Posterior Capsule Opacification

cost/benefit ratio is disproportional: the patient has to have multiple changes in his contact lens or spectacle, and he must make the trip to the physician's office. These involve both financial and convenience costs. Further, the patient's vision is continually changing, making his adjustment to aphakia more difficult. The ophthalmologist's costs are also very high: his time is taken by that patient, preventing him from seeing another patient, and he must continually explain to that patient what is going on and why the patient's vision is variable. Many believe that only fine nylon or polypropylene suture materials can be used for microsurgery. I suggest that this preconceived notion may be a mistake. In my view, the benefits of silk over nylon far exceed silk's costs. Nylon is nonreactive and very comfortable for the patient but is difficult to handle. Further, nylon is not elastic; its yield point is only 3 to 5%. Braided silk will elongate some 10 to 20%, depending on the tightness of the braid. Silk is much more uncomfortable to the patient, is much bulkier and thus not amenable to deep placement within the wound, and is much more reactive in tissue and tends to extrude. Posterior wound gape is more likely to occur because of the relative shallowness of silk's placement; this is why the wound tends to slide, resulting in against-the-rule astigmatism. However, wound gape does not automatically lead to leakage; wound leak is a function of the lack of tissue apposition, suture number and suture spacing. A wound closed with five sutures is more likely to leak than the same wound closed with nine sutures, regardless of suture material. Wounds heal from side to side and not end to end. The comfort of the patient is of primary importance in our surgery, but at what cost? I suggest that silk is not that uncomfortable to the patient if it is properly placed, because the cataract section cuts all corneal nerve fibers feeding the wound. I suggest that removal of silk at 3% to four weeks precedes the return of nerve fiber sensitivity. The foreign body sensation of a short silk knot is about as uncomfortable as a poorly fitting contact lens; the exposed, cut end of a nylon suture is more uncomfortable. The patient is uncomfortable since there is significant anterior segment trauma, but that trauma may be minimized by appropriate microsurgical technique. Finally, the silk-sutured wound is stable by eight weeks rather than 52. Silk, however, does have its distinct problems. The placement of the suture predisposes posterior wound gape and sliding of the wound with resultant againstthe-rule astigmatism. I compensate for this by making my incision round or oval as the preoperative keratometer reading (K) would suggest. Resultant astigmatism is most important. Oblique astigmatism may mitigate against binocularity. With silk the final K is definitely against-the-rule, but with 66

nylon that K is, in my experience, unpredictable. The truly elastic nonabsorbable suture does not exist. Until that suture is on the microsurgical scene we should all recognize the cost/benefit ratio of whatever suture and suturing technique we use. Silk gives stable wound fixation in eight weeks whereas nylon gives stability in 52 weeks. Which is better for you?D.L.

EPITHELIAL INGROWTH To the Editor: I have encountered three instances of epithelial ingrowth following the removal of an intraocular implant. Since I plan to publish these cases, I would very much like to know if anyone has had similar experiences. Louis

J.

Girard, M.D.

4126 Southwest Freeway, #500 Houston, TX 77027 (713) 965-0700

POSTERIOR CAPSULE OPACIFICATION To the Editor: In their paper* on management of the posterior capsule following posterior chamber lens implantation, Drs. Lindstrom and Harris express the opinion that contact between the posterior capsule and the convex posterior surface of a posterior chamber implant creates a protective barrier against epithelial pearl migration, which effectively reduces the incidence of capsular opacification caused by cortical cell proliferation. The authors add that contact between the intraocular lens and the capsule does not prevent capsule opacification caused by capsule fibrosis. 1 However, using the original Ridley lens whose thickness causes very firm contact between the posterior capsule and posterior convex lens surface, I reported a 30% discission rate. 2 Some of these discissions were done up to five years after lens implantation. Chambless' histological study shows that proliferation of the anterior subcapsular cuboidal cells can cause after-cataract3 without the frank appearance of Elschnig's pearls. I have not had the opportunity of reading Chambless' paper and wonder whether his term "fibrosis of the capsule" is a true pathological description or merely a clinical assessment. A true "fibrosis," as far as I know, would arise from cyclitic exudates or organized blood. In the early days of posterior chamber lens implantation I thought that early opacification of the pos-

AM INTRA-OCULAR IMPLANT SOC J-VOL. 7, JANUARY 1981

terior capsule was caused by opacification of a thin layer of clear lens fibers left on the capsule. Such a layer trapped between the capsule and lens is not easily absorbed. For that reason I devised a saucershaped posterior chamber implant 4 whose 6-mm lens optic is surrounded by a concave haptic with eight perforations: although the rim of the saucer rests on the posterior capsule the latter does not touch the posterior pole of the optic. Aqueous flows over the capsule and the remaining lens fibers are more easily hydrolized and absorbed . Although the refineme nts of modern-day extracapsular cataract extraction allow "polishing" of the posterior capsule, one cannot be certain that all lens fibers have been removed. For this reason I still use the above-described design , made with a soft plastic. Since 1977, 4% of these cases have required a discission. Incidentally, I described the pars plana approach for posterior capsulotomy in 19572 and have not had any problems during the 29 years that I have done this procedure. I have recently started a series of cases in which th e posterior pole of the soft lens is in contact with the "polished" posterior capsule. Hopefully, the relatively porous soft lens will "bind" to the posterior capsule and thus prevent any cellular ingrowth. Edward Epstein, M.D.

Johannesburg, South Africa

*

Lindstrom RL, Harris WS: Management of the posterior capsule following posterior chamber lens implantation. Am IntraOcular Implant Soc] 6:255, 1980

REFERE NCES 1. Chambless WS: Fibrosis of the posterior capsule with poste rior chamber intraocular lenses: a potential benefit? Presented at the Kelman Phacoemulsification meeting, Las Vegas, NV, October 1979 2. Epstein E: The Ridley implant. BrJ OphthalmoI4l:368, 1957 3. Duke-Elder S: Textbook of Ophthalmology. Henry Kempton , 1940, vol 3, p 3238 4. Epstein E: ~odified Ridley lenses. Br ] Ophthalmol 43:29, 1959

Dr. Lindstrom replies: We would like to thank Dr. Epstein for his comments concerning our paper. We are certainly honored by his kind interest and appreciate his long history of involvement with th e posterior chamber lens implant. In our clinical experience visually significant opacification of the posterior capsule has been caused by several etiologies. Fore most of these has been Elschnig pearl migration and proliferation behind the posterior chamber lens optic. It has been our clinical impression that adherence of the posterior lens optic

to the posterior capsule can provide a relative barrier to cell migration behind the intraocular lens . Other authors have also noted this barrier effect. 1 It certainly should be re-emphasized that this is only a relative barrier and we have no prospective study to prove a statistically significant reduction in capsular opacification related to this one variable. We do not feel that contact between the posterior capsule and the convex posterior surface of the posterior chamber lens reduces the other primary causes of capsular opacification , such as fibrosis, capsular wrinkling, deposition of inflammatory or pigmentary deposits, or organization of residual blood . The pathophys iology of what we describe clinically as fibrosis of the posterior capsule is most likely proliferation of cells on th e capsule surface. To my knowledge there is no confirmed histopathology report of opacification of the posterior capsule itself, which is a hyalin membrane approximately 10 microns in thickness. 2 Possible origins for fibrotic-appearing strands crossing the posterior capsule would include the anterior subcapsular e pithelium , residual cortical cells, ciliary or retinal pigment epithelial cells, inflammatory cells or blood elements. The lens implant designs mentioned by Dr. Epstein are certainly interesting and a secondary discission rate of 4% with follow-up since 1977 is quite exemplary. We look forward to hearing more about the techniques producing these results. Finally, we would like to apologize for not recognizing Dr. Epstein for his description of the pars plana approach to poste rior capsulotomy. We are certainly pleased to see that h e has been using this technique for secondary discission since 1957 without any problems. In review, I note with interest that Harold Ridlei stated of his first eight cases: "The principal complication has been thickening of the posterior capsule. It might be possible to divide this from behind but at the risk of displacing or scratching the plastic lens. Alternatively, it may in the future be found advisable to perform a capsulotomy before insertion of the lens. " Richard L. Lindstrom , M. D. Minneapolis, MN

REFERENCES 1. Simcoe CW: An ounce of prevention, in Em ery J~ (ed): Cur-

rent Concepts in Cataract Surgery. St Louis, CV ~ oshy, 1978, pp 213-231 2. Roy FH: After-cataract: clinical and pathological evaluation. Ann OphthalmoI 3:1364, 1971 3. Ridley H : Intra-ocular acrylic lenses. Trans Ophthal Soc UK 71 :617, 1951

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