A MODEL OF THE INCIDENCE AND CONSEQUENCES OF CHOROIDAL NEOVASCULARIZATION SECONDARY TO AGE-RELATED MACULAR DEGENERATION - COMPARATIVE EFFECTS OF CURRENT TREATMENT AND POTENTIAL PROPHYLAXIS ON VISUAL OUTCOMES IN HIGH-RISK PATIENTS

Objective: To describe the comparative impact of current and preventiv e treatments on incidence of choroidal neovascularization (CNV) and se vere vision loss in patients with bilateral soft drusen (BSD). Design: Stochastic model. Setting: US population. Patients: Prevalence cohort of white patients 43 years or older with BSD. Interventions: Applicat ion of prophylaxis of 10% to 50% efficacy to 1 or both eyes of patient s with BSD, application of laser photocoagulation to eligible CNV lesi ons, or both. Main Outcome Measures: Proportion of patients with BSD a fter 10 years with unilateral and bilateral CNV and resultant unilater al and bilateral vision loss to visual acuity of 20/200 or worse. Resu lts: The natural history of patients with BSD generated by the model s hows that 12.40% of these patients develop either unilateral or bilate ral CNV within 10 years of their entry into the BSD prevalence cohort. Bilateral disease occurs in 3.86% of patients with BSD within 10 year s. The proportion of patients with BSD becoming legally blind from CNV within 10 years is 2.54% if no treatment is performed. Current laser treatment for CNV decreases the proportion with legal blindness within 10 years to 2.24%. The addition of a preventive treatment of 10% effi cacy applied bilaterally to the current laser treatment regimen decrea ses the proportion with legal blindness to 1.86%; a 25% effective prev entive treatment de creases it to 1.34%. Comparatively, preventive tre atment of 10% and 25% efficacy given to the fellow eye only after the first eye has developed CNV decreases the proportion of legally blind patients at 10 years only to 2.06% and 1.77%, respectively. All outcom es vary with sex and age at entry into the BSD cohort. Conclusions: Pa tients with BSD face a 12.40% risk of developing CNV within 10 years. The addition of even a modest (10% effective) bilateral preventive tre atment to the current regimen for CNV would more than double the preve ntion of legal blindness in the BSD population relative to current las er treatment; a preventive treatment of 33% efficacy more than halves the rate of legal blindness caused by CNV. Preventive treatment given to the fellow eye only after the first develops CNV has substantially less impact.