Comparison of AC and PC Lenses After Vitreous Loss During ECCE

Objective: The standard definition of failure in cataract surgery is best corrected visual acuity of less than 20/40 at one year. The specific aim of this cooperative study was to compare the failure rate for those patients with vitreous loss in whom an PC IOL is placed to the failure rate for those in whom an AC IOL is placed after vitreous loss. Design: A total of 437 patients in 15 centers were randomized to AC or PC IOL over a 45-month period and were followed for a minimum of one year. The null hypothesis is that the rate of failure is the same in the two groups. All patients who were about to undergo cataract surgery in the participating centers and who did not meet an exclusion criterion were eligible for the study. At the time of surgery, if there was vitreous loss, and if in the opinion of the surgeon there was sufficient capsular support for a posterior chamber lens to be placed, then the patient was randomized into one of either the anterior or posterior chamber lens groups. The patients were then followed for complications (e.g., retinal detachment, cystoid macular edema, uveitis, glaucoma, hyphema) and for the primary end point of visual acuity of 20/40 or better at one postoperative year. An "Index Group" of about 500 patients without vitreous loss also were followed according to study protocol. These patients were compared to those in the PC and AC IOL groups with respect to outcome and baseline characteristics in order to assess the effect of vitreous loss on complication rates. All patients were followed at annual intervals until the termination of the study. This allowed the study to obtain long-term information with regard to visual acuity and complication rates.