A model of subretinal neovascularization in the pigmented rat.

We produced krypton laser photocoagulation lesions of mild to moderate whiteness in the posterior retinas of one eye of 23 pigmented rats, and identical appearing argon laser burns in the fellow eyes. We observed foci of subretinal neovascularization, histopathologically markedly similar to that which occurs in several human retinal diseases, in the krypton laser treated eyes of 6 of the 14 rats that were followed for one to three months after photocoagulation. No such lesions were observed in the argon laser treated fellow eyes, nor in krypton or argon laser treated eyes examined earlier than one month after photocoagulation. The photocoagulation damaged only the choriocapillaris, the retinal pigment epithelium (RPE), and the photoreceptor layer. In the acute lesions, we did not observe ruptures in Bruch's membrane. The neovascularization was surrounded by multiple layers of RPE cells, a histopathologic finding that has also been reported in some human eyes with subretinal neovascularization in age-related macular degeneration. These observations suggest that the RPE cells may be modifying the proliferative behavior of adjacent choroidal capillaries. This model differs from previous models of subretinal neovascularization in primates, and may be useful for additional studies of this important pathological process.