Cats' normal vision is superior to that of humans, but they are also susceptible to many of the conditions that affect our vision. Fortunately, many eye diseases can be caught early and treated, while others can be reversed. Even if your cat does lose its vision, chances are it can continue to live a full and happy life.
Common Causes of Vision Loss in Cats
As in humans, blindness can be caused by a huge range of issues. Eye disease, injury, infection, and cancer are among the most common causes. Here are some potential eye-related issues to be aware of.
- Cataracts (opacity of the lens) is rarer in cats than dogs. Because cataracts can lead to glaucoma, it is important to search out and treat the underlying cause if cataracts are found. Surgery to remove the affected lens is possible in qualified cats, and lens implants are sometimes used to approximate normal vision.
- Glaucoma (increased pressure within the eye) is one of the most prevalent causes of blindness in cats. It can be treated in early stages with medication to help reduce the intraocular pressure. These treatments may require hospitalization. A recently developed calcium channel blocker may also help to prevent damage to the retina and optic nerve. In advanced cases, surgery may be indicated.
- Eye tumors include Iris Melanoma, tumors of the eyelid, and other types of tumors. Removal of the eye is often necessary, but a prosthesis may be inserted to retain the normal appearance of the eye. Secondary glaucoma may be caused by a tumor.
- Progressive Retinal Atrophy (PRA) is an untreatable condition that is most likely inherited. It progresses slowly but eventually results in total blindness. The condition is not painful, and because of its gradual nature, cats usually learn to cope quite well with their decreasing ability to see.
- Injury to the eye is an emergency situation, and the cat needs to be seen immediately by a veterinarian.
- Conjunctivitis is an inflammation or reddening of the pink membrane that lines the eyelid, often causing "squinting eyes." Herpesvirus (FHV-1) is often the source of conjunctivitis in cats' eyes. Its treatment is often difficult, and the virus may resurface time and again over the lifetime of the cat. Stress is a key factor in repeated instances of FHV-1. Attendant corneal involvement can compromise vision, so it is important that a cat with ongoing conjunctivitis be seen regularly by a veterinarian, or better yet, by a veterinary ophthalmologist. Chlamydia and Mycoplasma can also cause conjunctivitis and all three organisms may be present at once, further complicating treatment.
- Untreated Feline Hypertension is by far the greatest cause of "sudden blindness" seen by veterinarians. Hypertension often accompanies diabetes, hyperthyroidism, and kidney disease, and cats with any of those conditions should be monitored closely by a veterinarian for evidence of hypertension. There are few early symptoms to watch for at home, but red flags include dilated pupils which do not respond to light and the appearance of blood in the eye chamber. Sudden blindness is always considered a medical emergency, and the cat should be seen by a veterinarian without delay. Feline Hypertension is handled primarily by treating the underlying condition. At the present time, there are no medications approved for cats with this condition, although a low-sodium diet may be prescribed by your veterinarian.
Seeing a treasured cat go blind, either gradually or suddenly, can be a devastating experience because we tend to equate vision loss in cats with human blindness. We need to remember, though, that cats are terrifically resilient. Cats don't need seeing eye dogs find their way around, nor do they need to learn braille in order to communicate. They will use their enhanced senses of smell, hearing, and touch (whiskers and other vibrissae hairs on their feet and their face) to compensate for their vision loss, so well that casual visitors may not even be aware that your cat is blind.
You can help a great deal by keeping your cat's normal routine as unchanged as possible. His food dish, bed, litter box, and other accouterments should be kept in their normal places. Try to avoid moving furniture, and keep other "stumbling blocks" out of his way. You can warn him of your approaching by speaking to him or clapping your hands. (He will also feel the vibrations of your footsteps on most floors.) Most importantly, relax and enjoy your cat. Whether blind or seeing, his feelings for you haven't changed.