Primary lens luxation is an inherited abnormality of the eye affecting several breeds of dogs. It is characterized by dislocation of the lens in the eye due to the breakage of the ligaments (called zonules) that hold the lens in place. The age of onset is variable depending on whether a dog has one or two copies of the Mutation, but affected dogs typically present between 2 to 8 years of age with sudden signs of eye irritation. Symptoms of lens luxation include excessive blinking, squinting and tearing of the eye. Dislocation of the lens can occur in both the forward and backward position within the eye, but dislocation in the forward position is more common and serious. If not treated immediately, lens dislocation can lead to Glaucoma and vision loss.
Reference: Pawprint Genetics
Progressive retinal Atrophy, Rod-cone dysplasia 4 (PRA-RCD4) is a late-onset inherited eye disease affecting dogs. Affected dogs begin showing clinical symptoms related to retinal degeneration between 7 to 12 years of age. Initial clinical signs of progressive retinal atrophy involve changes in reflectivity and appearance of a structure behind the Retina called the Tapetum that can be observed on a veterinary eye exam. Progression of the disease leads to thinning of the retinal blood vessels, signifying decreased blood flow to the retina. Affected dogs initially have vision loss in dim light (night blindness) and loss of peripheral vision, eventually progressing to complete blindness in most affected dogs.
Progressive retinal Atrophy, progressive Rod-cone degeneration (PRA-prcd) is a late onset, inherited eye disease affecting many breeds of dog. PRA-prcd occurs as a result of degeneration of both rod and cone type Photoreceptor Cells of the Retina, which are important for vision in dim and bright light, respectively. Evidence of retinal disease in affected dogs can first be seen on an Electroretinogram around 1.5 years of age for most breeds, but most affected dogs will not show signs of vision loss until 3 to 5 years of age or later. The rod type cells are affected first and affected dogs will initially have vision deficits in dim light (night blindness) and loss of peripheral vision. Over time affected dogs continue to lose night vision and begin to show visual deficits in bright light. Other signs of progressive retinal atrophy involve changes in reflectivity and appearance of a structure behind the retina called the Tapetum that can be observed on a veterinary eye exam. Although there is individual and breed variation in the age of onset and the rate of disease progression, the disease eventually progresses to complete blindness in most dogs. Other inherited disorders of the eye can appear similar to PRA-prcd. Genetic testing may help clarify if a dog is affected with PRA-prcd or another inherited condition of the eye.
Reference: Pawprint Genetics