Cloudiness of the Eye Lens in Dogs
Cataract refers to the cloudiness in the crystalline lens of the eye, varying from complete to partial opacity. When the eye lens (located directly behind the iris) is clouded, it prevents light from passing to the retina, which can cause vision loss.
Most cases of cataracts are inherited. For instance, Miniature poodles, American cocker spaniel, miniature schnauzer, golden retrievers, Boston terriers, and Siberian huskies are all predisposed to cataracts.
Symptoms and Types
Symptoms typically relate to the degree of vision impairment. Dogs with less than 30 percent lens opacity, for example, display little or no symptoms, whereas those with more than 60 percent opacity of the lens may suffer from loss of vision or have difficulty seeing in dimly lit areas.
Meanwhile, if your dog has diabetes mellitus-related cataract, you may also observe increased thirst, increased frequency of urination, and weight loss in your dog, along with vision impairment symptoms.
Although most cases of cataracts are inherited, the following are other causes and risk factors associated with the condition:
- Diabetes mellitus
- Old age
- Electric shock
- Inflammation of the eye's uvea (uveitis)
- Abnormally low levels of calcium in blood (hypocalcemia)
- Exposure to radiation or toxic substances (e.g., dinitrophenol, naphthalene)
If you should observe cloudiness in one or both of the dog's eyes, you should bring it in to see a veterinarian immediately. There, the veterinarian will ask for a thorough history of your dog’s health, including the onset and nature of the symptoms, and possible incidents that might have precipitated the problem. He or she will then perform a complete physical examination, focusing on the eyes and ocular region, to determine the severity of the problem.
Routine diagnostic tests, such as complete blood count, biochemistry profile, and urinalysis, may be conducted. However, the results of these tests are usually non-specific unless another concurrent disease like diabetes mellitus or hypocalcemia are at the root of the problem. Ultrasounds or electroretinography (which measures the electrical responses of cells present in the retina) are two forms of advanced diagnostic exams which also help determine the severity of the issue and may confirm whether surgery is necessary to correct a cataract.
If surgery is recommended by your veterinarian, do not delay. Cataract is a progressive disorder that, if not treated quickly, may lead to blindness in one or both of your dog's eyes. This is especially the case with diabetes mellitus-related cataracts, because they progress very rapidly in dogs. Surgery, however, is often not recommended for dogs with non-hereditary forms of cataract.
One modern cataract surgical technique, phacoemulsification, involves the emulsification of the eye's lens with an ultrasonic handpiece. Once the lens is emulsified and aspirated, aspired fluids are replaced with a balanced salt solution. Also, to prevent extreme farsightedness, an intraocular lens may be implanted during surgery. Phacoemulsification has shown more than a 90 percent success rate in dogs.
Living and Management
The rate of progression of this disease depends on the underlying cause of the cataract, the location of cataract, and the age of the animal. If your dog has undergone surgery to treat the cataract, it may require some time to recover in the hospital. Once home, your veterinarian will provide you with ophthalmic preparations to be used in the eyes of your dog for up to several weeks.