Josef M. Schmidbauer

Evaluation of neodymium:yttrium-aluminum-garnet capsulotomies in eyes implanted with AcrySof intraocular lenses

PURPOSE As of December 31, 2000, the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy rate for the Alcon AcrySof intraocular lens (IOL) as measured in our database was 3.3%. This was the lowest of any IOL model used in the United States. Only 12 of 361 cases required treatment. We analyzed possible surgical reasons that may have been responsible for the posterior capsule opacification (PCO) in this small group. Special attention was given to the three surgical factors that we had previously identified as being important for PCO reduction: (1) quality of cortical clean up, (2) type of haptic fixation, and (3) continuous curvilinear capsulorhexis (CCC) size and shape. DESIGN Comparative autopsy tissue analysis. PARTICIPANTS Three hundred sixty-one human eyes obtained postmortem with Alcon AcrySof IOLs, accessioned between January 1995 and December 2000 from Lions Eye Banks. METHODS The eyes were evaluated by the Miyake-Apple posterior photographic technique. MAIN OUTCOME MEASURES The area and intensity of Soemmerings ring and type of fixation were studied in 361 eyes. The size and shape of the CCC and relation of the CCC edge to the IOLs optic rim were analyzed in 168 eyes. RESULTS The amount of Soemmerings ring formation was significantly larger in the group of IOLs requiring Nd:YAG capsulotomy (Nd:YAG group). The not in-the-bag fixated IOLs required more Nd:YAG capsulotomies. Although the trend was clear, the number of specimens was not large enough to acquire statistical significance. The Nd:YAG group showed a highly significant difference compared with the No Nd:YAG group with regard to the amount of clock hours of the CCC edge on the optic rims surface (P < 0.001). Mean CCC diameters were significantly larger in the Nd:YAG group (P < 0.05). CONCLUSIONS The amount of Soemmerings ring correlates with the quality of cortical clean up. Cells within the Soemmerings ring are the direct precursors of PCO. This study confirms our previous laboratory studies and the clinical assumption that the incidence of PCO and thus the need for Nd:YAG capsulotomy is correlated with the cortical clean up. A second clinical assumption, that poor IOL fixation increases the risk of PCO, is also strongly suggested in this study. This study also verifies the relation of the CCC to PCO and the Nd:YAG laser, namely that a relatively small CCC without tears is best to prevent this complication. Use of a high-quality IOL combined with diligent attention to these three surgical factors should lower further the incidence of PCO.

Epithelial downgrowth after clear cornea phacoemulsification: Report of two cases and review of the literature

OBJECTIVE To report two cases of diffuse epithelial downgrowth after clear cornea phacoemulsification and to review the different treatment options for this ominous disease. DESIGN Two interventional case reports. METHODS Retrospective review of two eyes from two different patients in whom epithelial downgrowth developed 7 and 3 months after uneventful clear cornea phacoemulsification. In the first case, the epithelial invasion seemed to be growing from the temporal incision site onto the corneal endothelium toward the visual axis. Cryotherapy was applied to the affected cornea, with control of the growing membrane. A penetrating keratoplasty was performed to restore visual function. In the second patient, the membrane was attached to the iris and posterior cornea and was confirmed by diagnostic argon laser photocoagulation. This case was surgically treated with en bloc excision and a corneoscleral graft. MAIN OUTCOME MEASURES Visual acuity at the final follow-up visit. RESULTS Surgical treatment of the epithelial downgrowth was different for both patients. In the postoperative period, a best-corrected visual acuity of 20/60 and 20/30 was achieved in each case. No regrowth of the membrane was observed. CONCLUSIONS Treatment of epithelial downgrowth is controversial. We present two cases of epithelialization of the anterior chamber with either clinical or histologic confirmation after clear cornea sutureless phacoemulsification. Surgical treatment should be attempted promptly to obtain a good visual prognosis.

Snowflake degeneration of polymethyl methacrylate posterior chamber intraocular lens optic material: A newly described clinical condition caused by unexpected late opacification of polymethyl methacrylate

OBJECTIVE To report 25 cases of gradual, but sometimes progressive, late-postoperative degeneration of polymethyl methacrylate (PMMA) optics of posterior chamber (PC) intraocular lens (IOL) implants, often resulting in a clinically significant visual decrease long after the implantation, sometimes to a severity that required IOL explantation/exchange. DESIGN Analysis of explanted PC IOLs, clinical histories, and photographs. PARTICIPANTS We analyzed 25 case histories/photographs and/or explants from 18 patients implanted in the 1980s to mid-1990s with three-piece PC IOLs with PMMA optics and with polypropylene or PMMA haptics. The IOL optic from each case had characteristic snowflake or crystalline opacifications. This condition occurred with more than one manufacturer and in some cases was restricted to certain lot numbers. METHODS The explanted IOLs (n = 10) were studied by gross inspection and by light and scanning electron microscopy, as well as confocal and energy dispersive spectroscopy. MAIN OUTCOME MEASURES The snowflake lesions were noted within the IOL optics. The nature of these lesions was investigated. RESULTS Assimilation of clinical information with pathologic and morphologic profiles of all cases suggested that the snowflake opacification was a small spherical lesion surrounded by an outer pseudocapsule composed of compressed, degenerated PMMA, with a central core containing convoluted fragments of PMMA. The lesions were classified into four clinical and pathologic grades according to their density and severity. CONCLUSIONS This is the first clinicopathologic correlative report on this complication. We postulate that manufacturing variations in some IOL models fabricated in the 1980s and early 1990s are responsible. The snowflake lesions seem to represent a destruction of the PMMA material. The cluster of lesions in implanted lenses manufactured by Surgidev was less progressive than some other models, including lenses made by IOPTEX Research Corporation. This identification of a condition previously unreported is important to alert clinicians regarding these perplexing lesions that may otherwise be considered idiopathic, with no obvious clinical hint as to their origin. The prevalence noted thus far is still too low to in any way suggest that this condition would occur in 100% of PMMA IOLs from these manufacturers. However, these late-occurring lesions, present in lens models that were implanted in hundreds of thousands of patients in the last decade or so, could have constituted a true epidemic, except that many of the patients are now deceased.

Effect of haptic angulation on posterior capsule opacification in modern foldable lenses with a square, truncated optic edge

Purpose: To analyze the effect of different haptic angulations on posterior capsule opacification (PCO) in a modern foldable intraocular lens (IOL) with a square‐edged optic designed to reduce the incidence of PCO. Setting: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. Methods: Ten Dutch Belted, serum Pasteurella‐free pigmented rabbits of the same age and sex had bilateral phacoemulsification with endocapsular IOL implantation. The eyes were implanted with Centerflex® IOLs (Rayner) with haptic angulations of 0 degree (n = 8), 5 degrees (n = 4), 10 degrees (n = 4), or 15 degrees (n = 4). Results: There was no statistical difference in central PCO, peripheral PCO, and measured IOL decentration among the angulation groups. Conclusion: With the Centerflex IOL, haptic angulation did not seem to be a significant factor influencing PCO. It appears that the barrier effect of the IOLs truncated, square‐edged optic overrides the angulation factor in preventing PCO.

Evaluation of 3 modern single-piece foldable intraocular lenses Clinicopathological study of posterior capsule opacification in a rabbit model

Purpose: To assess the development of posterior capsule opacification (PCO) with 3 modern single‐piece foldable intraocular lenses (IOLs) in a histopathological study and to compare the potential preventive effects of the IOL design and biomaterial in retarding PCO. Setting: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. Methods: Thirty‐one rabbit eyes were randomly operated on with phacoemulsification and implantation of 3 single‐piece foldable lenses: a hydrophilic acrylic design, the Rayner Centerflex® 570H (n = 11); a hydrophobic acrylic design, the Alcon AcrySof® SA30AL (n = 10); and a silicone large‐hole plate design, the Staar AA‐4203VF (n = 10). Central PCO (CPCO), peripheral PCO (PPCO), and Soemmerings ring formation were evaluated 3 weeks after surgery using the Miyake−Apple posterior photographic technique. Histological sections of each globe were prepared to document capsular bag status and performance of IOL geometry. Results: The acrylic IOLs (Centerflex and AcrySof) had lower CPCO and PPCO scores than the silicone plate IOL (P < .05). There was no significant difference in Soemmerings ring formation among the 3 models. Pathological evaluations revealed effective blockage of migrating lens epithelial cells (LECs) at the site of the truncated optic edge of the Centerflex and AcrySof IOLs, even in the presence of large amounts of retained/regenerative cortical material. Conclusions: The AcrySof IOL has a hydrophobic surface and the Centerflex a hydrophilic surface, but no correlation to these characteristics could be identified. The single‐piece AcrySof optic geometry created a clear‐cut barrier effect equal to that of its 3‐piece predecessor. The anatomic profile of the Centerflex IOL shows the same characteristics. The optics of both acrylic lenses have square truncated edges that functionally block ingrowth of migrating LECs toward the central visual axis, leaving clear posterior capsules. The square optic edge was an appropriate geometric configuration to create a barrier effect. There was no effect of the biomaterial on PCO prevention.

Posterior capsule opacification.

Posterior capsule opacification (PCO, secondary cataract) has been well-known since extracapsular techniques (extracapsular cataract extraction [ECCE]) were introduced into cataract surgery (Fig 1). Indeed, PCO was noted by Ridley in his first intraocular lens (IOL) implantations. PCO usually causes impairment of visual acuity by direct blockage of the visual axis. Also, indirect complications secondary to mechanical forces resulting from cell proliferation may occur (e.g., striae or folds of the posterior capsule, traction-induced IOL decentration). Clinically, visual symptoms may vary widely, though they usually are proportionate to the amount of PCO. Nonetheless, many patients who have relatively severe PCO, as documented by slit-lamp examination, have few or no complaints; these patients therefore do not require treatment. Other patients may complain vigorously about even minimal haze, requiring secondary capsulotomy. As we enter the new millennium, it is worthwhile to recognize that the incidence of PCO is decreasing rapidly. PCO was the most common remaining complication of ECCE (including phacoemulsification) and posterior chamber intraocular lens (PCIOL) implantation. It occurred at an incidence of between 30% and 50% through the 1980s and early 1990s,

Pharmacologic prevention of posterior capsule opacification: in vitro effects of preservative-free lidocaine 1% on lens epithelial cells.

Purpose: To assess the in vitro effectiveness of preservative‐free lidocaine 1% in removing lens epithelial cells (LECs) from the anterior capsule and to evaluate the effect of lidocaine on the LECs. Setting: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. Methods: Eight rabbits (16 eyes) were used in the study. After the rabbits were killed, the eyes were enucleated and divided into 2 groups. In Group 1 (n = 8 eyes), LECs were exposed to preservative‐free lidocaine 1% or balanced salt solution (BSS®) for 1, 2, or 5 minutes. The anterior capsules were then stained with trypan blue and alizarin red. Photomicrographs of each capsule were taken and analyzed for LEC damage. In Group 2 (n = 8 eyes), hydrodissection was performed with 1 of the agents, followed by phacoemulsification and cortical cleanup. The LEC attachment to the anterior capsule was evaluated by histopathology. Results: Anterior capsule fragments irrigated with BSS showed no LEC nuclear staining; ie, no direct toxic effect. In those irrigated with preservative‐free lidocaine 1%, the LECs showed mild toxicity; some cells showed blue nuclear staining. After hydrodissection with lidocaine, the capsules were almost free of LECs; after hydrodissection with BSS, the capsules showed a normal layer of LECs attached to the anterior capsule. Conclusions: Preservative‐free lidocaine 1% may help diminish the amount of live LECs by facilitating cortical cleanup, by loosening the desmosomal area of cell−cell adhesion with decreased cellular adherence, or by a direct toxic effect. The use of this agent may help prevent posterior capsule opacification.

Influence of fibronectin on the adherence of Staphylococcus epidermidis to coated and uncoated intraocular lenses

PURPOSE: To determine the effect of the modification of intraocular lens (IOL) surface properties on the adhesion of Staphylococcus epidermidis caused by fibronectin (FN) as the predominant proadhesive glycoprotein of the eyes initial foreign body reaction. SETTING: University of Saarland, Homburg/Saar, Germany. METHODS: Eleven IOL types were tested. The IOLs were of poly(methyl methacrylate), acrylate, or silicone. Some were surface modified with heparin or polysaccharide coating. The IOLs, unadsorbed or preadsorbed with fibronectin (FN), were incubated with [3H]‐thymidine‐labeled S epidermidis Rp62a, and the amount of adherent microorganisms was determined. RESULTS: Attachment of S epidermidis adhesion to various types of IOLs, both unadsorbed and FN precoated, varied significantly. The attachment to highly adhesive IOLs was almost 4‐fold greater than that to low‐adhesive IOLs. Attachment to FN precoated IOLs was generally enhanced compared with attachment to unadsorbed IOLs. Heparin surface modification resulted in no or a modest reduction in bacterial adhesion compared with unmodified IOLs. Bacterial adhesion was highly statistically significantly less on IOLs with polysaccharide surface modification. CONCLUSIONS: There was significant variability in S epidermidis adhesion to IOLs as a function of design, material, surface modification, and FN preadsorption. Application of the findings may foster new developments to further reduce the major complication in cataract surgery, infective endophthalmitis.

Overview of modern foldable intraocular lenses and clinically relevant anatomy and histology of the crystalline lens

The magnitude of the cataract problem has been clearly defined in international and federal studies. As of 1984, 12 to 15 million people worldwide were recorded as being blind from cataracts. By the late 1990s, this number had increased to an estimated 20 million, which could double early in the twenty-first century. Cataract is the most prevalent ophthalmic disease in terms of sheer numbers and, according to the United Nations Population Division, the cataract backlog will continue to increase rapidly during the next five decades as the median age of the population increases. Since the late 1960s, the number of cataract extractions per year has been steadily increasing, especially since the introduction of the intraocular lens (IOL). Although extensive research regarding the pathogenesis of cataracts is ongoing and a pharmacological preventive treatment for this blinding disease is being sought, the solution still appears to be many years away. Therefore, surgical treatment for cataracts, which increasingly includes IOL implantation, remains the only viable alternative.

Scanning electron microscopic and histologic evaluation of the AcrySof SA30AL acrylic intraocular lens. Manufacturing quality and morphology in the capsular bag

Purpose: To evaluate the properties of the AcrySof® SA30AL (Alcon Laboratories, Inc.) single‐piece foldable posterior chamber intraocular lens (IOL). Setting: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. Methods: Two nonimplanted clinical‐quality AcrySof IOLs were examined by gross, light, and scanning electron microscopy (SEM). In addition, 2 eyes implanted with this IOL obtained post‐mortem, the first such eyes accessioned in our laboratory and the first described to date, were examined using the Miyake‐Apple posterior photographic technique and by histologic sections. Results: Scanning electron microscopy of the SA30AL IOL showed excellent surface finish. The edge of the optic was square (truncated) and had a matte (velvet or ground‐glass) appearance, a feature that may minimize edge glare and other visual phenomena. A well‐fabricated square or truncated optic edge was demonstrated. Miyake‐Apple analysis revealed that the SA30AL IOL showed appropriate fit and configuration within the capsular bag. Histologic correlation of the IOLs square edge and its relation to the capsular bag and adjacent Soemmerings ring were noted. Conclusions: The AcrySof SA30AL IOL is a well‐fabricated lens that situates well in the capsular bag. The truncated optic and its relationship to adjacent structures show a morphological profile that has been shown to be highly efficacious in reducing the rate of posterior capsule opacification.