AFTER-CATARACT AND OCULAR GROWTH IN NEWBORN RABBIT EYES IMPLANTED WITH A CAPSULE TENSION RING

Purpose: To examine after-cataract and eye growth in lensectomized new born rabbits implanted with capsule tension rings of different sizes. Setting: S:t Eriks Eye Hospital, Karolinska Institute, Stockholm, Swed en. Methods: Two groups of 24-day-old rabbits were used. In Group I (n = 9), lensectomy was performed in both eyes. In one randomly selected eye, an open poly(methyl methacrylate) (PMMA) capsule tension ring wi th a 7.0 mm diameter and 0.13 mm thickness was implanted in the capsul ar bag. The other eye was left aphakic. In Group 2 (n = 10), an open P MMA capsule tension ring with a 10.0 mm diameter and 0.13 mm thickness was implanted in one randomly selected eye, and the other eye was lef t aphakic. Axial length, corneal diameter, corneal thickness, and intr aocular pressure (IOP) were measured in all eyes preoperatively and 1, 2, and 3 months after surgery. The wet mass of the after-cataract was measured at 3 months. Three Group 1 eyes and four Group 2 eyes develo ped secondary glaucoma and were excluded from the study. Results: Axia l growth did not differ significantly between the eyes implanted with the 7.0 mm ring and the aphakic eyes (mean difference 0.01 mm; F-3;15 = 0.02; P > .25). Corneal diameter also did not differ (two-way analys is of variance [ANOVA]). Axial length growth was less in the eyes impl anted with the 10.0 mm ring than in the aphakic eyes (mean difference 1.05 mm; F-3;15 = 2.06; P < .25). The average decrease in corneal diam eter growth was 1.0 mm in the implanted eyes. Growth in the eyes with the 10.0 mm ring was significantly less than in the eyes with the 7.0 mm ring (P = .05, Wilcoxon rank-sum test). Corneal thickness and IOP d id not differ significantly between eyes (F-3;15 = 0.6; P > .25; two-w ay ANOVA). Amount of after-cataract did not differ significantly betwe en the aphakic eyes and the eyes implanted with the 7.0 mm ring. It wa s significantly less in the eyes with the 10.0 mm ring than in those w ith the 7.0 mm ring (Wilcoxon signed-rank test) and in the aphakic eye s (P < .025, Wilcoxon rank-sum test). Conclusion: In the young rabbit eye, a 10.0 mm capsule ring reduced the eye growth compared with both the aphakic eye and the eye implanted with a 7.0 mm ring. The 10.0 mm ring also inhibited the production of after-cataract compared with the production in the aphakic eye and the eye implanted with the 7.0 mm r ing.