In particular, it would not be helpful to patients suffering from diabetes or glaucoma, because these diseases damage nerve fibers in the retina that lead to the brain. The target diseases for this project, age-related macular degeneration and retinitis pigmentosa, are not rare. The former affects 700,000 Americans each year and is the leading couse of blindness in the Western world. Retinitis pigmentosa, while less common, affects 1.6 million people worldwide. It is the leading cause of inherited blindness worldwide.
Macular degeneration causes loss of the central part of the visual field, making reading impossible.
Retinitis pigmentosa initially causes gradual loss of peripheral vision followed by loss of central vision, eventually causing complete blindness. These two diseases share the anatomical problem of rod and cone degeneration. The rods and cones are the photoreceptors at the back of the retina that convert incoming light to neural signals. Degeneration of these cells leaves the retina insensitive to light. The patient can become blind, despite having a retina with an active connection to the brain through a functioning optic nerve.