Hitoshi Nishihara

Surface scattering in implanted hydrophobic intraocular lenses

Purpose: To describe surface scattering, a new phenomenon in polyacrylic intraocular lenses (IOLs), and discuss the possible cause of this finding. Setting: Showa University, Fujigaoka Hospital, Yokohama, Kanagawa, Japan. Methods: This observational case series involved 40 patients who received the AcrySof® IOL (Alcon Laboratories, Inc.) as part of a clinical trial in 1991. Four patients (5 eyes) were evaluated. Thirty‐three patients had the same surgery in 1999, and the findings in these patients were compared with those in the earlier patients. Lens surface scattering was evaluated by area densitometry using Scheimpflug photography. No statistical analysis was done because of the small sample size. Results: The 5 IOLs implanted in 1991 showed various degrees of surface scattering. The degree of scattering was greater than that in the 1999 group. There was no degradation in visual performance and no manifestation of intraocular inflammation or other adverse effect from the IOLs in either group. Attempts to remove foreign material on the IOL using the neodymium:YAG (Nd:YAG) laser were unsuccessful. Conclusions: The surface scattering did not appear to be due to deposition of foreign material on the IOL surface. Densitometry and the results of Nd:YAG laser treatment suggest that the changes occurred in the near‐surface layer. Phase separation of water near the IOL surface in the inherently hydrophobic material may explain the phenomenon. Newer AcrySof IOLs appear to have less surface scattering.

Capsular stabilization device to preserve lens capsule integrity during phacoemulsification with a weak zonule

&NA; We describe a new capsular stabilization device for suspending a lens with weak zonular support. It is flexible, 10.0 mm in length, and fashioned from 5‐0 nylon. The contact portion is bent at 1.25 mm with an end bifurcating to form a T‐shape to minimize stress on the capsular equator. After a continuous curvilinear capsulorhexis is created, the capsular stabilization devices to hook the capsulotomy margin are inserted. The T‐shaped end is passed around the anterior capsular flap to fit the curvature of the equator. Phacoemulsification and aspiration using this device was performed in 12 eyes of 9 patients, and the usefulness and complications were analyzed. The capsular stabilization devices suspended the capsule and facilitated safe phacoemulsification in all eyes. Posterior capsule rupture occurred in 2 eyes. None of the cases had notable postoperative complications. This device ensures a stable capsule‐iris complex and reduces surgical risks.

Light scatter on the surface of AcrySof intraocular lenses: part I. Analysis of lenses retrieved from pseudophakic postmortem human eyes.

BACKGROUND AND OBJECTIVE To investigate the cause of light scatter measured on the surface of AcrySof intraocular lenses (Alcon Laboratories, Inc., Fort Worth, TX) retrieved from pseudophakic postmortem human eyes. MATERIALS AND METHODS Ten intraocular lenses (Alcon AcrySofModel MA60BM) were retrieved postmortem and analyzed for light scatter before and after removal of surface-bound biofilms. RESULTS Six of the 10 lenses exhibited light scatter that was clearly above baseline levels. In these 6 lenses, both peak and average pixel density were reduced by approximately 80% after surface cleaning. CONCLUSION The current study demonstrates that a coating deposited in vivo on the lens surface is responsible for the light scatter observed when incident light is applied.

Light scattering observed on the surface of acrylic intraocular lenses ten years after implantation

PURPOSE To report the long-term status of acrylic intra-ocular lenses. CASES We describe two cases of increased light scattering on the surface of acrylic intraocular lenses ten years after implantation. The scattering was non-symptomatic and visual acuity was normal. Biomicroscopy and a Scheimpflug photography system showed that the scattering apparently derived from the anterior surface of the lens, but no deposit or membranous structure was observed on the lens surface. CONCLUSION Surface scattering from acrylic intra-ocular lenses is a new finding in long-term observations. A possible etiology may be structural changes of the internal polymer.

Effect of ophthalmic solution components on acrylic intraocular lenses

PURPOSE: To investigate the effect of ophthalmic solution components on the surface of acrylic intraocular lenses (IOLs). SETTING: Department of Opthalmology, Showa University School of Medicine. METHODS: Measurement of the contact angles of ophthalmic solutions on 3 acrylic IOLs was performed. The solutions were diclofenac sodium (Diclod), bromfenac sodium (Bronuck), betamethasone phosphate (Rinderon), dibekacin sulfate (Panimycin), polysorbate 80 (Tween 20), benzalkonium chloride, chlorobutanol, methylparahydroxybenzoate, and propylparahydroxybenzoate. The IOLs were incubated at 35°C for 2 weeks in undiluted ophthalmic solutions and in 1:10 dilutions of ophthalmic solution components. The IOLs were sectioned and observed by scanning electron microscopy. RESULTS: The contact angle of Diclod and Bronuck solutions was the smallest. The contact angle of Rinderon and Panimycin was similar to that of distilled water. Scanning electron microscopy examination of IOLs incubated in ophthalmic solution components showed intralenticular changes. The IOLs immersed in ophthalmic solutions did not show any change, even after extended incubation. CONCLUSION: The chemical components of ophthalmic solutions, such as surfactants and solvents, permeate acrylic IOLs, suggesting the potential for long‐term adverse effects of eyedrops in pseudophakic eyes.