Retinal Atrophy (Vallhund Type) affects dogs and is an inherited eye disease. This disease occurs due to degeneration of both Rod and Cone type Photoreceptor Cells of the Retina, which are important for vision in variable light. Affected dogs can first show evidence of this disease during an eye exam as early as 2 months of age. However, first signs of vision loss occur later and have been reported from 1 to 12 years of age. Rod type cells are affected first and dogs will initially have vision deficits in dim light (night blindness). Signs of progressive retinal atrophy on an eye exam involves changes in reflectivity and the appearance of a structure behind the retina called the Tapetum. The disease follows a variable progression, but most dogs will usually progress to complete blindness as early as 9 years of age.