The effects of bFGF on RCS rat eyes.

Basic fibroblast growth factor (bFGF) has been implicated as a factor in retinal differentiation and disease. Recent studies have shown that subretinal or intravitreal injections of bFGF delay the retinal degeneration of the RCS rat but the global nature of this effect has been quantified for few test animals and the mechanism underlying this effect is not understood. In order to determine more accurately the global effects of intravitreal bFGF and to further elucidate the mechanism of bFGF promoted photoreceptor cell saving, we injected one of three bFGF doses into the vitreal cavities of young RCS rats. Using measurements from several eyes, we confirmed that a single intravitreal bFGF injection globally delays the RCS dystrophy. Test eyes contained fewer debris zone macrophages and more inner retinal macrophages than did control eyes at 1 month post injection. As bFGF's saving effect waned, the number of inner retinal macrophages decreased and the number of debris zone macrophages increased toward control levels. Dose-dependent cataract formation occurred in 100% of test eyes. Eyes that received the highest bFGF dose showed increased retinal vascularization at 1, 2 and 3 months post injection. The possible relationships between bFGF promoted photoreceptor survival and our findings are discussed.