Emerging biological therapies for age-related macular degeneration

Age-related macular degeneration (AMD) has emerged as the dominant cause of irretrievable visual loss in most developed countries achieving increasing longevity. The major cause of rapid and severe visual loss is the development of choroidal neovascularisation under the macula (exudative or wet AMD). Physical treatments, especially thermal laser and photodynamic therapy following intravenous verteporfin, have made statistically significant but modest progress in limiting visual loss, whereas surgical translocation of the macula and even light or electrically sensitive retinal implants are spectacular, but likely to only ever benefit a few. Intravitreal fine needle injections and slow release implants of steroid derivatives have opened new areas for investigation. The blocking of endothelial receptors for vascular endothelial growth factor by RNA-based aptamer or immune-protected antibody fragments has been the subject of intensive scientific development and large scale clinical trials. This approach may expand the range of AMD patients amenable to treatment. Additional therapeutic gains await measures to modify photoreceptor cell loss and subretinal fibrosis involving the retinal pigment epithelium as well as prevention or treatment for pigment epithelial detachment. Epidemiological associations with smoking and diet, and antioxidant dietary supplements offer important strategies for prevention.