A cataract is an abnormality affecting the eye's lens that causes it to become opaque and a white or light blue-grey color rather than clear and transparent. An animal is blind if it has cataracts that involve the entire lens of both eyes. Cataracts most commonly affect dogs and often form because of a genetic predisposition, as a complication of certain diseases (e.g., diabetes mellitus), or because of injury to or inflammation of the eye.
Owners of older dogs often mistake a less serious and very common condition called lenticular sclerosis with cataracts, but a veterinarian can differentiate between the two disorders by performing a thorough eye exam. Once cataracts are diagnosed a general health work-up that includes blood work and a urinalysis is needed to search for any underlying disease that may have led to the formation of cataracts and to determine if the animal is healthy enough to undergo cataract removal surgery.
By far the most effective form of treatment for cataracts is surgery. A veterinary ophthalmologist will first assess an animal's chances of regaining vision before recommending that cataracts be removed. In many cases, removing the lens from only one eye allows animals to see well enough to go about their daily lives with ease. If surgery is not appropriate and the cataracts do not involve the entire lens, eye drops that cause the pupil to dilate may improve an animal's vision. It must be remembered that even if eyesight cannot be restored, blind dogs can still enjoy an excellent quality of life.
Written by: Jennifer Coates, DVM
Last reviewed: October 2, 2008