Overview A cataract is a cloudiness to the normally clear lens of the eye that scatters light as it enters the eye. The scatter of light may initially only result in a blurry image, but may progress to cause blindness. This may be compared to a window that is frosted or fogged with steam. A cataract can affect anywhere from 1 percent to 100 percent of the lens. The more of the lens affected, the worse the visual impairment. There are many misconceptions about cataracts: It is not a film over the eye, not a cancer, not spread from one eye to the other, and not a cause of irreversible blindness.
Causes The causes of cataracts are numerous. They include heritable (genetic) conditions, aging degeneration, congenital (birth defects), diabetes (in dogs), nutritional, electric shock, and trauma. Older dogs, just as older people may also develop cataracts as an aging degeneration. Some ophthalmologist have the impression that this may be exacerbated by ultraviolet (UV) exposure.
Cataracts will develop in ALL dogs afflicted with diabetes. In some cases, this may be a very rapid onset causing acute blindness. In others, cataract formation may be slowly progressive. Proper control of the diabetes will aid in slowing the onset of cataracts.
Symptoms Development of cataracts may be noted with other disease of the eye including inflammation of the iris (coloured part of the eye), glaucoma or diseases of the retina. Animals affected with cataracts secondary to other eye diseases are typically poor candidates for cataracts. Clues you may note if your pet has cataracts would include cloudiness to the eye or diminished vision (seems clumsiness, bumping into objects, or missing toys). If you are suspicious, seek evaluation by your veterinarian.
Diagnosis A thorough eye exam by an ophthalmologist can detect the presence and extent of a cataract as well as any other conditions that may cause diminished vision or cloudiness to the eye, particularly those involving the retina or optic nerve. If these problems are present, vision may not return after cataract removal. Early evaluation of a cataract is recommended to monitor for other possible complications that may be caused by cataracts, and to monitor for the appropriate time for removal.
Treatment Presently, there are no medications or dietary supplements that have been proven to treat cataracts. Surgical removal is the only option to retain or restore vision. It is not true that cataracts need to be "ripe" prior to being removed. With the newer techniques for cataract removal used in people and animals, early removal will achieve a higher success rate for restoration of vision.
It is a misconception that cataracts are removed with laser. They are removed using ultrasound waves which shatter the lens into small fragments for easy removal from the eye. The diseased lens of the eye is removed with removal of the cataract. The option of a permanent artificial lens implant is available for small animals (dogs and cats) with cataract removal to restore crisp, clear vision. Success rate for restoration of vision with cataract removal is in excess of 90 percent.