Choroidal neovascularization prevention trial

Abstract

Severe visual loss in age related macular degeneration (ARMD) may be due to choroidal neovascularization (90%) or to geographic atrophy (10%). Drusen are the common precursor for the development of either of these forms of ARMD. Eyes with large drusen (also called soft drusen) have thickening of the basement membrane of the retinal pigment epithelium which predisposes to the development of choroidal neovascularization. Patients with small drusen (also called hard drusen) are at relatively low risk for the development of choroidal neovascularization. Patients aged over 65 with bilateral large (soft) drusen have an approximately 6% risk to either eye of developing choroidal neovascularization each year. Overall, patients with large drusen in one eye and choroidal neovascularization in the other eye are at a 30% risk of developing neovascularization in the second eye within 5 years. When large drusen are combined with pigmentation and choroidal neovascularization in the first eye, risk to the fellow eye approaches 60% over 5 years. Laser photocoagulation in eyes with drusen may result in the resolution or disappearance of drusen. The natural hope would be that the disappearance of drusen would be paralleled by a decrease in the risk of developing choroidal neovascularization. The purpose of this study was to determine whether laser photocoagulation of the periphery of the macula can reduce the risk of visual loss from choroidal neovascularization in eyes with high-risk drusen.