Mathematical model to predict the need for neodymium:YAG capsulotomy based on posterior capsule opacification rate

PURPOSE: To evaluate a model to project the estimated time required before patients having primary phacoemulsification require neodymium:YAG (Nd:YAG) laser capsulotomy. SETTING: Eleven private practices in the United States. METHODS: Projections of time to capsulotomy were based on assessment of the early development of posterior capsule opacification (PCO) over time. The PCO data were collected during a clinical study to evaluate MDX-RA, an investigational immunotoxin designed to limit epithelial cell growth, preventing postsurgical PCO. From the PCO data, the estimated time to Nd:YAG capsulotomy in a placebo-treated group was compared with the actual time to capsulotomy in a cohort of patients from general practice who had had phacoemulsification. RESULTS: By 6 months, the mean Opacification Index in the MDX-RA group was significantly lower than that in the placebo group (P < .05) and it remained significantly lower at 12 (P < .001), 18 (P < .001), and 24 (P < .016) months. The rate of PCO in the MDX-RA group was approximately 6 times lower than that in the placebo group (P < .0004). Fifty-seven percent in the placebo group and 4% in the MDX-RA group were projected to require an Nd:YAG capsulotomy within 3 years of primary cataract surgery. Projected values for the placebo group were similar to actual values observed in the population-based cohort. CONCLUSIONS: This technique could be used to predict the need for Nd:YAG capsulotomy using early measurements of PCO.