Does My Cat Have Progressive Retinal Atrophy?

I have a cat that is a year old and for the last few months i've noticed his pupils don't respond to light that well. His pupils are very large at night and barely shrink when he's in light. When I shine light into he squints like it hurts his eyes and his pupils shrink only a little bit. I have another older cat and his pupils are no where near that big even in the darkest rooms. I know there pupils get much larger at night but even in the sunlight they are medium sized . Could this be pra? (Missy Tomas - Ontario)

You have obviously done your research and suggested with good cause that this might be Progressive Retinal Atrophy (PRA). The indications are strong that your cat maybe be beginning to suffer from this largely hereditary disease. When a cat suffers from PRA, the eye develops normally as a kitten but throughout adulthood the photorececeptors will degenerate, leading to total blindness at the age of 3 to 5 years. The outward appearance of the eye will usually be normal, although pupils will be noticeably more dilated (as you mention with your cat) and will reflect more light from the interior. Only in rare cases does the eye lens become opaque or cloudy. One of the first problems a cat will experience is night blindness.

You should take your cat to the vet, who can refer you to a veterinary opthalmologist for a decisive diagnosis. Unfortunately there is neither any way to slow the progression of this disease or to cure it. However, the outlook for blind cats is reasonably good, with cats being highly adaptive due to their reliance on hearing and smell. See the article below for more information.