Two major groups of diseases termed retinitis pigmentosa and age-related macular degeneration are the leading causes of blindness. In these diseases, loss of vision is due to progressive degeneration of the light sensitive cells of the eye or defects in the supporting cells of the eye. There is no cure for this at present although several have been suggested from studies on experimental animals, mostly rats and mice with similar diseases. One of these involves the transplantation of cells to slow the degeneration of photoreceptors or replace photoreceptors lost by the disease. My work explores this approach with the object of finding the best conditions for transplantation, identifying events that might compromise transplant efficacy and finding solutions to their deleterious effects, and specifically an assessment of how much visual improvement might be expected from this approach.