract: 11 years). In contrast, the average time for functional failure for group II was 4.8 years postoperatively (range, 1-10 years). Of the 407 eyes that underwent silicone placement, the best visual acuity of 20/70 was obtained in two patients. Both patients were binocular and both were in group I. Of the 18 eyes in group I, 10 were the only eyes, while 8 eyes were binocular. Of these 8 eyes, the silicone eye did not become the better eye in any case. This applied to group II as well. As a result of late complications, therapeutic intervention was necessary for six eyes (33%) in group I (cataract extraction-!, medical glaucoma therapy-4, cyclocryotherapy-1 ), and six eyes ( 18%) in group II (cataract extraction-2, medical glaucoma therapy!, enucleation-3).
Table 3. Late Complications and Recurrent Retinal Detachment (RD)
Group I (maintained VA > 10 yrs) Group II (lost VA< 10 yrs)
No. Cataract* Eyes (% Phakic)
No. Glaucoma Eyes (%)
No. Keratopathy Eyes (%)
No. Recurrent RD Eyes (%)
10 (100) 15 (93.8)
7 (38.9) 6 (18.2)
3 (16.7) 12 (36.4)
0 (0) 26 (78.7)
VA = visual acuity. * 10 eyes in group I and 16 eyes in group II were phakic.
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CASE REPORTS Case 1 (long-term success). An 80-year-old monocular aphakic woman had total retinal detachment with PVR. She underwent retinal reattachment surgery with liquid silicone injection into the left eye by Cibis in 1964. The right eye had been blind due to a previous retinal detachment. The patient was followed routinely during the subsequent years. Visual acuity was count fingers (CF) and the treated eye remained totally quiescent. The silicone always remained within the vitreous cavity. On no occasion did the silicone migrate into the anterior chamber. There was no evidence of glaucoma, keratopathy, or uveitis. The upper two-thirds of the retina stayed flat and the lower one-third was slightly elevated. The patient was able to do housework, cook, and care for herself. She died in October 1983, at age 99, almost 20 years after silicone placement. Up to the time of death, she was able to ambulate around the house and see food on her plate. The vision in her only eye had generally been undiminished over the 20-year period. Case 2 (long-term success). A 14-year-old monocular phakic male had high myopia. He presented with total retinal detachment with superior 180° giant tear and advanced PVR in the left eye in 1968. He had three previous surgical procedures for the giant tear with rolled over retina in the left eye. He also had two unsuccessful scleral buckling procedures in the left eye in 1966, leaving him blind in that eye. He underwent liquid silicone placement in the left eye in 1968, reattaching the superior retina, although the inferior one-third of the retina remained slightly elevated. One year later, a mature cataract was noted. Extracapsular cataract extraction was performed in the same year and silicone remained behind the intact posterior capsule. Visual acuity returned to 12/400 in the left eye. The phthisical right eye was enucleated in 1977. The patient successfully attended four years of college with the use of the only remaining silicone eye. Seventeen years after silicone placement, the patient still had visual acuity of count fingers in the left eye. The last examination on January 20, 1985, showed no evidence of silicone in the anterior chamber, glaucoma, or keratopathy in that eye. The patient still lives alone and works as a sales clerk in a snack bar. Case 3 (late cataract). A 62-year-old white man underwent a scleral buckling procedure in the right eye for a retinal detachment associated with a superotemporal giant tear on August 10, 1962. The left eye had a visual acuity of 20/20 and no retinal pathology. Revision of the buckle was necessary on August 21, 1962. However, the retina developed recurrent detachment with advanced PVR. Liquid silicone injection was performed by Cibis on September 21, 1962, reattaching the retina. The vision was restored to the 20/400 level. On March 23, 1963, the infected solid silicone implant was removed. The superior two-thirds of the retina continued to be attached, and there was no evidence of cataract, glaucoma, or keratopathy. The liquid silicone remained behind the lens. On March 18, 1968, mi.ld posterior subcapsular cataract in the right eye was first noted. The patient had maintained visual acuity of CF in that eye until 1977 ( 15 years after silicone injection), when dense cataract prevented an adequate view of the retina. The visual acuity decreased to hand motions in the right eye. Case 4 (late glaucoma). A 62-year-old bilateral aphakic woman presented initially with inferior retinal detachment with multiple breaks in the right eye. The left eye had been blind for seven years. She underwent a scleral buckling procedure in her right eye on October 22, 1965. However, revision of the procedure
Table 4. Average Time of Occurrence (years) for Late Complications and Recurrent Retinal Detachment (RD)*
Group I (maintained VA> 10 yrs) Group II (lost VA < 10 yrs)
Cataract
Glaucoma
Keratopathy
5.8
8.4
6.0
1.66
2.9
3.5
Recurrent RD
4.4
VA = visual acuity. * (t-test, cataract: t = 1.68, OF = 23; glaucoma: t = 1.26, OF = 11; keratopathy: t = 0.64, OF = 13).
Table 5. Causes of Functional Failure
Cataract Glaucoma Keratopathy Recurrent RD only* Recurrent RD + glaucoma,* cataract, keratopathy Recurrent RD + SR silicone*
Group I (maintained VA> 10 yrs) No. Eyes(%)
Group II (lost VA <10 yrs) No. Eyes(%)
2 (11.1) 1 (5.6) 0 (0) 0 (0)
3 (9.1) 3 (9.1) 1 (3.0) 14 (42.4)
0 (0)
8 (24.2)
0 (0)
4 (12.1)
VA = visual acuity; RD = retinal detachment; SR = subretinal. * Recurrent RD in total of 26 eyes (78.7%) in group II, none in group I. (i = 28.9, P= 0.001, OF= 1)
was necessary on three subsequent occasions. Liquid silicone replacement was performed on December 12, 1964 for recurrent retinal detachment with D1 PVR. The entire retina was reattached and visual acuity was restored to the 20/200 level. During the subsequent four years, the liquid silicone remained as a single globule behind a layer of vitreous, without evidence of glaucoma or keratopathy. In 1972, small emulsified liquid silicone globules were noted on the anterior iris surface and anterior chamber angle, associated with a rise in the intraocular pressure. Medical therapy was initiated, including topical pilocarpine, epinephrine, and oral Diamox. The intraocular pressure fluctuated and rose above 50 mmHg on occasion. Laser pupilloplasty was performed on the right eye in February 1983 so that the retina could be examined. Progressive right corneal decompensation with both epithelial and stromal edema was evident. The patient, however, continued to enjoy visual acuity at the 20/200 range until 1983, 16 years after silicone placement. In March 1983, cyclocryotherapy for uncontrolled glaucoma was performed. The intraocular pressure was brought down below 30 mmHg. Band keratopathy and a pale optic nerve were noted in the right eye. In June 1985, intraocular pressure of 8 mmHg was noted in that eye and the patient had no light perception in either eye. Case 5 (late keratopathy). A 69-year-old bilateral aphakic man presented in 1961 with recurrent retinal detachment in the left eye. He had had three scleral buckling procedures in that eye previously. Revision of the buckle was performed by Cibis on two subsequent occasions. Retinal detachment of the right eye
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Fig 3. Examples of late complications include left, silicone induced glaucoma, and right, keratopathy.
occurred in September 1961, requiring a scleral buckling procedure to that eye. The retina remained reattached with good vision since that time. A recurrent total retinal detachment with advanced PVR occurred in the left eye, requiring liquid silicone implantation on September 12, 1961. The left retina was successfully reattached except for slight inferior elevation. Visual acuity was restored to 20/25 in the right eye and CF in the left. The left eye encountered no complications until seven years after silicone placement, when keratopathy was noted. Visual acuity dropped to the hand motion level in the left eye in March 197 5, 14 years after silicone placement. Visual acuity in the right eye remains at 20/25.
DISCUSSION Late complications due to intravitreal liquid silicone have been well documented in the literature. 3- 10• 19 They include cataract, glaucoma, and keratopathy (Fig 3). These complications have been noted to occur usually within one to three years after silicone placement in the majority of affected eyes. What is not known is whether they occur to a significant frequency in those eyes that have maintained functional vision and tolerated the presence ofliquid silicone on a long-term basis. Our present study clearly shows that silicone that has remained inert in eyes for a prolonged period may still bring about late complications ten or more years after its placement. Figure 2 and Table 1 illustrate that in the passage of time, functional vision is gradually lost; after ten years, only approximately 50% of eyes still maintained functional vision. Comparing those that maintained functional vision for ten or more years (group I) with those less than ten years (group II), late complications occurred later in group I than in group II. The lack of statistical significance may be a reflection of the small sample size. The location 656
of silicone behind a "protective layer" of formed vitreous appeared to be a prominent feature in group I (Fig 1) . The vitreous barrier prevented a massive migration of silicone into the anterior segment to induce late complications. Again, the small sample size may be responsible for the lack of statistical significance in the delay of late complications by the vitreous barrier. In time, all phakic eyes in group I developed cataract, while nearly 40% and 17% developed glaucoma and keratopathy, respectively. However, recurrent retinal detachment, rather than late complications, was the predominant cause of functional failure in those eyes that lost functional vision in less than ten years (group II). Nearly 40% of eyes with initial anatomical success in our series developed recurrent retinal detachment. This was the cause of functional failure in almost 80% of all eyes in group II, occurring at an average of 4.4 years after silicone placement, while affecting none in group I. This feature was found to have high statistical significance. Since silicone has a lower specific gravity than vitreous, it has a tendency to rise to the superior vitreous cavity when the patient is in the upright position. The loss of tamponade to the inferior retina may result in progressive inferior retinal detachment. Thus, some degree of inferior retinal detachment is noted in almost all silicone-filled eyes. Eventually, the central vision is affected as the inferior detachment reaches the macula (Fig 4). The subretinal fluid may shift upward temporarily detaching the macula during sleep in the supine position. This process can be expected to progress more rapidly in eyes with more advanced preretinal traction and inferior retinal breaks. With the absence of tamponade on the inferior retina by the silicone, the contracting preretinal membranes can elevate the inferior retinal breaks, allowing superior migration of inferior subretinal fluid . Continued
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liquefaction of the residual vitreous gel also makes more fluid available for the subretinal space with the passage of time. The majority of eyes in our series had silicone placement before the availability of vitrectomy instrumentation. Thus, the elimination of preretinal membranes might have been less than ideal in many of these eyes. A total silicone fill in the vitreous cavity was not considered desirable because of the possibility of forcing silicone into the anterior segment. Eyes in group II had significantly more advanced PVR and more inferior retinal breaks than those in group I; this was consistent with the predominance of recurrent detachment in those eyes. Progressive recurrent inferior retinal detachment eventually affecting the superior retina accounted for all cases of functional failure not due to late complications in our series. Some investigators have cited retinal toxicity by silicone to be responsible for delayed visual loss not due to late complications.20- 22 However, studies by LaBelle and Okun, and others have not confirmed such retinal toxicity. 23 - 27 Some have pointed to the reduction in ERG amplitudes in animal eyes implanted with liquid silicone to be proof of retinal toxicity. 22 Other studies found no comparable ERG changesY·28 More recent studies provided mounting evidence that the electrophysiological variance is due to preexisting retinal changes and the electrical insulating effect of the liquid silicone. 29 - 31 Prompt recovery of A and B waves was noted by several investigators after the removal of the silicone. 29 - 31 Thus up to this point, there is still no absolute proof of retinal toxicity due to liquid silicone. The development of cataract is the most common late complication of intraocular silicone. Leaver et al noted some degree of clinically recognizable lens changes not present prior to surgery in 49% of phakic eyes in one year, and up to 65% in three years. 19 Cataract developed in over 60% of the phakic eyes in our series. The most common type of cataract is a combination of nuclear sclerotic and posterior subcapsular opacities. Past histological analysis has demonstrated silicone vacuoles adherent to the anterior and posterior lens surfaces, but no actual silicone invasion of the lens substance, 19 We thus agree with Leaver and Grey that the lens degeneration is not due to the toxic effect of silicone, but to the presence of silicone vacuoles on the lens surface, preventing normal metabolic exchange. 19 Although cataract formation is common, it progresses gradually. The majority of the affected eyes are not functionally incapacitated for a prolonged period. Two eyes in group I did not lose visual function until I 1 and 15 years after surgery respectively. In both eyes, there was minimal contact between the silicone and the posterior lens capsule. When cataract extraction is considered, an extracapsular procedure leaving the posterior capsule intact is most appropriate. In our series, 16.8% of eyes developed glaucoma. This compares with 15% reported by Leaver and Grey. 19 Although earlier reports have shown that almost all eyes developing glaucoma were aphakic, long-term follow-up
Fig 4. Recurrent inferior retinal detachment with fibrous proliferation at the inferior edge of silicone bubble. '
studies have indicated that the presence of the lens did not prevent the development of glaucoma (36% of eyes with glaucoma in our series were phakic). In time, emulsified foamy silicone globules were able to penetrate the "protective" lens-vitreous barrier in many eyes, inducing glaucoma. One eye in group I did not develop intractable glaucoma until 17 years after surgery, requiring cyclocryotherapy (see case 4). Histological analysis in these eyes has shown the presence of silicone-laden macrophages within the trabecular meshwork, without evidence of structural damage to the collagen fibers and endothelial lining. 19 This strongly suggests obstruction as the cause of glaucoma. The fact that glaucoma in these eyes responds well to routine medical therapy supports this observation. In our series, 12.3% of eyes developed keratopathy. It is not a coincidental finding that all but one eye with keratopathy·in our series was aphakic. Silicone was noted to be in the anterior chamber in all eyes which had keratopathy. Histological study demonstrated deposition of small silicone vacuoles with surrounding macrophages on the corneal endothelium (Fig 5). 3•4•19 Electron microscopy showed membrane-bound vacuoles within the cytoplasm of some endothelial cells without evidence of disturbanCe to the Descemet's membrane or the deep stroma. 19 Not all eyes with silicone in the anterior chamber necessarily developed keratopathy. At least five eyes in group I had evidence of emulsified silicone in the anterior chamber without corneal changes. However, when large amounts of silicone enter the anterior chamber, keratopathy is the rule. When a significant amount of silicone has migrated into the anterior chamber of a phakic eye, anterior cham657
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AC
Fig 5. Histopathologic appearance of keratopathy with deposition of fine · silicone globules on endothelium. Note macrophages surrounding these globules. AC = anterior champer; S = silicone globules; C = cornea.
ber wash-out should be performed to prevent development ofkeratopathyand glaucoma. However, once silicone enters the anterior chamber of an aphakic eye, itisvirtually impossible to remove unless the entire intraocular silicone content is removed. When k~ratopathy has developed, it is essentially Irreversible. Peiu;trating keratoplasty in these · eyes is often unsuccessful. 32 Although intravitreal liquid silicone had great benefit for many monoqliar individuals (see case reports I and 2), it had little benefit for the binocular patients in our series. Through the entire series of binocular patients (54 of 103), the silicone treated eye was actively used by only one binocular patient, while being generally ignored by the rest. In our comparison between groups I and II, we noted that the silicone treated eye had relatively shortterm benefit for the majority of patients. Almost 65% of these eyes (33/51) lost functional vision in less than five years (average, 4.8 years). On the other hand, a large number of these eyes developed glaucoma, requiring therapeutic intervention ( 13 eyes or 25.5% ), while 15 eyes (29 .4%) developed cosmetically disfiguring keratopathy. Cataract was found in almost all the phakic eyes in the two groups (23 eyes or 95.2% ). If not for the fear of silicone migration into the anterior chamber, many more of these eyes with cataract would have undergone cataract extraction. Although 19 eyes were documented for enucleation in our study, many more enucleations might have been performed but not recorded due to loss of follow~up. Therefore, we believe that the relative risks outweigh the relative benefits of intravitreal liquid silicone placement in binocular patients. With few exceptions, liquid silicone should be limited to the monocular patient whose remaining eye is threatened with visual loss due to advanced retinal detachment. 658
We believe the ideal procedure for intravitrealliquid silicone placement calls for the following conditions: (I) adequate relief of preretinal traction; (2) neatly total silicone fill within the vitreous cavity; and (3) preseQce of a physical barrier between the silicone and the anterior segment. Conditions I ap.d 2 can be fulfilled by a vitrectomy and membrane peeling procedure. Condition 3 can be fulfilled by leaving formed anterior vitreous in the ca:se ofphakic eyes 18 • 19 ; leaving the anterior lens capsule intact when lensectomy and anterior vitrectomy are necessary 14; or leaving the posterior lens capsule in place when cataract extraction is necessary before or after the silicone procedure. We agree with Gonvers and others that extensive panretinal photocoagulation is helpful in these eyes; 16 lt creates strong retina.:..RPE adhesions, resisting traCtion by the residual preretinal membranes. To reduce the chance oflate complications, we further recommend the removal of the liquid silicone two to six months after its placement when the PVR process has quieted down, unless significant vitreoretinal traction remains. This can be accomplished easily with the use ofvitrectomy insrrumentation: silicone floats to the top and exits through a small scJerotomy as balanced salt solution is infused. · Recently, inferior iridectomy has been suggested by some retinal surgeons to be useful in preventing late anterior segment complications in aphakic eyes with liquid silicone. 34 It is suspected that the inferior iris opening allows aqueous to flow forward between the silicone oil and the corneal endothelium, thus preventing keratopathy and glaucoma (R. Zivojnovic, personal communicatjon). It has also been pointed out that as a result of improved manufacturing techniques, a better grade ofliquid silicone with more uniform molecular size can be produced (VP Gabel, personal communication). Whether its use will re-
CHAN AND OKUN •
OCULAR TOLERANCE TO LIQUID SILICONE
duce the incidence of silicone emulsification and the associated late complications remains to be proven. We conclude that while liquid silicone will continue to pfay an important role in vitreoretinal surgery, its induction of late complications must not be ignored. Much work still lies ahead to improve its therapeutic effectiveness and to reduce its harmful effects.
13. Machemer R. Synopsis of Vail; third vitreous seminar March 8 to 15, 1980 in Vail, Colorado, USA. lnt Ophthalmol1980; 2:175-7. 14. Deutman AF, Eijkenboorn GJM, Fanuriakis C. A microsurgical method for the injection of intraocular silicone oil. lnt Ophthalmol1980; 2:63-9. 15. Scott JD. Use of liquid silicone in vitrectomised eyes. Dev Ophthalmol . 1981; 2:185-90. 16. Gonvers M. Temporary use of intraocular silicone oil in the treatment of detachment with massive periretinal proliferation; preliminary report. Ophthalmologica 1982; 184:210-8. 17. Constable I, Mohamed S, Tan PL. Super viscous silicone liquid in retinal surgery. Aust J Ophthalmol 1982; 10:5-11 . 18. Grey RHB, Leaver PK. Silicone oil in the treatment of massive preretinal retraction. I. Results in 105 eyes. Br J Ophthalmol1979; 63:355-60. 19. Leaver PK, Grey RHB, Garner A. Silicone oil injection in the treatment of massive preretinal retraction. II. Late complications in 93 eyes. Br J Ophthalmol1979; 63:361-7. 20. Lee PF, Donovan RH, Mukai N, et al. Intravitreous injection of silicone: an experimental study. I. Clinical picture and histology of the eye. Ann Ophthalmol1969; 1(2):15-25. 21. Mukai N, Lee PF, Schepens CL. Intravitreous injection of silicone: an experimental study. II. Histochemistry and electron microscopy. Ann Ophthalmol1972; 4:273-87. 22. Mukai N, Lee PF, Oguri M, Schepens CL. A long-term evaluation of silicone retinopathy in monkeys. Can J Ophthalmol 1975; 10:391402. 23. Labelle P, Okun E. Ocular tolerance to liquid silicone; an experimental study. Can J Ophthalmol 1972; 7:199-204. 24. Stone W Jr. Alloplasty in surgery of the eye. N Engl J Med 1958; 258: 486-90. 25. Armaly MF. Ocular tolerance to silicones. I. Replacement of aqueous and vitreous by silicone fluids. Arch Ophthalmol1962; 68:390-5. 26. Levine AM, Ellis RA. Intraocular liquid silicone implants. Am J Ophthalmol 1963; 55:939-43. 27. Meredith TA, Lindsey DT, Edelhauser HF, Goldman AI. Electroretinographic studies following vitrectomy and intraocular silicone oil injection. Br J Ophthalmol 1985; 69:254-60. 28. Ober RR, Blanks JC, Ogden TE, et al. Experimental retinal tolerance to liquid silicone. Retina 1983; 3:77-84. 29. Momirov D, van Lith GHM, Zivojnovic R. Electroretinogram and electrooculogram of eyes with intravitreously injected silicone oil. Ophthalmologica 1983; 186:183-8. 30. Frumar KD, Gregor ZJ, Carter RM, Arden GB. Electrophysiological responses after vitrectomy and intraocular tamponade. Trans Ophthalmol Soc UK 1985; 104:129-132. 31. Foerster MH, Esser J, Laqua H. Silicone oil and its influence on electrophysiologic findings. Am J Ophthalmol 1985; 99:201-6. 32. Beekhuis WH, van Rij G, Zivojnovic R. Silicone oil keratopathy: indications for keratoplasty. Br J Ophthalmol1985; 69:247-53.
ACKNOWLEDGMENTS The authors acknowledge the assistance of Steve Mandel, BA, and Mae Gordon, PhD, for the statistical analyses; also Jeanne Toma and Sue Hamilton for preparation of the manuscript.
REFERENCES 1. Cibis PA, Becker B, Okun E, Canaan S. The use of liquid silicone in retinal detachment surgery. Arch Ophthalmol1962; 68:590-9. 2. Cibis PA. Vitreous transfer and silicone injections. Trans Am Acad Ophthalmol Otolaryngol1964; 68:983-97. 3. Okun E. lntravitreal surgery utilizing liquid silicone; a long term followup. Trans Pac Coast Oto-Ophthalmol Soc 1968; 49:141-59. 4. Okun E, Arribas NP. Therapy of retinal detachment complicated by massive preretinal fibroplasia (iong-term follow-up of patients treated with intral(itrealliquid silicone). In: Symposium on Retina and Retinal Surgery; Transactions of the New Orleans Academy of Ophthalmology. StLouis: CV Mosby, 1969; 278-93. 5. Watzke RC. Silicone retinopoiesis for retinal detachment; a long-term clinical evaluation. Arch Ophthalmol1967; 77:18!)-96. 6. Cockerham WD, Schepens CL, Freeman HM. Silicone injection in retinal detachment. Arch Ophthalmol1970; 83:704-12. 7. Kanski JJ, Daniel R. lntravitreal silicone injection in retinal detachment. Br J Ophthalmol1973; 57:542-5. 8. Alexandridis E, Daniel H. Results of silicone oil injection into the vitreous. Dev Ophthalmol 1981; 2:24-7. 9. Leaver Pk, Grey RHB, Ga,rner A. Complications following silicone-oil injection. Mod Probl Ophthalmol1979; 20:290-4. 10. Haut J, Ullern M, Chermet M, Van Effenterre G. Complications of intraocular injections of silicone combined with vitrectomy. Ophthalmologica 1980; 180:29-35. 11. Okun E. The current status of silicone oil (analysis of long-term successes). In: Irvine AR, O'Mi3,1ley C. Advances in Vitreous Surgery. Springfield: Chiirles C Thomas, 1976; 518-22. 12. Machemer R. Massive periretinal proliferation: a logical approach to therapy. Trans Am Ophthalmol Soc 1977; 75:556-86.
Discussion
by Dwain G. Fuller, MD Although Cjbis introduced the use of liquid silicone for the treatment of complicated retinal detachments in 1961, most American retinal surgeons abandoned its use within a few years due to a low long-term reattachment rate, less than spectacular
From Texas Retina Associates, Dallas.
visual results in anatomically successful cases, and many early and delayed postoperative complications attributed to silicone. Pars plana vitrectomy techniques with removal of preretinal membranes and the use of intraocular inert gas, pioneered by Machemer in the eary 1970s, improved the reattachment rate in proliferative vitreoretinopathy (PVR), but significantly more than half of all cases were still failures. Parke and Aaberg dem~ onstrated in 1984 that endolaser photocoagulation and planned
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retinotomies in conjunction with pars plana vitrectomy could improve surgical success in PVR. Various pharmacologic agents have also been used intravitreally and paraocularly in conjunction with pars plana vitrectomy in an attempt to inhibit proliferation of periretinal membranes, but their use has not dramatically improved the surgical success rate in PVR. 1•2 Encouraging reports regarding the use of intraocular liquid silicone from Scott and other European retinal surgeons during the last few years have rekindled l1 new interest in the United States in the use of intraocular silicone for the treatment of PVR. These two papers contrast the original non-vitrectomy use of silicone oil as developed by Cibis with the newer approach of using silicone oil as an intraocular tamponade in conjunction with modern vitreous surgery. Chan and Okun present valuable and unique data regarding the long-term effects of silicone in 407 eyes, some ofwhich have been followed for over 20 years. It is important to realize, however, that virtually all ofthe eyes in the authors' series had silicone injection without pars plana vitrectomy and with only minimal vitreous cavity and preretinal membrane sectioning. Despite these limitations, a number of eyes fared reasonably well for many years and provided ambulatory vision for monocular patients. Close appraisal of the authors' data reveals that only 25% of all operated eyes achieved count fingers vision or better at any time following surgery. Within ten years following surgery, eyes with count fingers vision or better had fallen to only 12% of all operated eyes with adequate follow-up. Late complications were common and included the well-known four: cataract formation, corneal clouding, glaucoma, and recurrent retinal detachment. Eyes that were initial successes and which maintained functional vision for ten years or longer were, almost without exception, eyes that had less severe PVR and fewer inferior retinal breaks. Chan and Okun conclude their paper with the suggestion that intraocular silicone be reserved primarily for use in monocular patients whose only eye has an advanced stage of retinal detachment. Cox et al report anatomic and visual results in 51 consecutive PVR eyes treated with silicone after previous failure with stateof-the-art pars plana vitrectomy techniques including membrane stripping and sectioning, air-fluid reattachment, gas tamponade, endolaser, and the occasional use of retinal tacks, retinotomies, and retinal sutures. The authors achieved a final retinal reattachment rate of 65%, but a significant number of the eyes required more than one operation. Fifty-four percent of all eyes achieved count fingers vision or better following surgery, and among the anatomically successful cases, 74% of eyes returned to count fingers vision or better. Twenty nine percent of the anatomically successful cases had significant visual improvement to the level of 20/200 or better. The surgical results of Cox et al are definitely encouraging, but these authors also noted corneal decompensation, glaucoma, cataract formation, and retinal redetachment as relatively common postoperative complications. In hopes of reducing the incidence oflate postoperative problems, the authors removed the silicone from 10 of 33 anatomically successful cases and noted a 30% redetachment rate.
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Historically, most intraocular silicone has been placed with the intent to leave it in the eye as a permanent retinal tamponade. In 1985, Gonvers presented a large series of PVR eyes treated with vitrectomy techniques in conjunction with the use of silicone oil as a temporary retinal tamponade for only four to six weeks. 3 His reattachment rate with a visual acuity of at least count fingers vision six months after silicone removal was 62%. He noted a very low complication rate with this short-term use of silicone tamponade with the exception of frequent cataract formation in phakic eyes, a problem that was easily managed with conventional cataract surgery. Visual results were encouraging with 99% of the successful cases returning at 3/200 or better vision and 17% of the eyes achieving 20/100 or better vision. Gonvers believes that extensive photocoagulation at the time of silicone surgery and in the early postoperative period permits silicone removal at four to six weeks with a relatively low redetachment rate. His technique of temporary silicone tamponade may permit early enough removal of silicone to avoid most long-term complications. Based on the available scientific data, it is logical to suggest the use of intraocular liquid silicone for eyes with PVR which have failed with aggressive vitrectomy techniques including scleral buckling, endolaser, and intraocular inert gas. Since approximately 10% of patients with a retinal detachment in one eye will develop a retinal detachment in the fellow eye, I would not aqvocate limiting the use of silicone to monocular patients. 4 The ultimate solution to the vexing problem ofPVR still eludes us, but the judicious use of intraocular silicone can permit salvage of vision in a significant number of eyes otherwise doomed to blindness. Chan and Okun are to be congratulated for their PliPer which gives not only interesting historical insight into the origin of the use of intraocu~ar silicone in the treatment of complicated retinal detachments, but also gives invaluable long-term follow-up of such cases. ·Cox et al are also to be commended for their presentation which demonstrates that the use of intraocular silicone in conjunction with skillful pars plana vitrectomy techniques can provide retinal reattachment in approximately two-thirds of eyes with proliferative vitreoretinopathy. References 1. Tano Y, Chandler D, Machemer R. Treatment of intraocular proliferation with intravitreal injection of triamcinolone acetonide. Am JOphthalmol 1980; 90:810-6. 2. Blumenkranz M, Hernandez E, Ophir A, Norton EWD. 5-fluorouracil: new applications in complicated retinal detachment for an established antimetabolite. Ophthalmology 1984; 91:122-9. 3. Gonvers M. Temporary silicone oil tamponade in the management of retinal detachment with proliferative vitreoretinopathy. Am JOphthalmol 1985; 100:239-45. 4. Davis MD, Segal PP, MacCormick A The natural course followed by the fellow eye in patients with rhegmatogenous retinal detachment. In: Pruett RC, Regan CDJ, eds. Retina Congress; 25th Anniversary Meeting of the Retina Service, Massachusetts Eye and Ear Infirmary. New York: Appleton-Century-Crofts, 1972; 643-60.
Abstract: The authors report a retrospective review of 407 eyes that received intravitreal liquid silicone between 1961 and 1984. Initial anatomical success was noted in 270 eyes (66.3%), while initial functional success was achieved in103 eyes (25.3%). Ten years postoperatively, approximately half of the eyes with initial functional success still had functional vision (49.2%). These eyes had less advanced proliferative vitreoretinopathy and fewer inferior breaks than others. Recurrent retinal detachment rather than late complications was the predominant cause of functional failure in those eyes losing functional vision in less than ten years postoperatively. Late complications were common and frequently required therapeutic intervention. lntravitrealliquid silicone was of great benefit to many monocular patients, but of little benefit to the binocular patients in our series. [Key words: cataract, functional success, glaucoma, keratopathy, late complications, liquid silicone, proliferative vitreoretinopathy (PVR), recurrent retinal detachment.] Ophthalmology 93:651-660, 1986
Intravitrealliquid silicone was first used in the treatment of retinal detachment cmnplicated by severe proliferative vitreoretinopathy by Cibis in 1961. 1•2 This concept of stripping preretinal fibrous membranes and tamponading the detached retina with liquid silicone allowed repair of cases that were previously considered hopeless. With its unique characteristics of relatively high surface tension and perfect transparency, liquid silicone was found to be an appropnate material for this task. The ·initial enthusiastic response to this therapeutic modality was greatly tempered by a high incidence of"late complications" (cataract, glaucoma, and keratopathy)
From the Department of Ophthalmology, Washington University School of Medicine, St. Louis, Missouri. Presented at an Annual Meeting of the American Academy of Ophthal· mology. Reprint requests to Edward Okun, MD, 4949 Barnes Hospital Plaza, Suite 17413 East Pavilion, St. Louis, MO 63110.
generally one to three years after silicone placement. 3- 10 For this reason, in the early 1970s Okun advocated the limitation ofintravitreal silicone surgery essentially to oneeyed individuals. 11 The introduction of vitrectomy techniques by Machemer provided an alternative approach to the treatment of retinal detachment complicated by proliferative vitreoretinopathy (PVR). In 1977, Machemer reported the successful use of vitrectomy, membrane peeling, and i11travitreal SF6 placement in PVR cases. 17 However, it soon became apparent that vitreous microsurgery alone could permanently reattach only a small number of eyes with PVR. 13 In recent years, there has been a resurgence of interest in the use of liquid silicone, particularly in conjunction with vitreous microsurgery for PVR. 14- 17 In a series of 105 eyes, Grey and Leaver reported early anatomical success in 64% of eyes, and late anatomical success in 55% with early visual improvement in 55% and late visual improvement in 40%. 18 Many surgeons now elect to leave the liquid silicone in the eye permanently. The important question of the relative therapeutic benefits of 651
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Fig 1. Ideal appearance at the end of procedure. All liquid silicone deposited in posterior vitreous space.
liquid silicone versus its adverse effects merits reevaluation. It is particularly relevant since the current technique of silicone placement often involves a total vitrectomy plus lensectomy, followed by instillation of a less viscous silicone fluid (I 000 centistokes). This allows immediate migration of the silicone into the anterior segment, thereby exposing the corneal endothelium and trabecular meshwork to potential damaging effects. Although many authors have reported late complications occurring one to five years after silicone placement, few have reported the long-term tolerance of liquid silicone for more than ten years. 10•19 We report on the status of 407 eyes in 402 patients who underwent intravitreal liquid silicone placement in this institution between 1961 and 1984. Particular attention is Pilid to those eyes that achieved functional visual success (visual acuity of counting fingers or better). Their long-term status (follow-up of ten or more years) is noteworthy. A number of these eyes were among the original group that underwent liquid silicone placement by Cibis between 1961 and 1965. In this retrospective study, we have attempted to answer the following questions: ( 1) What characteristics are present in eyes that have maintained long-term anatomical and functional success? (2) What factors contribute to late functional failure? (3) Are those eyes that have tolerated intravitreal liquid silicone on a long-term basis immune to late complications? and (4) How useful have the silicone treated eyes been over the years?
PATIENTS AND METHODS The records of 407 eyes that underwent intravitrealliquid silicone placement by Cibis and later by members of Retina Consultants Ltd., in St. Louis, between 1961 to 1984 were retrospectively reviewed. In many instances, 652
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conventional methods of treatment were attempted in these eyes before liquid silicone was utilized as a last resort. The rates of anatomical success (defined as greater than two-thirds of the retina reattached in the upright position*) and functional success (visual acuity of count fingers or better) were noted. Late complications (cataract, glaucoma, keratopathy), and recurrent retinal detachment (more than one-third of the retina redetached in the upright position) in the functionally successful group as Well as the functionally unsuccessful group (including anatomical failure) were analyzed. In addition, detailed short and long-term characteristics of the functionally successful group were carefully studied. Comparison was made between those eyes that have maintained functional vision for ten or more years with those that lost functional vision in less than ten years. During the years 1961 through 1965, Cibis injected in~ travitreal liquid silicone through a specially constructed hand-held syringe. After 1965, liquid silicone placement was accomplished via the use of a blunt #20 gauge needle connected to a mechanical footpump under the guidance of indirect ophthalmoscopy. An attempt was made to penetrate the preretinal membranes over the disc befor~ silicone injection was begun. Detailed description of this technique utilizing Dow Corning #360 Medical Fluid™ (specific gravity 0.972 and viscosity of 2000 centistokes) can be found in previous reports by Okun et al (Fig 1). 3.4 In a few cases after 1973, the same mechanical footpump was used in conjunction with vitreous microsurgery. Postoperatively, each patient was followed periodically, usually by the same surgeon. Each examination included careful assessment of the patient's visual acuity and intraocular pressure, a5 well as the condition of the COTJ?ea, anterior chamber, lens, viireous cavity, and the retma. Maintaining adequate follow-up on these silicone patients has been a challenging task, since many patients are elderly and reside in distant states.
RESULTS Intravitreal surgery utilizing liquid silicone w;ts performed on 427 eyes of 422 patients between 1961 and 1984. Adequate records of 407 eyes of 402 patients were analyzed. Of the 407 eyes, the liquid silicone procedure was performed in 394 eyes before 1973 and in 13 eyes after 1973. Of 407 eyes, 196 were aphakic, 204 were phakic, one was pseudophakic, and 6 had subluxated lenses. There were 265 males and 137 females. Age range was 3 to 83 years with an average of 52 years. A total of 125 eyes (30.7%) had undergone one conventional procedure for retinal detachment, whereas 221 eyes (54.3%) had more than one operation prior to the silicone placement. Silicone injection in conjunction with scleral buck-
* Because of the immobile nature of these retinal detachments, the usual criterion of completely reattached retina was not used to denote anatomic success. Instead, some residual inferior fluid was considered acceptable, as long as it did not occupy more than one-third of the inferior fundus.
OCULAR TOLERANCE TO LIQUID SILICONE
CHAN AND OKUN •
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Fig 2. Kaplan-Meier survival curve demonstrating the survival distribution of 103 eyes with initial functional success (VA <;:: CF). Ten years after silicone placement only about 50% of eyes maintained VA <;:: CF (no. events [lost VA], 37 eyes; no. eyes censored [lost to follow-up], 66 eyes).
ling was the primary procedure in 61 eyes ( 15%). Followup of one month or greater was achieved in 334 eyes. Of the 73 eyes that were immediately lost to follow-up, only 17 had achieved initial anatomical success. The average follow-up time for the functionally successful group was 7.6 years, with a range of one month to 23.2 years. The functionally unsuccessful group (including anatomical failure) had an average follow-up of 3.4 years, ranging from one month to 6.4 years. Of the 407 eyes, 270 eyes (66.3%) achieved initial anatomical success, and 103 eyes (25.3%) achieved functional success within one month after silicone placement. Subsequent recurrent retinal detachment was present in 87 eyes (32.2% of those with initial anatomical success). Seventy-six eyes underwent surgical revision and/or reinjection of silicone. Late complications were also analyzed. They consisted of cataracts in 105 eyes (62.1 % of phakic eyes with followup of one month or greater), glaucoma in 56 eyes ( 16.8% ), and keratopathy in 41 eyes (12.3%). Of the 105 eyes which developed cataract, 33 eyes underwent cataractextraction. Of the 56 eyes which developed glaucoma, 33 were aphakic, 20 were phakic, and two had subluxated lens. All except one of the 41 eyes with keratopathy were aphakic. Enucleation was documented for 19 eyes (4. 7%) as a result of phthisis and pain. The Kaplan-Meier Survival Curve is utilized in Figure 2 to illustrate the follow-up distribution of eyes with func-
tional vision (count fingers or better) in a total of 103 eyes. At six months after silicone placement, approximately 90% still had functional vision. By ten years after the procedure, only about 50% of the eyes had functional vision (Table 1). Characteristics of those eyes that have maintained functional vision for ten years or more (group I) were compared to those which lost functional vision in less than ten years (group II). There were 18 eyes in group I, with a range of follow-up from 10 to 23.2 years. In contrast, there were 33 eyes in group II. Of the 33 eyes, 19 Table 1. Kaplan-Meier Survival Distribution of Eyes with Visual Acuity of Count Fingers or Better (VA 2 CF) Follow-Up (years)
No. Eyes at Risk (VA 2 CF)
%Survival (Kaplan-Meier)
0 0.5 1.0 2.0 5.0 8.0 10.0 15.0 20.0 23.0
103 83 69 53 30 18 18 8 3 1
100 92.8 88.1 77.1 61 .2 49.2 49.2 34.7 34.7 34.7
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Table 2. Degree of Proliferative Vitreoretinopathy (PVR) and the Location of Retinal Breaks* Group I (maintained VA> 10 yrs)
Group II (lost VA < 10 yrs)
No. Eyes(%)
No. Eyes(%)
PVR
4 (22.2) 9 (50.0) 3 (16.7) 0 (0)
7 (21.2) 6 (18.2) 7 (21.2) 10 (30.3)
Location of Breaks Inferior Superior Horizontal Giant Tears
5 (27.8) 8 (44.4) 7 (38.9) 4 (22.2)
22 (66.7) 12 (36.4) 6 (18.2) 4 (12.1)
VA = visual acuity. * 2 eyes in group I and 3 eyes in group II with giant tears had no PVR (PVR: group II> group I, x 2 = 6.10, P= 0.013, DF = 1; inferior breaks: group II> group I, x2 = 7.07, P = 0.008, DF = 1).
eyes had follow-up of greater than ten years, but lost functional vision in less than ten years. Fourteen of the 33 eyes had follow-up of less than ten years, and lost functional vision before their last visit. The rest of the 103 eyes had less than ten years of follow-up, but still had functional vision at last visit. Table 2 demonstrates the degree of PVR, locations of retinal breaks, and the presence of giant tears in the two groups. The majority of eyes in group I had PVR of D 1 category or less (72.2%). Only three eyes (16.7%) had D2 PVR. No eyes in group I had greater than D2 PVR. Two of the four eyes with giant tears in group I also had PVR. In contrast, a total of 17 eyes (51.5%) in group II had greater than D 1 PVR. This difference was found to be statistically significant with the Chi-square analysis (x 2 = 6.10, P = 0.013, DF = 1). One of the four giant tears in group II also had PVR. There were also significantly more inferiorly located retinal breaks in eyes in group II (22 eyes or 66.7%) compared to group I (five eyes or 27 .8%; x2 = 7.07, P = 0.008, DF = 1). There was no statistically significant difference in the distribution of superior and horizontal breaks between groups I and II (superior: x2 = 0.319, P = 0.57; horizontal: x2 = 2.63, P = 0.105, DF =
1).
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Table 3 enumerates the incidence oflate complications and recurrent retinal detachment within the two groups. Cataract was present in a high percentage of phakic eyes in both groups (93.8-1 00% ), whereas recurrent retinal detachment was prevalent in group II (78. 7% ). No eyes in group I had recurrent retinal detachment. No eyes in group I had recurrent retinal detachment defined as greater than one-third of the inferior retina redetached in the upright position. The development oflate complications occurred on the average sooner in group II than in group I (Table 4). Statistical analysis was performed with the student's t-test (cataract: t = 1.68, DF = 23, glaucoma: t = 1.26, DF = 11, keratopathy: t = 0.64, DF = 13). The liquid silicone was noted to be insulated behind a layer of vitreous in 9 eyes (50.0%) in group I, but in only three eyes (9 .1%) in group II. The student's t-test was used to compare the time of onset of late complications in those eyes with the liquid silicone behind the vitreous layer with those eyes where the liquid silicone was not insulated behind the vitreous barrier (cataract: t = 0.90, DF = 23; glaucoma: t = 1.99, DF = 10; keratopathy: t = 0.636, DF = 10). Causes of late functional failure are listed in Table 5. Recurrent retinal detachment caused no functional failure in any eyes in group I but in 26 eyes (78.7%) in group II. This difference between the two groups was found to be highly statistically significant with the chi-square analysis (x 2 = 28.9, P = 0.001, DF = 1). It was present with subretinal silicone in five eyes (15.2%) in group II. It induced failure along with glaucoma with or without keratopathy, and cataract in eight eyes (24.2%) in group II. Late visual failure was noted in three eyes in group I with the average time being 12 years postoperatively (glaucoma: 10 years, cataract: 15 years, and cataract: 11 years). In contrast, the average time for functional failure for group II was 4.8 years postoperatively (range, 1-10 years). Of the 407 eyes that underwent silicone placement, the best visual acuity of 20/70 was obtained in two patients. Both patients were binocular and both were in group I. Of the 18 eyes in group I, 10 were the only eyes, while 8 eyes were binocular. Of these 8 eyes, the silicone eye did not become the better eye in any case. This applied to group II as well. As a result of late complications, therapeutic intervention was necessary for six eyes (33%) in group I (cataract extraction-!, medical glaucoma therapy-4, cyclocryotherapy-1 ), and six eyes ( 18%) in group II (cataract extraction-2, medical glaucoma therapy!, enucleation-3).
Table 3. Late Complications and Recurrent Retinal Detachment (RD)
Group I (maintained VA > 10 yrs) Group II (lost VA< 10 yrs)
No. Cataract* Eyes (% Phakic)
No. Glaucoma Eyes (%)
No. Keratopathy Eyes (%)
No. Recurrent RD Eyes (%)
10 (100) 15 (93.8)
7 (38.9) 6 (18.2)
3 (16.7) 12 (36.4)
0 (0) 26 (78.7)
VA = visual acuity. * 10 eyes in group I and 16 eyes in group II were phakic.
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CASE REPORTS Case 1 (long-term success). An 80-year-old monocular aphakic woman had total retinal detachment with PVR. She underwent retinal reattachment surgery with liquid silicone injection into the left eye by Cibis in 1964. The right eye had been blind due to a previous retinal detachment. The patient was followed routinely during the subsequent years. Visual acuity was count fingers (CF) and the treated eye remained totally quiescent. The silicone always remained within the vitreous cavity. On no occasion did the silicone migrate into the anterior chamber. There was no evidence of glaucoma, keratopathy, or uveitis. The upper two-thirds of the retina stayed flat and the lower one-third was slightly elevated. The patient was able to do housework, cook, and care for herself. She died in October 1983, at age 99, almost 20 years after silicone placement. Up to the time of death, she was able to ambulate around the house and see food on her plate. The vision in her only eye had generally been undiminished over the 20-year period. Case 2 (long-term success). A 14-year-old monocular phakic male had high myopia. He presented with total retinal detachment with superior 180° giant tear and advanced PVR in the left eye in 1968. He had three previous surgical procedures for the giant tear with rolled over retina in the left eye. He also had two unsuccessful scleral buckling procedures in the left eye in 1966, leaving him blind in that eye. He underwent liquid silicone placement in the left eye in 1968, reattaching the superior retina, although the inferior one-third of the retina remained slightly elevated. One year later, a mature cataract was noted. Extracapsular cataract extraction was performed in the same year and silicone remained behind the intact posterior capsule. Visual acuity returned to 12/400 in the left eye. The phthisical right eye was enucleated in 1977. The patient successfully attended four years of college with the use of the only remaining silicone eye. Seventeen years after silicone placement, the patient still had visual acuity of count fingers in the left eye. The last examination on January 20, 1985, showed no evidence of silicone in the anterior chamber, glaucoma, or keratopathy in that eye. The patient still lives alone and works as a sales clerk in a snack bar. Case 3 (late cataract). A 62-year-old white man underwent a scleral buckling procedure in the right eye for a retinal detachment associated with a superotemporal giant tear on August 10, 1962. The left eye had a visual acuity of 20/20 and no retinal pathology. Revision of the buckle was necessary on August 21, 1962. However, the retina developed recurrent detachment with advanced PVR. Liquid silicone injection was performed by Cibis on September 21, 1962, reattaching the retina. The vision was restored to the 20/400 level. On March 23, 1963, the infected solid silicone implant was removed. The superior two-thirds of the retina continued to be attached, and there was no evidence of cataract, glaucoma, or keratopathy. The liquid silicone remained behind the lens. On March 18, 1968, mi.ld posterior subcapsular cataract in the right eye was first noted. The patient had maintained visual acuity of CF in that eye until 1977 ( 15 years after silicone injection), when dense cataract prevented an adequate view of the retina. The visual acuity decreased to hand motions in the right eye. Case 4 (late glaucoma). A 62-year-old bilateral aphakic woman presented initially with inferior retinal detachment with multiple breaks in the right eye. The left eye had been blind for seven years. She underwent a scleral buckling procedure in her right eye on October 22, 1965. However, revision of the procedure
Table 4. Average Time of Occurrence (years) for Late Complications and Recurrent Retinal Detachment (RD)*
Group I (maintained VA> 10 yrs) Group II (lost VA < 10 yrs)
Cataract
Glaucoma
Keratopathy
5.8
8.4
6.0
1.66
2.9
3.5
Recurrent RD
4.4
VA = visual acuity. * (t-test, cataract: t = 1.68, OF = 23; glaucoma: t = 1.26, OF = 11; keratopathy: t = 0.64, OF = 13).
Table 5. Causes of Functional Failure
Cataract Glaucoma Keratopathy Recurrent RD only* Recurrent RD + glaucoma,* cataract, keratopathy Recurrent RD + SR silicone*
Group I (maintained VA> 10 yrs) No. Eyes(%)
Group II (lost VA <10 yrs) No. Eyes(%)
2 (11.1) 1 (5.6) 0 (0) 0 (0)
3 (9.1) 3 (9.1) 1 (3.0) 14 (42.4)
0 (0)
8 (24.2)
0 (0)
4 (12.1)
VA = visual acuity; RD = retinal detachment; SR = subretinal. * Recurrent RD in total of 26 eyes (78.7%) in group II, none in group I. (i = 28.9, P= 0.001, OF= 1)
was necessary on three subsequent occasions. Liquid silicone replacement was performed on December 12, 1964 for recurrent retinal detachment with D1 PVR. The entire retina was reattached and visual acuity was restored to the 20/200 level. During the subsequent four years, the liquid silicone remained as a single globule behind a layer of vitreous, without evidence of glaucoma or keratopathy. In 1972, small emulsified liquid silicone globules were noted on the anterior iris surface and anterior chamber angle, associated with a rise in the intraocular pressure. Medical therapy was initiated, including topical pilocarpine, epinephrine, and oral Diamox. The intraocular pressure fluctuated and rose above 50 mmHg on occasion. Laser pupilloplasty was performed on the right eye in February 1983 so that the retina could be examined. Progressive right corneal decompensation with both epithelial and stromal edema was evident. The patient, however, continued to enjoy visual acuity at the 20/200 range until 1983, 16 years after silicone placement. In March 1983, cyclocryotherapy for uncontrolled glaucoma was performed. The intraocular pressure was brought down below 30 mmHg. Band keratopathy and a pale optic nerve were noted in the right eye. In June 1985, intraocular pressure of 8 mmHg was noted in that eye and the patient had no light perception in either eye. Case 5 (late keratopathy). A 69-year-old bilateral aphakic man presented in 1961 with recurrent retinal detachment in the left eye. He had had three scleral buckling procedures in that eye previously. Revision of the buckle was performed by Cibis on two subsequent occasions. Retinal detachment of the right eye
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Fig 3. Examples of late complications include left, silicone induced glaucoma, and right, keratopathy.
occurred in September 1961, requiring a scleral buckling procedure to that eye. The retina remained reattached with good vision since that time. A recurrent total retinal detachment with advanced PVR occurred in the left eye, requiring liquid silicone implantation on September 12, 1961. The left retina was successfully reattached except for slight inferior elevation. Visual acuity was restored to 20/25 in the right eye and CF in the left. The left eye encountered no complications until seven years after silicone placement, when keratopathy was noted. Visual acuity dropped to the hand motion level in the left eye in March 197 5, 14 years after silicone placement. Visual acuity in the right eye remains at 20/25.
DISCUSSION Late complications due to intravitreal liquid silicone have been well documented in the literature. 3- 10• 19 They include cataract, glaucoma, and keratopathy (Fig 3). These complications have been noted to occur usually within one to three years after silicone placement in the majority of affected eyes. What is not known is whether they occur to a significant frequency in those eyes that have maintained functional vision and tolerated the presence ofliquid silicone on a long-term basis. Our present study clearly shows that silicone that has remained inert in eyes for a prolonged period may still bring about late complications ten or more years after its placement. Figure 2 and Table 1 illustrate that in the passage of time, functional vision is gradually lost; after ten years, only approximately 50% of eyes still maintained functional vision. Comparing those that maintained functional vision for ten or more years (group I) with those less than ten years (group II), late complications occurred later in group I than in group II. The lack of statistical significance may be a reflection of the small sample size. The location 656
of silicone behind a "protective layer" of formed vitreous appeared to be a prominent feature in group I (Fig 1) . The vitreous barrier prevented a massive migration of silicone into the anterior segment to induce late complications. Again, the small sample size may be responsible for the lack of statistical significance in the delay of late complications by the vitreous barrier. In time, all phakic eyes in group I developed cataract, while nearly 40% and 17% developed glaucoma and keratopathy, respectively. However, recurrent retinal detachment, rather than late complications, was the predominant cause of functional failure in those eyes that lost functional vision in less than ten years (group II). Nearly 40% of eyes with initial anatomical success in our series developed recurrent retinal detachment. This was the cause of functional failure in almost 80% of all eyes in group II, occurring at an average of 4.4 years after silicone placement, while affecting none in group I. This feature was found to have high statistical significance. Since silicone has a lower specific gravity than vitreous, it has a tendency to rise to the superior vitreous cavity when the patient is in the upright position. The loss of tamponade to the inferior retina may result in progressive inferior retinal detachment. Thus, some degree of inferior retinal detachment is noted in almost all silicone-filled eyes. Eventually, the central vision is affected as the inferior detachment reaches the macula (Fig 4). The subretinal fluid may shift upward temporarily detaching the macula during sleep in the supine position. This process can be expected to progress more rapidly in eyes with more advanced preretinal traction and inferior retinal breaks. With the absence of tamponade on the inferior retina by the silicone, the contracting preretinal membranes can elevate the inferior retinal breaks, allowing superior migration of inferior subretinal fluid . Continued
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liquefaction of the residual vitreous gel also makes more fluid available for the subretinal space with the passage of time. The majority of eyes in our series had silicone placement before the availability of vitrectomy instrumentation. Thus, the elimination of preretinal membranes might have been less than ideal in many of these eyes. A total silicone fill in the vitreous cavity was not considered desirable because of the possibility of forcing silicone into the anterior segment. Eyes in group II had significantly more advanced PVR and more inferior retinal breaks than those in group I; this was consistent with the predominance of recurrent detachment in those eyes. Progressive recurrent inferior retinal detachment eventually affecting the superior retina accounted for all cases of functional failure not due to late complications in our series. Some investigators have cited retinal toxicity by silicone to be responsible for delayed visual loss not due to late complications.20- 22 However, studies by LaBelle and Okun, and others have not confirmed such retinal toxicity. 23 - 27 Some have pointed to the reduction in ERG amplitudes in animal eyes implanted with liquid silicone to be proof of retinal toxicity. 22 Other studies found no comparable ERG changesY·28 More recent studies provided mounting evidence that the electrophysiological variance is due to preexisting retinal changes and the electrical insulating effect of the liquid silicone. 29 - 31 Prompt recovery of A and B waves was noted by several investigators after the removal of the silicone. 29 - 31 Thus up to this point, there is still no absolute proof of retinal toxicity due to liquid silicone. The development of cataract is the most common late complication of intraocular silicone. Leaver et al noted some degree of clinically recognizable lens changes not present prior to surgery in 49% of phakic eyes in one year, and up to 65% in three years. 19 Cataract developed in over 60% of the phakic eyes in our series. The most common type of cataract is a combination of nuclear sclerotic and posterior subcapsular opacities. Past histological analysis has demonstrated silicone vacuoles adherent to the anterior and posterior lens surfaces, but no actual silicone invasion of the lens substance, 19 We thus agree with Leaver and Grey that the lens degeneration is not due to the toxic effect of silicone, but to the presence of silicone vacuoles on the lens surface, preventing normal metabolic exchange. 19 Although cataract formation is common, it progresses gradually. The majority of the affected eyes are not functionally incapacitated for a prolonged period. Two eyes in group I did not lose visual function until I 1 and 15 years after surgery respectively. In both eyes, there was minimal contact between the silicone and the posterior lens capsule. When cataract extraction is considered, an extracapsular procedure leaving the posterior capsule intact is most appropriate. In our series, 16.8% of eyes developed glaucoma. This compares with 15% reported by Leaver and Grey. 19 Although earlier reports have shown that almost all eyes developing glaucoma were aphakic, long-term follow-up
Fig 4. Recurrent inferior retinal detachment with fibrous proliferation at the inferior edge of silicone bubble. '
studies have indicated that the presence of the lens did not prevent the development of glaucoma (36% of eyes with glaucoma in our series were phakic). In time, emulsified foamy silicone globules were able to penetrate the "protective" lens-vitreous barrier in many eyes, inducing glaucoma. One eye in group I did not develop intractable glaucoma until 17 years after surgery, requiring cyclocryotherapy (see case 4). Histological analysis in these eyes has shown the presence of silicone-laden macrophages within the trabecular meshwork, without evidence of structural damage to the collagen fibers and endothelial lining. 19 This strongly suggests obstruction as the cause of glaucoma. The fact that glaucoma in these eyes responds well to routine medical therapy supports this observation. In our series, 12.3% of eyes developed keratopathy. It is not a coincidental finding that all but one eye with keratopathy·in our series was aphakic. Silicone was noted to be in the anterior chamber in all eyes which had keratopathy. Histological study demonstrated deposition of small silicone vacuoles with surrounding macrophages on the corneal endothelium (Fig 5). 3•4•19 Electron microscopy showed membrane-bound vacuoles within the cytoplasm of some endothelial cells without evidence of disturbanCe to the Descemet's membrane or the deep stroma. 19 Not all eyes with silicone in the anterior chamber necessarily developed keratopathy. At least five eyes in group I had evidence of emulsified silicone in the anterior chamber without corneal changes. However, when large amounts of silicone enter the anterior chamber, keratopathy is the rule. When a significant amount of silicone has migrated into the anterior chamber of a phakic eye, anterior cham657
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AC
Fig 5. Histopathologic appearance of keratopathy with deposition of fine · silicone globules on endothelium. Note macrophages surrounding these globules. AC = anterior champer; S = silicone globules; C = cornea.
ber wash-out should be performed to prevent development ofkeratopathyand glaucoma. However, once silicone enters the anterior chamber of an aphakic eye, itisvirtually impossible to remove unless the entire intraocular silicone content is removed. When k~ratopathy has developed, it is essentially Irreversible. Peiu;trating keratoplasty in these · eyes is often unsuccessful. 32 Although intravitreal liquid silicone had great benefit for many monoqliar individuals (see case reports I and 2), it had little benefit for the binocular patients in our series. Through the entire series of binocular patients (54 of 103), the silicone treated eye was actively used by only one binocular patient, while being generally ignored by the rest. In our comparison between groups I and II, we noted that the silicone treated eye had relatively shortterm benefit for the majority of patients. Almost 65% of these eyes (33/51) lost functional vision in less than five years (average, 4.8 years). On the other hand, a large number of these eyes developed glaucoma, requiring therapeutic intervention ( 13 eyes or 25.5% ), while 15 eyes (29 .4%) developed cosmetically disfiguring keratopathy. Cataract was found in almost all the phakic eyes in the two groups (23 eyes or 95.2% ). If not for the fear of silicone migration into the anterior chamber, many more of these eyes with cataract would have undergone cataract extraction. Although 19 eyes were documented for enucleation in our study, many more enucleations might have been performed but not recorded due to loss of follow~up. Therefore, we believe that the relative risks outweigh the relative benefits of intravitreal liquid silicone placement in binocular patients. With few exceptions, liquid silicone should be limited to the monocular patient whose remaining eye is threatened with visual loss due to advanced retinal detachment. 658
We believe the ideal procedure for intravitrealliquid silicone placement calls for the following conditions: (I) adequate relief of preretinal traction; (2) neatly total silicone fill within the vitreous cavity; and (3) preseQce of a physical barrier between the silicone and the anterior segment. Conditions I ap.d 2 can be fulfilled by a vitrectomy and membrane peeling procedure. Condition 3 can be fulfilled by leaving formed anterior vitreous in the ca:se ofphakic eyes 18 • 19 ; leaving the anterior lens capsule intact when lensectomy and anterior vitrectomy are necessary 14; or leaving the posterior lens capsule in place when cataract extraction is necessary before or after the silicone procedure. We agree with Gonvers and others that extensive panretinal photocoagulation is helpful in these eyes; 16 lt creates strong retina.:..RPE adhesions, resisting traCtion by the residual preretinal membranes. To reduce the chance oflate complications, we further recommend the removal of the liquid silicone two to six months after its placement when the PVR process has quieted down, unless significant vitreoretinal traction remains. This can be accomplished easily with the use ofvitrectomy insrrumentation: silicone floats to the top and exits through a small scJerotomy as balanced salt solution is infused. · Recently, inferior iridectomy has been suggested by some retinal surgeons to be useful in preventing late anterior segment complications in aphakic eyes with liquid silicone. 34 It is suspected that the inferior iris opening allows aqueous to flow forward between the silicone oil and the corneal endothelium, thus preventing keratopathy and glaucoma (R. Zivojnovic, personal communicatjon). It has also been pointed out that as a result of improved manufacturing techniques, a better grade ofliquid silicone with more uniform molecular size can be produced (VP Gabel, personal communication). Whether its use will re-
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OCULAR TOLERANCE TO LIQUID SILICONE
duce the incidence of silicone emulsification and the associated late complications remains to be proven. We conclude that while liquid silicone will continue to pfay an important role in vitreoretinal surgery, its induction of late complications must not be ignored. Much work still lies ahead to improve its therapeutic effectiveness and to reduce its harmful effects.
13. Machemer R. Synopsis of Vail; third vitreous seminar March 8 to 15, 1980 in Vail, Colorado, USA. lnt Ophthalmol1980; 2:175-7. 14. Deutman AF, Eijkenboorn GJM, Fanuriakis C. A microsurgical method for the injection of intraocular silicone oil. lnt Ophthalmol1980; 2:63-9. 15. Scott JD. Use of liquid silicone in vitrectomised eyes. Dev Ophthalmol . 1981; 2:185-90. 16. Gonvers M. Temporary use of intraocular silicone oil in the treatment of detachment with massive periretinal proliferation; preliminary report. Ophthalmologica 1982; 184:210-8. 17. Constable I, Mohamed S, Tan PL. Super viscous silicone liquid in retinal surgery. Aust J Ophthalmol 1982; 10:5-11 . 18. Grey RHB, Leaver PK. Silicone oil in the treatment of massive preretinal retraction. I. Results in 105 eyes. Br J Ophthalmol1979; 63:355-60. 19. Leaver PK, Grey RHB, Garner A. Silicone oil injection in the treatment of massive preretinal retraction. II. Late complications in 93 eyes. Br J Ophthalmol1979; 63:361-7. 20. Lee PF, Donovan RH, Mukai N, et al. Intravitreous injection of silicone: an experimental study. I. Clinical picture and histology of the eye. Ann Ophthalmol1969; 1(2):15-25. 21. Mukai N, Lee PF, Schepens CL. Intravitreous injection of silicone: an experimental study. II. Histochemistry and electron microscopy. Ann Ophthalmol1972; 4:273-87. 22. Mukai N, Lee PF, Oguri M, Schepens CL. A long-term evaluation of silicone retinopathy in monkeys. Can J Ophthalmol 1975; 10:391402. 23. Labelle P, Okun E. Ocular tolerance to liquid silicone; an experimental study. Can J Ophthalmol 1972; 7:199-204. 24. Stone W Jr. Alloplasty in surgery of the eye. N Engl J Med 1958; 258: 486-90. 25. Armaly MF. Ocular tolerance to silicones. I. Replacement of aqueous and vitreous by silicone fluids. Arch Ophthalmol1962; 68:390-5. 26. Levine AM, Ellis RA. Intraocular liquid silicone implants. Am J Ophthalmol 1963; 55:939-43. 27. Meredith TA, Lindsey DT, Edelhauser HF, Goldman AI. Electroretinographic studies following vitrectomy and intraocular silicone oil injection. Br J Ophthalmol 1985; 69:254-60. 28. Ober RR, Blanks JC, Ogden TE, et al. Experimental retinal tolerance to liquid silicone. Retina 1983; 3:77-84. 29. Momirov D, van Lith GHM, Zivojnovic R. Electroretinogram and electrooculogram of eyes with intravitreously injected silicone oil. Ophthalmologica 1983; 186:183-8. 30. Frumar KD, Gregor ZJ, Carter RM, Arden GB. Electrophysiological responses after vitrectomy and intraocular tamponade. Trans Ophthalmol Soc UK 1985; 104:129-132. 31. Foerster MH, Esser J, Laqua H. Silicone oil and its influence on electrophysiologic findings. Am J Ophthalmol 1985; 99:201-6. 32. Beekhuis WH, van Rij G, Zivojnovic R. Silicone oil keratopathy: indications for keratoplasty. Br J Ophthalmol1985; 69:247-53.
ACKNOWLEDGMENTS The authors acknowledge the assistance of Steve Mandel, BA, and Mae Gordon, PhD, for the statistical analyses; also Jeanne Toma and Sue Hamilton for preparation of the manuscript.
REFERENCES 1. Cibis PA, Becker B, Okun E, Canaan S. The use of liquid silicone in retinal detachment surgery. Arch Ophthalmol1962; 68:590-9. 2. Cibis PA. Vitreous transfer and silicone injections. Trans Am Acad Ophthalmol Otolaryngol1964; 68:983-97. 3. Okun E. lntravitreal surgery utilizing liquid silicone; a long term followup. Trans Pac Coast Oto-Ophthalmol Soc 1968; 49:141-59. 4. Okun E, Arribas NP. Therapy of retinal detachment complicated by massive preretinal fibroplasia (iong-term follow-up of patients treated with intral(itrealliquid silicone). In: Symposium on Retina and Retinal Surgery; Transactions of the New Orleans Academy of Ophthalmology. StLouis: CV Mosby, 1969; 278-93. 5. Watzke RC. Silicone retinopoiesis for retinal detachment; a long-term clinical evaluation. Arch Ophthalmol1967; 77:18!)-96. 6. Cockerham WD, Schepens CL, Freeman HM. Silicone injection in retinal detachment. Arch Ophthalmol1970; 83:704-12. 7. Kanski JJ, Daniel R. lntravitreal silicone injection in retinal detachment. Br J Ophthalmol1973; 57:542-5. 8. Alexandridis E, Daniel H. Results of silicone oil injection into the vitreous. Dev Ophthalmol 1981; 2:24-7. 9. Leaver Pk, Grey RHB, Ga,rner A. Complications following silicone-oil injection. Mod Probl Ophthalmol1979; 20:290-4. 10. Haut J, Ullern M, Chermet M, Van Effenterre G. Complications of intraocular injections of silicone combined with vitrectomy. Ophthalmologica 1980; 180:29-35. 11. Okun E. The current status of silicone oil (analysis of long-term successes). In: Irvine AR, O'Mi3,1ley C. Advances in Vitreous Surgery. Springfield: Chiirles C Thomas, 1976; 518-22. 12. Machemer R. Massive periretinal proliferation: a logical approach to therapy. Trans Am Ophthalmol Soc 1977; 75:556-86.
Discussion
by Dwain G. Fuller, MD Although Cjbis introduced the use of liquid silicone for the treatment of complicated retinal detachments in 1961, most American retinal surgeons abandoned its use within a few years due to a low long-term reattachment rate, less than spectacular
From Texas Retina Associates, Dallas.
visual results in anatomically successful cases, and many early and delayed postoperative complications attributed to silicone. Pars plana vitrectomy techniques with removal of preretinal membranes and the use of intraocular inert gas, pioneered by Machemer in the eary 1970s, improved the reattachment rate in proliferative vitreoretinopathy (PVR), but significantly more than half of all cases were still failures. Parke and Aaberg dem~ onstrated in 1984 that endolaser photocoagulation and planned
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retinotomies in conjunction with pars plana vitrectomy could improve surgical success in PVR. Various pharmacologic agents have also been used intravitreally and paraocularly in conjunction with pars plana vitrectomy in an attempt to inhibit proliferation of periretinal membranes, but their use has not dramatically improved the surgical success rate in PVR. 1•2 Encouraging reports regarding the use of intraocular liquid silicone from Scott and other European retinal surgeons during the last few years have rekindled l1 new interest in the United States in the use of intraocular silicone for the treatment of PVR. These two papers contrast the original non-vitrectomy use of silicone oil as developed by Cibis with the newer approach of using silicone oil as an intraocular tamponade in conjunction with modern vitreous surgery. Chan and Okun present valuable and unique data regarding the long-term effects of silicone in 407 eyes, some ofwhich have been followed for over 20 years. It is important to realize, however, that virtually all ofthe eyes in the authors' series had silicone injection without pars plana vitrectomy and with only minimal vitreous cavity and preretinal membrane sectioning. Despite these limitations, a number of eyes fared reasonably well for many years and provided ambulatory vision for monocular patients. Close appraisal of the authors' data reveals that only 25% of all operated eyes achieved count fingers vision or better at any time following surgery. Within ten years following surgery, eyes with count fingers vision or better had fallen to only 12% of all operated eyes with adequate follow-up. Late complications were common and included the well-known four: cataract formation, corneal clouding, glaucoma, and recurrent retinal detachment. Eyes that were initial successes and which maintained functional vision for ten years or longer were, almost without exception, eyes that had less severe PVR and fewer inferior retinal breaks. Chan and Okun conclude their paper with the suggestion that intraocular silicone be reserved primarily for use in monocular patients whose only eye has an advanced stage of retinal detachment. Cox et al report anatomic and visual results in 51 consecutive PVR eyes treated with silicone after previous failure with stateof-the-art pars plana vitrectomy techniques including membrane stripping and sectioning, air-fluid reattachment, gas tamponade, endolaser, and the occasional use of retinal tacks, retinotomies, and retinal sutures. The authors achieved a final retinal reattachment rate of 65%, but a significant number of the eyes required more than one operation. Fifty-four percent of all eyes achieved count fingers vision or better following surgery, and among the anatomically successful cases, 74% of eyes returned to count fingers vision or better. Twenty nine percent of the anatomically successful cases had significant visual improvement to the level of 20/200 or better. The surgical results of Cox et al are definitely encouraging, but these authors also noted corneal decompensation, glaucoma, cataract formation, and retinal redetachment as relatively common postoperative complications. In hopes of reducing the incidence oflate postoperative problems, the authors removed the silicone from 10 of 33 anatomically successful cases and noted a 30% redetachment rate.
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Historically, most intraocular silicone has been placed with the intent to leave it in the eye as a permanent retinal tamponade. In 1985, Gonvers presented a large series of PVR eyes treated with vitrectomy techniques in conjunction with the use of silicone oil as a temporary retinal tamponade for only four to six weeks. 3 His reattachment rate with a visual acuity of at least count fingers vision six months after silicone removal was 62%. He noted a very low complication rate with this short-term use of silicone tamponade with the exception of frequent cataract formation in phakic eyes, a problem that was easily managed with conventional cataract surgery. Visual results were encouraging with 99% of the successful cases returning at 3/200 or better vision and 17% of the eyes achieving 20/100 or better vision. Gonvers believes that extensive photocoagulation at the time of silicone surgery and in the early postoperative period permits silicone removal at four to six weeks with a relatively low redetachment rate. His technique of temporary silicone tamponade may permit early enough removal of silicone to avoid most long-term complications. Based on the available scientific data, it is logical to suggest the use of intraocular liquid silicone for eyes with PVR which have failed with aggressive vitrectomy techniques including scleral buckling, endolaser, and intraocular inert gas. Since approximately 10% of patients with a retinal detachment in one eye will develop a retinal detachment in the fellow eye, I would not aqvocate limiting the use of silicone to monocular patients. 4 The ultimate solution to the vexing problem ofPVR still eludes us, but the judicious use of intraocular silicone can permit salvage of vision in a significant number of eyes otherwise doomed to blindness. Chan and Okun are to be congratulated for their PliPer which gives not only interesting historical insight into the origin of the use of intraocu~ar silicone in the treatment of complicated retinal detachments, but also gives invaluable long-term follow-up of such cases. ·Cox et al are also to be commended for their presentation which demonstrates that the use of intraocular silicone in conjunction with skillful pars plana vitrectomy techniques can provide retinal reattachment in approximately two-thirds of eyes with proliferative vitreoretinopathy. References 1. Tano Y, Chandler D, Machemer R. Treatment of intraocular proliferation with intravitreal injection of triamcinolone acetonide. Am JOphthalmol 1980; 90:810-6. 2. Blumenkranz M, Hernandez E, Ophir A, Norton EWD. 5-fluorouracil: new applications in complicated retinal detachment for an established antimetabolite. Ophthalmology 1984; 91:122-9. 3. Gonvers M. Temporary silicone oil tamponade in the management of retinal detachment with proliferative vitreoretinopathy. Am JOphthalmol 1985; 100:239-45. 4. Davis MD, Segal PP, MacCormick A The natural course followed by the fellow eye in patients with rhegmatogenous retinal detachment. In: Pruett RC, Regan CDJ, eds. Retina Congress; 25th Anniversary Meeting of the Retina Service, Massachusetts Eye and Ear Infirmary. New York: Appleton-Century-Crofts, 1972; 643-60.