Day blindness, also known as achromatopsia, is an inherited autosomal condition which is characterised by a failure of cone cells in the retina to function properly. Cone cells are responsible for vision in bright light conditions and rod cells function in dim light.
Standard Poodle puppies with the DB/RD form of day blindness manifest signs of poor vision in bright light but initially retain normal vision in low light levels. The DB/RD mutation causes a more complete retinal degeneration in the Standard Poodle compared to other breeds, and affected dogs eventually lose both cone and rod cell function. The end result is retinal degeneration and complete loss of vision.
Genetic testing can be used to identify carrier and affected animals.