ABSTRACT
age-related macular degeneration (ARMD) is the leading cause of visual loss among adults older than 65; 700 000 new patients are diagnosed annually in the USA, 10% of whom become legally blind each year. With increased average lifespan, the number of Americans with age-related eye disease and resulting visual impairment is expected to double. Photodynamic therapy and conventional laser therapy are two effective methods for slowing the progression of ARMD, while gene therapy and new surgical interventions, including localized ocular drugs, are currently being studied to help reverse blindness caused by retinal disease. The use of artificial means to treat extreme vision impairment has come closer to reality during the past few decades. Whether useful vision can be rendered via artificial visual prostheses depends upon establishing a definition of useful vision. Visual prostheses are based on neuronal electrical stimulation at different locations along the visual pathway.
