Capsule contraction after continuous curvilinear capsulorhexis: Poly(methyl methacrylate) versus silicone intraocular lenses

Purpose: To evaluate the progressive contraction of the anterior capsule opening after in the-bag implantation of 2 types of intraocular lenses (IOLs). Setting: Department of Ophthalmology, University of Brest, Brest, France. Methods: in this prospective study, 32 single-piece poly(methyl methacrylate) (PMMA) (Pharmacia 812 C) and 30 3-piece silicone IOLs with PMMA haptics (Allergan SI-40NB) were implanted in the bag after standardized phacoemulsification performed by the same surgeon. Aii patients were older than 70 years, and none had zonular weakness. The surface of continuous curvilinear capsulorhexis (CCC) was measured 1, 30, and 150 days postoperatively using a 3 charge-coupled device camera and a digitized computer analysis system, Results: A significant progressive constriction was observed at 150 days in 70% in the silicone group and 32% in the PMMA group. In addition, CCC contraction was greater in silicone group (P < .05). The mean surface decrease was 4.20 mm(2) in the silicone group and 1.53 mm(2) in the PMMA group. There was no correlation between sex, age, initial capsulorhexis area, and final capsule shrinkage. In some eyes, especially in those with a single-piece PMMA IOL (41 %), there was no constriction, but fine changes in the capsule opening were seen. Conclusion: Evolutive anterior capsulorhexis modifications were observed in all patients; however, the contraction rate was statistically higher in the silicone group. These results suggest that silicone IOL implantation should be avoided in eyes at risk for CCC constriction. (C) 1999 ASCRS and ESCRS.