Daijiro Kurosaka

Effect of intraocular lens design on posterior capsule opacification after continuous curvilinear capsulorhexis

Abstract We compared the effect of biconvex and convex‐piano (posterior piano) intraocular lenses on posterior capsule opacification (PCO) following continuous curvilinear capsulorhexis (CCC) in 212 eyes. During the three years following surgery, the cumulative frequency of neodymium:YAG laser posterior capsulotomy, calculated with the Kaplan‐Meier method, was significantly higher in patients in the biconvex group (32.5% by the third year) than in those in the convex‐piano group (5.9% by the third year) (P < .05, Wilcoxon’s test; P < .01, Cox‐Mantel’s test). Measured with the tracing method, the area within a 5 mm diameter central circle that developed Elschnig pearls was 2.93 ± 4.91 mm2 in the biconvex group and 1.66 ± 2.37 mm2 in the convex‐piano group. In the study, PCO was less severe in the convex‐piano group than in the biconvex group following CCC. These results are contrary to those reported previously in patients with can‐opener capsulotomy.

Creating cataract in a pig eye.

The purpose of this study was to create a uniform, reproducible hardened lens nucleus and an anterior capsule in a pig eye that approximate those in the human eye for use in cataract surgery training. The lens nuclei was hardened and anterior capsule elasticity was reduced in pig eyes by injecting the lens with mixtures of formalin and alcohol (ethanol, 2-propanol, or both). A 30 gauge needle was used to pierce the lens 3.0 mm from the limbus. Then, 0.2 mL of the formalin and alcohol mixture was injected. The most effective mixture was formalin, ethanol, and 2-propanol in the ratio 4:3:3. Fifteen minutes after this mixture was injected, the pig eye had nuclear cataract with grade III hardness and an anterior capsule that approximated the capsule in a human cataractous eye. The cataract created by this method will be useful in teaching continuous curvilinear capsulorhexis, divide and conquer and phaco chop phacoemulsification, and nuclear hydrodelineation and rotation.

Three year prospective, randomized evaluation of intraocular lens implantation through 3.2 and 5.5 mm incisions

Purpose: To compare the long‐term clinical results of two small incision cataract surgery procedures. Setting: Seven centers in Japan. Methods: Two hundred eyes were randomly assigned to receive a silicone intraocular lens (IOL) through a 3.2 mm incision or a poly(methyl methacrylate) (PMMA) IOL through a 5.5 mm incision. Except for incision size and implantation technique, the surgical methods were identical. Uncorrected and corrected visual acuity, keratometry, flare‐cell intensity, specular microscopy, and neodymium:YAG (Nd:YAG) laser posterior capsulotomy rate were analyzed up to 3 years after surgery. Results: Eyes in the 3.2 mm incision group had significantly better uncorrected and corrected visual acuity in the early postoperative period and lower aqueous flare intensity immediately after surgery, but these differences disappeared after the first postoperative month. However, surgically induced astigmatism was significantly less in the 3.2 mm incision group than in the 5.5 incision group throughout the study. The Nd:YAG laser capsulotomy rate was higher in the silicone IOL group (23.5% at 3 years postoperatively) than in the PMMA IOL group (18.4%), but the difference was not statistically significant. Conclusion: Smaller incision cataract surgery led to earlier recovery of visual function in the short term and less induced astigmatism in the long term.

Elschnig pearl formation along the posterior capsulotomy margin after neodymium: YAG capsulotomy

Purpose: To determine the incidence of Elschnig pearl formation along the capsulotomy margin (string of pearls) after neodymium:YAG (Nd:YAG) laser posterior capsulotomy and to elucidate its clinical features, predisposing factors, effect on visual function, and association with additional capsulotomy. Setting: Keio University Hospital, Tokyo, Japan. Methods: The records of 418 eyes that had had Nd:YAG posterior capsulotomy after cataract surgery were retrospectively reviewed. Of those, 315 were excluded for short follow‐up (fewer than 12 months) or insufficient clinical examination data. In the remaining 103 eyes, the incidence of string of pearls was calculated, and its clinical features, predisposing factors, effect on visual function, and correlation with additional capsulotomy were evaluated. Results: String of pearls was identified in 49 eyes (47.6%); 37 (75.5%) developed pearls within 1 year after Nd:YAG capsulotomy. The incidence was significantly higher in patients having intraocular lens implantation and continuous curvilinear capsulorhexis (CCC) than in those without (95.9 versus 61.1% and 97.9 versus 55.6%, respectively). No significant differences were found in patient age and sex, total Nd:YAG energy, and the presence of diabetes mellitus or high myopia. String of pearls caused visual disturbances in 17 eyes (34.7%). The rate of repeat capsulotomy was higher in patients with string of pearls than in those without (36.7 and 9.3%, respectively). Conclusions: String of pearls formation was a common and significant complication after Nd:YAG posterior capsulotomy. Intraocular lens implantation and CCC may promote its formation.

Teaching continuous curvilinear capsulorhexis using a postmortem pig eye with simulated cataract

&NA; We modified an inexpensive, easily prepared model using a postmortem pig eye for training ophthalmology residents to perform continuous curvilinear capsulorhexis. To reduce the tension and elasticity of the porcine anterior lens capsule, 0.05 mL of formalin mixed with hydroxyethylcellulose or a viscoelastic material is injected into the anterior chamber via the corneal limbus to fix the surface of the central anterior lens capsule of the pig eye in situ. One or 2 minutes after the injection, only the anterior lens capsule is fixed and corneal transparency is maintained. The reduction in tension and elasticity of the anterior lens capsule caused by its fixation increases the resemblance of the simulated cataract to the human cataract.

Clinical evaluation of a five-zone refractive multifocal intraocular lens

Purpose: To evaluate the clinical performance of a five‐zone refractive multifocal intraocular lens (AMO, model MPC‐25NB, Array®). Methods: We performed a retrospective clinical trial of 31 cataract patients (mean age 64.3 years). The parameters studied were intraoperative and postoperative complications, distance and near visual acuity, spectacle use, decreased number of corneal endothelial cells, contrast sensitivity, percentage of glare disability, near binocular vision, and depth of focus. Results: Intraoperatively, iris damage occurred in two eyes (4.2%), vitreous loss in one eye (2.1 %), and consecutive rupture of Zinn’s zonule and vitreous in one eye (2.1 %). Postoperatively, posterior capsule opacification was observed in two eyes (4.2%), temporary intraocular pressure increase in one eye (2.1 %), and cystoid macular edema in one eye (2.1%). Uncorrected distance visual acuity of 20/40 or better was achieved by 34 of 37 eyes (91.9%) with less than 1.5 diopters of preoperative keratometric astigmatism; best corrected distance acuity of 20/20 or better was achieved by 41 of 45 eyes (91.1 %). Near visual acuity with distance correction of 20/40 or better was achieved by 29 of 43 eyes (67.4%). These data were compared retrospectively with data from control patients who received monofocal lenses, and no significant differences in the decreased number of corneal endothelial cells were found. Mean contrast sensitivities were within normal range for all spatial frequencies. Percentage of glare disability and near binocular vision were within normal limits. Conclusions: Eyes implanted with the five‐zone refractive multifocal lens showed better near visual acuity than control eyes and compared favorably in other aspects of visual function, indicating that these lenses are effective and safe.

Lens epithelial cell proliferation onto the intraocular lens optic in vitro

Purpose: To determine how lens epithelial cells (LECs) proliferate onto an intraocular lens (IOL) after extracapsular cataract surgery. Setting: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan. Methods: We cultured the capsular bags retaining LECs of eight human eye‐bank eyes and six rabbit eyes that had had extracapsular lens extraction with in‐the‐bag implantation of a poly(methyl methacrylate) (PMMA) IOL and a PMMA ring. Cell proliferation onto the IOL optic was monitored by a time‐lapse video system. Results: Cells proliferated onto the IOL optic via the anterior capsulotomy margin, the inner surface of the anterior capsule, and the posterior capsule. They formed cell sheets similar to the membranes observed in clinical cases. Conclusions: Since the cells proliferated from the anterior capsule as well as from the posterior capsule onto the IOL optic, the membranes observed clinically on the IOL optic may be LEC sheets.

Fibrous membrane formation at the capsular margin in capsule contraction syndrome.

PURPOSE To determine whether the pathogenesis of capsule contraction syndrome involves the outgrowth of the fibrous membrane from the anterior capsule margin. SETTING Department of Ophthalmology, Keio University School of Medicine, Tokyo, and the Ando Eye Clinic, Kanagawa, Japan. METHODS A retrospective review of medical records and slitlamp photographs was conducted in 12 eyes (10 patients) that had required treatment for a narrowed anterior capsule opening after cataract surgery. All patients had had continuous curvilinear capsulorhexis and phacoemulsification with implantation of an intraocular lens in the capsular bag. Specimens of surgically removed fibrous membrane were examined by histopathological methods. RESULTS Fibrous membrane on the inner surface of the anterior capsule and the linear folds of the anterior capsule were present in each eye. In 10 eyes of 8 patients, the fibrous membrane was on the outer surface of the anterior capsule and covered the capsular folds at its margin. Pathological study showed that this fibrous membrane consisted of the flattened lens epithelial cells that proliferated on the inner and outer surfaces of the shrunken anterior capsule. The outgrowth of this membrane from the margin of the anterior capsule to the center of the opening of the anterior capsule was noted. CONCLUSION In this study, capsule contraction syndrome involved contraction of the fibrous membrane as well as its outgrowth from the capsule margin.

Inhibition of Lens Epithelial Cell Migration by an Acrylic Intraocular Lens in vitro

We developed a new in vitro system to evaluate the effect of intraocular lenses (IOLs) on the migration of lens epithelial cells (LECs) and determined how acrylic and other IOLs influence LEC migration using this model. In an in vitro system, porcine LECs were cultured in a cell culture chamber insert, containing a collagen membrane, for 10 days with no IOL or with various types of IOLs. Migration of LECs beneath each IOL optic was observed with an inverted-phase microscope. The cell-free areas under the IOL optic, where the LECs had not migrated, were measured. Without IOL, LECs completely covered the collagen membrane within 5 days after plating (5.0 ± 0.0 days). Complete coverage was slowed by a silicone IOL (6.7 ± 1.2 days, p = 0.0305). LECs cultured with acrylic or with round- or sharp-edged polymethylmethacrylate (PMMA) IOLs did not completely cover the area. Ten days after initiating cultures, the cell-free areas under IOLs with sharp edges (acrylic, 41.1 ± 8.0%; sharp-edged PMMA, 60.9 ± 39.0%) were significantly larger than under IOLs with round edges (silicone, 0.0 ± 0.0%; round-edged PMMA, 1.5 ± 1.2%). A sharp edge may act as a barrier to LEC migration. Moreover, LEC migration under the acrylic IOL slowed after the LECs had crossed the barrier of the optic edge, perhaps due to acrylic adhesive properties. Only a few LECs reached the collagen membrane beneath the central 3 mm of the acrylic IOL. This new in vitro model was useful in evaluating the effect of various IOLs on LEC migration. Acrylic IOLs inhibited LEC migration by not only a sharp edge but also other factors, such as adhesive properties.

TGF-β2 increases α-smooth muscle actin expression in bovine retinal pigment epithelial cells

Purpose. To examine whether transforming growth factor-β2 (TGF-β2) induces the expression of α-smooth muscle actin (SMA), a biochemical marker of myofibroblasts, in cultured bovine retinal pigment epithelial (RPE) cells.Methods. Bovine RPE cells were cultured in F-12 nutrient mixture supplemented with 5% fetal bovine serum (FBS), with or without TGF-β2 (0.01–10 ng/ml) for 6 days. During this culture period, cells did not reach a confluence. Alpha-SMA was detected immunocytochemically with a mouse monoclonal antibody, and the ratio of the number of α-SMA positive cells to the total number of cells was calculated.Results. About 10% of the cells in control cultures with only FBS were positive for α-SMA. TGF-β2 increased the ratio of positive cells dose-dependently (p < 0.0001), while a neutralizing antibody against TGF-β2 blocked this effect.Conclusions. TGF-β2 induced expression of α-SMA in bovine RPE cells.