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Evaluation of 50 silicone posterior chamber lens implantations
Evaluation of 50 silicone posterior chamber lens implantations Christian Skorpik, M.D. Hans Dieter Gnad, M.D. Rupert Menapace, M.D. Markus Grasl, M.D. Wolfgang Scheidel, M.D. Vienna, Austria
ABSTRACT This study presents our experience with 50 silicone intraocular lens (IOL) implants (STAAR Surgical Company, model AA-4004) in the posterior chamber. In the relatively short-term mean postoperative follow-up of seven months, the following complications were observed: iris chafing - pigmentary dispersion, 15 (30%); IOL tilt and decentration, 7 (14%); pseudophakodonesis, 6 (12%); fibrinous exudate, 3 (6%); luxation of one haptic in the anterior chamber, I (2%); IOL tears, 5 (10%). Visual acuity of 20/20 to 20/40 was obtained in 40 patients (80%). Although no severe consequences wel'e noted, the long-term effects of the complications are unpredictable at present. Key Words: ciliary sulcus fixation, decentration, in-the-bag placement, intraocular lens, pigmentary dispersion, silicone compressible lens implant
When extracapsular cataract extraction (ECCE) is performed by phacoemulsification and a hard polymethylmethacrylate (PMMA) intraocular lens (IOL) is to be implanted, the incision must be extended. To avoid the disadvantage of enlarging the phacoemulsification incision, IOLs that can be inserted through a small opening have been developed. These "small incision lenses" are either expansible, the hydrogel lenses,I,2 or elastic, the silicone lenses. 3 ,4,5 In April 1986, we began implanting model AA-4004 silicone lenses manufactured by STAAR Surgical Company. In this paper, we report our experience with the material, the surgical technique, and the results. SUBJECTS AND METHODS Between April and December 1986, we implanted STAAR AA-4004 silicone posterior chamber lenses in 50 patients. Twenty-two patients were male, 28 were female; the mean age was 70 years. Two lenses were placed in the capsular bag, 48 in the ciliary sulcus.
Eighteen lenses were implanted following planned ECCE; 32 were placed using the STAAR elastic lens injector following phacoemulsification. Pre-existing ocular pathology (in addition to cataracts) was diagnosed in ten eyes (Table 1). Table 1. Final visual acuity with posterior chamber STAAR silicone lenses. Corrected Acuity
Number of Eyes
20/20 - 20/40
40 (80%)
Preexisting Ocular Pathology Reflected in Reduced Acuity
20/60
1 (2%)
Diabetic background retinopathy
20/60
1 (2%)
Corneal scars due to keratitis eccematosa
20/200
1 (2%)
Vascular optic nerve atrophy
20/80 - 3/60
7 (14%)
Senile maculopathy
Total
50 (100%)
From the First University Eye Clinic, Vienna, Austria. Presented in part at the Symposium on Cataract, IOL and Refractive Surgery, Orlando , April 1987. Reprint requests to Christian Skorpik, M.D., Erste Universitats-Augenklinik, Spitalgasse 2, A-1090 Vienna, Austria. 640
J CATARACT REFRACT SURG- VOL
13, NOVEMBER 1987
The STAAR AA-4004 silicone IOL has a 6.0 mm diameter optic, with a total diameter of 11.5 mm. The thickness depends on the refractive power. The haptic is 0.08 mm thick, with 0.30 mm edges. Optic and haptic are one piece (Figure 1).
Fig. 2.
Fig. 1.
(Skorpik) STAAR silicone lens model AA-4004.
All operations were performed under comparable conditions, under local anesthesia, using the operating microscope. If the silicone lens was to be implanted in the ciliary sulcus, the capsulotomy opening was made almost as large as the pupil diameter to reduce the risk of opacification from direct contact of the anterior and posterior capsules. With phacoemulsification (Cavitron 9000 system), the incision was extended to approximately 4 mm after the lens cortex had been removed. In the first 27 cases, we made a corneoscleral opening; in the last five cases, a scleral pocket incision. Using a McPherson forceps, the IOL was introduced into the STAAR elastic lens injector. As a lubricant, we used IAL® (sodium hyaluronate 1% by Fidia) because it is less viscous than Healon® and has been satisfactory in our experience. The space between the iris and the anterior capsule was reformed with Healon® (or IAL), the lens injector inserted, and the IOL implanted directly in the ciliary sulcus (Figure 2). If one haptic was positioned anterior to the iris, it was possible to position it under the iris by pressing an instrument on the lens optic in the direction of the capsule. The implant was inserted in the 6 o'clock to 12 o'clock position. The viscoelastic material was removed by irrigation with acetylcholine, and the wound was closed with one to three interrupted lO-O nylon sutures. Postoperatively, we administered short-acting mydriatic agents for one week and topical corticosteroids and indomethacin eye drops (Betnesol-N-gtt and Indopto I) for six to eight weeks. In cases with corneoscleral
(Skorpik) Lens being implanted with the STAAR elastic lens injector directly into the posterior chamber.
incisions, the sutures were cut with a needle at the slitlamp approximately four weeks postoperatively in order to correct astigmatic conditions. RESULTS Mean postoperative follow-up was seven months. Excluding ten eyes with preexisting ocular pathology that reduced postoperative visual acuity (Table 1), 40 eyes (80%) obtained good visual acuity (Table 1). No cystoid macular edema has been noted and no capsulotomy has been required. Table 2 lists the postoperative complications. Table 2. Complication in 50 silicone-lens-implanted eyes. Complications
Incidence (%)
IOL tilt
4 (8)
Luxated haptic in anterior chamber
1 (2)
Decentration
3 (6)
Pseudophakodonesis
6 (12)*
Iris chafing-pigmentary dispersion
15 (30)t
Tears in IOL
5 (1O):j:
Fibrinous exudate
3 (6)§
*In all cases complicated by pigmentary dispersion tOne eye with 30 mm Hg lOP :j:Five other implants had tears that required removal §One eye had a sterile hypopyon
In five cases, movement of the implant in the STAAR injector was blocked so the compressed haptic facing the plunger tore at the optic-haptic junction and the IOL had to be explanted after the incision was extended. In two of these eyes, a silicone lens was again implanted using a forceps; the other three eyes re-
J CATARACT REFRACT SURG- VOL
13, NOVEMBER 1987
641
ceived PMMA IOLs and were not included in this study. The lens injector technique is problematic because one part of the haptic is always compressed. In five instances we observed minimal tears in the compressed haptic at the optic-haptic junction after uncomplicated insertion. The IOLs remained implanted in all five eyes and caused no postoperative complications. Insertion was facilitated and the haptic not damaged when we adopted the Faulkner implantation forceps after the first 50 cases. Four to eight days postoperatively, a fibrinous exudate was noted in two eyes; a sterile hypopyon was noted in a third patient. Within a few days, the symptoms were reversed by systemic and topical cortisone and prophylactic antibiotic therapy. The reason for these irritative reactions remains unknown. The subsequent course was uneventful. One lens implanted in the bag and two lenses implanted in the sulcus are slightly tilted and the hap tics are pressing against the iris periphery. In the eye with in-the-bag implantation, shrinkage of the bag may be the cause. One of the two eyes with sulcus fixation has developed a fibrinous reaction with possible capsule-iris adhesions; in the second eye, the corneal diameter (white to white horizontally) measures not quite 11.0 mm, which may indicate too small a ciliary sulcus diameter. One IOL showed marked decentration with a sunset phenomenon and pseudophakodonesis; the corneal diameter in this eye is 12.5 mm. This implant changed from a vertical to a horizontal position. In addition, increased pigmentary dispersion was observed in this eye (Figure 3). Mydriasis reinforced pigmentary dis-
persion, and the intraocular pressure rose at times to 30 mm Hg. The intraocular pressure is now normal without any treatment. Five lenses, implanted in eyes with corneal diameters more than 12.0 mm, also showed pseudophakodonesis complicated by pigmentary dispersion. There have been no consequences of these findings. Two of these five lenses are decentered. In one eye, we observed lens decentration caused by progressive iridocapsular synechia formation. One part of the haptic luxated into the anterior chamber and settled in the iridocorneal angle. The optic is tilted, but centered. Since the eye is free of irritation and the vision is not impaired (Figure 4), we have not taken any remedial measures.
Fig. 4.
(Skorpik) One haptic luxated into the anterior chamber because of progressive synechial formation between capsule and iris pigment epithelium.
In 15 (30%) of the 50 eyes, increased pigmentary dispersion was observed. Six of these eyes showed pseudophakodonesis. Seventeen patients (34%), operated on for bilateral cataracts, were already pseudophakic with a PMMA lens implanted in the fellow eye. In eight (47%) of these patients, marked pigmentary dispersion was observed in the silicone-implanted eyes; none of the 17 eyes with PM MA implants showed this reaction. Postoperative intraocular pressure has not differed between the silicone-implanted eyes and the PMMA-implanted eyes. However, because the PMMA lenses have an angled haptic and are implanted in the capsular bag routinely, the two groups are not directly comparable.
Fig. 3.
642
(Skorpik) Decentered lens with pseudophakodonesis caused by large ciliary sulcus diameter.
DISCUSSION Although anatomic as well as visual results in the 50 eyes are satisfactory, a critical evaluation of particular aspects is required. One aspect is the haptic design of silicone IOLs; another, the appropriateness of ciliary-
J CATARACT REFRACT SURG- VOL
13, NOVEMBER 1987
sulcus or in-the-bag placement. We have also noted a high incidence of complications during a relatively short-term follow-up (Table 2). Presently, these complications have not produced significant untoward effects and have not impaired the functional visual outcome in any way. Nevertheless, we will have to observe these eyes very carefully in the future. Histopathologic investigations in human eyes have shown that the silicone haptics do not cause significant inflammatory reactions in the adjacent uveal tissue and that the haptics do not erode into the iris or the ciliary body.6 In a primate model, the relatively inert nature of silicone with only mild inflammatory tissue reactions was shown. 7 A study in rabbits also demonstrated that silicone was less traumatic to intraocular tissues than was PMMA, and that silicone IOLs showed minimal adhesion to intraocular structures. 8 Because of this nonadhesive quality, the silicone implant remains unstable unless it is accurately fixated in the sulcus. Resulting pseudophakodonesis may cause irritation and pigmentary dispersion with secondary glaucoma. 9 These complications can only be prevented by designing silicone IOLs with flexible loop haptics, comparable to those of standard PMMA implants, which could adjust to the sulcus size. If the lens is too small, the haptics bend toward the zonular fibers or the ciliary border of the iris. If the lens is too large, lens decentration, pseudophakodonesis, and the windshieldwiper phenomenon occur, as observed in our patient group. Post-mortem measurements of eyes indicated a sulcus diameter from 10.0 mm to 11.8 mm, with a mean of 1l.0 mm (Ocular Surgery News, September 1, 1984, pp 8, 10). Milauskas (Ocular Surgery News, August 15, 1986, pp 64-65) attempted to minimize the problem by recommending that silicone IOLs be used only in eyes with a corneal diameter ofless than 12.5 mm. We have, however, encountered the problems in patients with a corneal diameter of more than 12.0 mm. It is not clear why the corneal diameter should necessarily correlate with the ciliary sulcus diameter. The latter remains an undetermined variable. Since pigmentary dispersion is related to ciliary sulcus fixation, we recommend that silicone lenses be implanted in the capsular bag. Lens models for in-thebag placement should, however, have rather rigid haptics to provide stability and prevent IOL tilting. Polymethylmethacrylate IOLs may cause pigmentary dispersion and secondary glaucoma by chafing the iris pigment epithelium. 10,11 Popham et al. 12 consider one of the advantages of the elastic silicone IOL to be that it causes less iris chafing and pigmentary dispersion. We do not agree with their opinion of sulcus placement. We observed pigmentary dispersion in 30% of the eyes, and in all eyes with pseudophakodonesis. The lens movements damaged the pigment epithelium. When implanted in the ciliary sulcus, the silicone lens is
positioned closer to the posterior surface of the iris; because of the refractive index, the silicone optic is thicker than that ofPMMA lenses; silicone hap tics are not angled so the optic is positioned closer to the iris. All of these cause more intense lens-iris contact and occasional pigmentary dispersion. Based on our limited experience, these complications can be avoided only by in-the-bag implantation and an improved, appropriate design of the silicone haptics. In conclusion, the results of our initial experience are satisfactory but not perfect. The high rate of complications is remarkable, and we have to be cautious about shifting from a well-known lens materials with very good results, such as PMMA, to a material with which there is less experience and that has a proportionately greater number of complications in the short term. Presently, the only advantage of silicone implants is phacoemulsification with small incision implantation. But the size of the wound opening should not be the only reason for using a possibly inferior lens material. Future investigations will have to evaluate the long-term effect of siliconelens-related complications and will have to demonstrate differences, advantages, and disadvantages of the various lens materials. REFERENCES 1. Packard RBS, Garner A, Arnott EJ: Poly-HEMA as a material for intraocular lens implantation: A preliminary report. Br ] OphthalmoI65:585-587, 1981 2. Yalon M, Blumenthal M, Goldberg EP: Preliminary study of hydrophilic hydrogel intraocular lens implants in cats. Am Intra-Ocular Implant Soc] 10:315-317, 1984 3. Mazzocco TR: Progress report: Silicone IOLs. Cataract 1(4):18-19, 1984 4. Faulkner GD: Early experience with STAAR ™ silicone elastic lens implants. ] Cataract Refract Surg 12:36-39, 1986 5. Chen TT: Clinical experience with soft intraocular lens implantation. ] Cataract Refract Surg 13:50-53, 1987 6. Crawford JB, Faulkner GO: Pathology report on the foldable silicone posterior chamber lens. ] Cataract Refract Surg 12:297-300, 1986 7. Fogle JA, Blaydes JE, Fritz KJ, Blaydes SH, et al: Clinicopathologic observations of a silicone posterior chamber lens in a primate model. ] Cataract Refract Surg 12:281-284, 1986 8. Cook CS, Peiffer RL Jr, Mazzocco TR: Clinical and pathologic evaluation of a flexible silicone posterior chamber lens design in a rabbit model. ] Cataract Refract Surg 12:130-134, 1986 9. Newman DA, McIntyre OJ, Apple OJ, Popham JK, et al: Pathologic findings of an explanted silicone intraocular lens. ] Cataract Refract Surg 12:292-297 , 1986 10. Huber C: The gray iris syndrome; an iatrogenic form of pigmentary glaucoma. Arch Ophthalmol 102:397-398, 1984 11. Smith JP: Pigmentary open-angle glaucoma secondary to posterior chamber intraocular lens implantation and erosion of the iris pigment epithelium. Am Intra-Ocular Implant Soc] 11:174-176, 1985 12. Popham JK, Apple OJ, Newman OA, Isenberg RA, et al: Advantages and limitations of soft intraocular lenses: A scientific perspective . In : Mazzocco TR , Rajacich GM , Epstein E , eds, Soft Implant Lenses in Cataract Surgery, Thorofare , NJ, Slack, Inc, 1986, pp 11-30
J CATARACT REFRACT SURG- VOL
13, NOVEMBER 1987
643
ABSTRACT This study presents our experience with 50 silicone intraocular lens (IOL) implants (STAAR Surgical Company, model AA-4004) in the posterior chamber. In the relatively short-term mean postoperative follow-up of seven months, the following complications were observed: iris chafing - pigmentary dispersion, 15 (30%); IOL tilt and decentration, 7 (14%); pseudophakodonesis, 6 (12%); fibrinous exudate, 3 (6%); luxation of one haptic in the anterior chamber, I (2%); IOL tears, 5 (10%). Visual acuity of 20/20 to 20/40 was obtained in 40 patients (80%). Although no severe consequences wel'e noted, the long-term effects of the complications are unpredictable at present. Key Words: ciliary sulcus fixation, decentration, in-the-bag placement, intraocular lens, pigmentary dispersion, silicone compressible lens implant
When extracapsular cataract extraction (ECCE) is performed by phacoemulsification and a hard polymethylmethacrylate (PMMA) intraocular lens (IOL) is to be implanted, the incision must be extended. To avoid the disadvantage of enlarging the phacoemulsification incision, IOLs that can be inserted through a small opening have been developed. These "small incision lenses" are either expansible, the hydrogel lenses,I,2 or elastic, the silicone lenses. 3 ,4,5 In April 1986, we began implanting model AA-4004 silicone lenses manufactured by STAAR Surgical Company. In this paper, we report our experience with the material, the surgical technique, and the results. SUBJECTS AND METHODS Between April and December 1986, we implanted STAAR AA-4004 silicone posterior chamber lenses in 50 patients. Twenty-two patients were male, 28 were female; the mean age was 70 years. Two lenses were placed in the capsular bag, 48 in the ciliary sulcus.
Eighteen lenses were implanted following planned ECCE; 32 were placed using the STAAR elastic lens injector following phacoemulsification. Pre-existing ocular pathology (in addition to cataracts) was diagnosed in ten eyes (Table 1). Table 1. Final visual acuity with posterior chamber STAAR silicone lenses. Corrected Acuity
Number of Eyes
20/20 - 20/40
40 (80%)
Preexisting Ocular Pathology Reflected in Reduced Acuity
20/60
1 (2%)
Diabetic background retinopathy
20/60
1 (2%)
Corneal scars due to keratitis eccematosa
20/200
1 (2%)
Vascular optic nerve atrophy
20/80 - 3/60
7 (14%)
Senile maculopathy
Total
50 (100%)
From the First University Eye Clinic, Vienna, Austria. Presented in part at the Symposium on Cataract, IOL and Refractive Surgery, Orlando , April 1987. Reprint requests to Christian Skorpik, M.D., Erste Universitats-Augenklinik, Spitalgasse 2, A-1090 Vienna, Austria. 640
J CATARACT REFRACT SURG- VOL
13, NOVEMBER 1987
The STAAR AA-4004 silicone IOL has a 6.0 mm diameter optic, with a total diameter of 11.5 mm. The thickness depends on the refractive power. The haptic is 0.08 mm thick, with 0.30 mm edges. Optic and haptic are one piece (Figure 1).
Fig. 2.
Fig. 1.
(Skorpik) STAAR silicone lens model AA-4004.
All operations were performed under comparable conditions, under local anesthesia, using the operating microscope. If the silicone lens was to be implanted in the ciliary sulcus, the capsulotomy opening was made almost as large as the pupil diameter to reduce the risk of opacification from direct contact of the anterior and posterior capsules. With phacoemulsification (Cavitron 9000 system), the incision was extended to approximately 4 mm after the lens cortex had been removed. In the first 27 cases, we made a corneoscleral opening; in the last five cases, a scleral pocket incision. Using a McPherson forceps, the IOL was introduced into the STAAR elastic lens injector. As a lubricant, we used IAL® (sodium hyaluronate 1% by Fidia) because it is less viscous than Healon® and has been satisfactory in our experience. The space between the iris and the anterior capsule was reformed with Healon® (or IAL), the lens injector inserted, and the IOL implanted directly in the ciliary sulcus (Figure 2). If one haptic was positioned anterior to the iris, it was possible to position it under the iris by pressing an instrument on the lens optic in the direction of the capsule. The implant was inserted in the 6 o'clock to 12 o'clock position. The viscoelastic material was removed by irrigation with acetylcholine, and the wound was closed with one to three interrupted lO-O nylon sutures. Postoperatively, we administered short-acting mydriatic agents for one week and topical corticosteroids and indomethacin eye drops (Betnesol-N-gtt and Indopto I) for six to eight weeks. In cases with corneoscleral
(Skorpik) Lens being implanted with the STAAR elastic lens injector directly into the posterior chamber.
incisions, the sutures were cut with a needle at the slitlamp approximately four weeks postoperatively in order to correct astigmatic conditions. RESULTS Mean postoperative follow-up was seven months. Excluding ten eyes with preexisting ocular pathology that reduced postoperative visual acuity (Table 1), 40 eyes (80%) obtained good visual acuity (Table 1). No cystoid macular edema has been noted and no capsulotomy has been required. Table 2 lists the postoperative complications. Table 2. Complication in 50 silicone-lens-implanted eyes. Complications
Incidence (%)
IOL tilt
4 (8)
Luxated haptic in anterior chamber
1 (2)
Decentration
3 (6)
Pseudophakodonesis
6 (12)*
Iris chafing-pigmentary dispersion
15 (30)t
Tears in IOL
5 (1O):j:
Fibrinous exudate
3 (6)§
*In all cases complicated by pigmentary dispersion tOne eye with 30 mm Hg lOP :j:Five other implants had tears that required removal §One eye had a sterile hypopyon
In five cases, movement of the implant in the STAAR injector was blocked so the compressed haptic facing the plunger tore at the optic-haptic junction and the IOL had to be explanted after the incision was extended. In two of these eyes, a silicone lens was again implanted using a forceps; the other three eyes re-
J CATARACT REFRACT SURG- VOL
13, NOVEMBER 1987
641
ceived PMMA IOLs and were not included in this study. The lens injector technique is problematic because one part of the haptic is always compressed. In five instances we observed minimal tears in the compressed haptic at the optic-haptic junction after uncomplicated insertion. The IOLs remained implanted in all five eyes and caused no postoperative complications. Insertion was facilitated and the haptic not damaged when we adopted the Faulkner implantation forceps after the first 50 cases. Four to eight days postoperatively, a fibrinous exudate was noted in two eyes; a sterile hypopyon was noted in a third patient. Within a few days, the symptoms were reversed by systemic and topical cortisone and prophylactic antibiotic therapy. The reason for these irritative reactions remains unknown. The subsequent course was uneventful. One lens implanted in the bag and two lenses implanted in the sulcus are slightly tilted and the hap tics are pressing against the iris periphery. In the eye with in-the-bag implantation, shrinkage of the bag may be the cause. One of the two eyes with sulcus fixation has developed a fibrinous reaction with possible capsule-iris adhesions; in the second eye, the corneal diameter (white to white horizontally) measures not quite 11.0 mm, which may indicate too small a ciliary sulcus diameter. One IOL showed marked decentration with a sunset phenomenon and pseudophakodonesis; the corneal diameter in this eye is 12.5 mm. This implant changed from a vertical to a horizontal position. In addition, increased pigmentary dispersion was observed in this eye (Figure 3). Mydriasis reinforced pigmentary dis-
persion, and the intraocular pressure rose at times to 30 mm Hg. The intraocular pressure is now normal without any treatment. Five lenses, implanted in eyes with corneal diameters more than 12.0 mm, also showed pseudophakodonesis complicated by pigmentary dispersion. There have been no consequences of these findings. Two of these five lenses are decentered. In one eye, we observed lens decentration caused by progressive iridocapsular synechia formation. One part of the haptic luxated into the anterior chamber and settled in the iridocorneal angle. The optic is tilted, but centered. Since the eye is free of irritation and the vision is not impaired (Figure 4), we have not taken any remedial measures.
Fig. 4.
(Skorpik) One haptic luxated into the anterior chamber because of progressive synechial formation between capsule and iris pigment epithelium.
In 15 (30%) of the 50 eyes, increased pigmentary dispersion was observed. Six of these eyes showed pseudophakodonesis. Seventeen patients (34%), operated on for bilateral cataracts, were already pseudophakic with a PMMA lens implanted in the fellow eye. In eight (47%) of these patients, marked pigmentary dispersion was observed in the silicone-implanted eyes; none of the 17 eyes with PM MA implants showed this reaction. Postoperative intraocular pressure has not differed between the silicone-implanted eyes and the PMMA-implanted eyes. However, because the PMMA lenses have an angled haptic and are implanted in the capsular bag routinely, the two groups are not directly comparable.
Fig. 3.
642
(Skorpik) Decentered lens with pseudophakodonesis caused by large ciliary sulcus diameter.
DISCUSSION Although anatomic as well as visual results in the 50 eyes are satisfactory, a critical evaluation of particular aspects is required. One aspect is the haptic design of silicone IOLs; another, the appropriateness of ciliary-
J CATARACT REFRACT SURG- VOL
13, NOVEMBER 1987
sulcus or in-the-bag placement. We have also noted a high incidence of complications during a relatively short-term follow-up (Table 2). Presently, these complications have not produced significant untoward effects and have not impaired the functional visual outcome in any way. Nevertheless, we will have to observe these eyes very carefully in the future. Histopathologic investigations in human eyes have shown that the silicone haptics do not cause significant inflammatory reactions in the adjacent uveal tissue and that the haptics do not erode into the iris or the ciliary body.6 In a primate model, the relatively inert nature of silicone with only mild inflammatory tissue reactions was shown. 7 A study in rabbits also demonstrated that silicone was less traumatic to intraocular tissues than was PMMA, and that silicone IOLs showed minimal adhesion to intraocular structures. 8 Because of this nonadhesive quality, the silicone implant remains unstable unless it is accurately fixated in the sulcus. Resulting pseudophakodonesis may cause irritation and pigmentary dispersion with secondary glaucoma. 9 These complications can only be prevented by designing silicone IOLs with flexible loop haptics, comparable to those of standard PMMA implants, which could adjust to the sulcus size. If the lens is too small, the haptics bend toward the zonular fibers or the ciliary border of the iris. If the lens is too large, lens decentration, pseudophakodonesis, and the windshieldwiper phenomenon occur, as observed in our patient group. Post-mortem measurements of eyes indicated a sulcus diameter from 10.0 mm to 11.8 mm, with a mean of 1l.0 mm (Ocular Surgery News, September 1, 1984, pp 8, 10). Milauskas (Ocular Surgery News, August 15, 1986, pp 64-65) attempted to minimize the problem by recommending that silicone IOLs be used only in eyes with a corneal diameter ofless than 12.5 mm. We have, however, encountered the problems in patients with a corneal diameter of more than 12.0 mm. It is not clear why the corneal diameter should necessarily correlate with the ciliary sulcus diameter. The latter remains an undetermined variable. Since pigmentary dispersion is related to ciliary sulcus fixation, we recommend that silicone lenses be implanted in the capsular bag. Lens models for in-thebag placement should, however, have rather rigid haptics to provide stability and prevent IOL tilting. Polymethylmethacrylate IOLs may cause pigmentary dispersion and secondary glaucoma by chafing the iris pigment epithelium. 10,11 Popham et al. 12 consider one of the advantages of the elastic silicone IOL to be that it causes less iris chafing and pigmentary dispersion. We do not agree with their opinion of sulcus placement. We observed pigmentary dispersion in 30% of the eyes, and in all eyes with pseudophakodonesis. The lens movements damaged the pigment epithelium. When implanted in the ciliary sulcus, the silicone lens is
positioned closer to the posterior surface of the iris; because of the refractive index, the silicone optic is thicker than that ofPMMA lenses; silicone hap tics are not angled so the optic is positioned closer to the iris. All of these cause more intense lens-iris contact and occasional pigmentary dispersion. Based on our limited experience, these complications can be avoided only by in-the-bag implantation and an improved, appropriate design of the silicone haptics. In conclusion, the results of our initial experience are satisfactory but not perfect. The high rate of complications is remarkable, and we have to be cautious about shifting from a well-known lens materials with very good results, such as PMMA, to a material with which there is less experience and that has a proportionately greater number of complications in the short term. Presently, the only advantage of silicone implants is phacoemulsification with small incision implantation. But the size of the wound opening should not be the only reason for using a possibly inferior lens material. Future investigations will have to evaluate the long-term effect of siliconelens-related complications and will have to demonstrate differences, advantages, and disadvantages of the various lens materials. REFERENCES 1. Packard RBS, Garner A, Arnott EJ: Poly-HEMA as a material for intraocular lens implantation: A preliminary report. Br ] OphthalmoI65:585-587, 1981 2. Yalon M, Blumenthal M, Goldberg EP: Preliminary study of hydrophilic hydrogel intraocular lens implants in cats. Am Intra-Ocular Implant Soc] 10:315-317, 1984 3. Mazzocco TR: Progress report: Silicone IOLs. Cataract 1(4):18-19, 1984 4. Faulkner GD: Early experience with STAAR ™ silicone elastic lens implants. ] Cataract Refract Surg 12:36-39, 1986 5. Chen TT: Clinical experience with soft intraocular lens implantation. ] Cataract Refract Surg 13:50-53, 1987 6. Crawford JB, Faulkner GO: Pathology report on the foldable silicone posterior chamber lens. ] Cataract Refract Surg 12:297-300, 1986 7. Fogle JA, Blaydes JE, Fritz KJ, Blaydes SH, et al: Clinicopathologic observations of a silicone posterior chamber lens in a primate model. ] Cataract Refract Surg 12:281-284, 1986 8. Cook CS, Peiffer RL Jr, Mazzocco TR: Clinical and pathologic evaluation of a flexible silicone posterior chamber lens design in a rabbit model. ] Cataract Refract Surg 12:130-134, 1986 9. Newman DA, McIntyre OJ, Apple OJ, Popham JK, et al: Pathologic findings of an explanted silicone intraocular lens. ] Cataract Refract Surg 12:292-297 , 1986 10. Huber C: The gray iris syndrome; an iatrogenic form of pigmentary glaucoma. Arch Ophthalmol 102:397-398, 1984 11. Smith JP: Pigmentary open-angle glaucoma secondary to posterior chamber intraocular lens implantation and erosion of the iris pigment epithelium. Am Intra-Ocular Implant Soc] 11:174-176, 1985 12. Popham JK, Apple OJ, Newman OA, Isenberg RA, et al: Advantages and limitations of soft intraocular lenses: A scientific perspective . In : Mazzocco TR , Rajacich GM , Epstein E , eds, Soft Implant Lenses in Cataract Surgery, Thorofare , NJ, Slack, Inc, 1986, pp 11-30
J CATARACT REFRACT SURG- VOL
13, NOVEMBER 1987
643