A novel form of retinal phototoxicity has facilitated investigation of the effect of retinal pigment epithelial (RPE) damage on the choriocapillaris of the rat. In response to isolated RPE injury, the choriocapillaris buds, digests the endothelial basement membrane, and projects pseudopodia that erode Bruch's membrane. The development of subretinal neovascularization in one of the rats demonstrates that breaks in Bruch's membrane may result from this lytic process and that neither degeneration of Bruch's membrane nor a preexisting break is essential for subretinal neovascularization to occur.