Progressive retinal atrophy (PRA) is a hereditary disease of the eye that causes blindness. The retina is the tissue lining the back wall of the inside of the eye and is composed of two classes of photoreceptor cells called rods and cones; the rods function in dim light, and the cones in bright light. A dog affected with PRA begins to have difficulty seeing in dim light, … [Read more...] about Progressive Retinal Atrophy (PRA)