The results of this work will provide insight into the mechanism of vision loss among patients with diverse retinal disorders. Specifically, we will study cone structure and function in patients with retinal degenerations with different etiologies: retinitis pigmentosa, a disease usually caused by rod-specific mutations; cone-rod dystrophy, which primarily affects cones rather than rods; and Best's disease, a disease caused by a defect in the retinal pigment epithelium (RPE). In addition, we will study the effect that lipofuscin, a byproduct of photoreceptor metabolism that accumulates in the RPE in diseases such as Stargardt's disease, Best's disease and age-related macular degeneration (AMD), has on cone structure and function, with the goal of understanding how these diseases cause blindness. Better understanding of the mechanisms of vision loss in patients with retinal degeneration should ultimately lead to treatments for these blinding conditions.