As a cat lover, don’t you hate it when people describe a great cat as being like a dog? As if dogs are somehow better than cats. When it comes to cataracts, cats should not be considered small dogs. Cats are way better than dogs when it comes to cataracts!
“Cataracts are not very common in cats and are much more common in dogs,” says Dr. Noah Plotsker, Comparative Ophthalmology Resident at Cornell’s College of Veterinary Medicine. “In one study, the estimated prevalence of cats with cataracts is around 13%. This difference is because the major causes of cataracts differ between dogs and cats. The most common causes of cataracts in dogs are genetics and diabetes mellitus. The most common cause of cataracts in cats is inflammation within the eye (uveitis).”
What They Are
Cataracts are defects in the ocular lens that minimally impair vision, and when severe, can result in complete blindness. They are most common in cats greater than 10 years of age, although they can happen at any age. Causes include:
- Chronic intraocular inflammation, uveitis
- Metabolic disturbances, diabetes, chronic kidney disease, chronic vomiting and diarrhea that lead to dehydration
- Trauma, penetrating injury to the globe resulting in intraocular inflammation/infection and/or disruption of lens fibers
- Nutritional, occurs in some orphan kittens fed milk replacer
- Idiopathic (medical term for unknown cause)
- Inherited, documented in some breeds, including Persian, Bengal, Himalayan, Russian Blue, British Shorthair, and Birman
“Many inherited cataracts are seen at the time of birth but are small enough that they do not impact vision,” says Dr. Plotsker. As such, these may not be apparent to the breeder. “It is important to ensure that your cat has an eye exam if you plan to breed him, as breeding cats with inherited cataracts is not recommended.”
Why We Care
In addition to vision loss, cataracts can cause painful, unmanageable secondary issues within the eye, including lens-induced uveitis (inflammation within the eye), glaucoma (increased intraocular pressure), and lens luxation (dislocation of the lens within the eye). This happens because the lens continuously degenerates over time, resulting in chronic inflammatory changes around it. Medical management of these secondary conditions is not always successful, leaving surgical removal of the blind, painful eye (enucleation) as the only option. This is why cataracts in cats should never be ignored.
Surgical Options
“Cats with heritable cataracts may be candidates for cataract surgery, while cats with cataracts secondary to uveitis are generally not considered candidates due to the inflammation in their eyes,” says Dr. Plotsker. “Some veterinary ophthalmologists do not recommend cataract surgery for cats due to the possible risk of a type of cancer known as feline post-traumatic ocular sarcoma (FPTOS). FPTOS is a malignant tumor that can occur following trauma to the lens, including surgery.”
Whether to have cataract surgery done on your cat is not a decision to take lightly. If you and your veterinary ophthalmologist decide the procedure is right for you and your cat, it may well be a big win-win, as surgical outcomes in cats are generally good, and leaving a cataract in place can result in painful, vision-destroying conditions that may necessitate enucleation.
The most common surgery used to address feline cataracts is called phacoemulsification. Small incisions are made in the cornea and the lens capsule. High frequency vibration is used to essentially pulverize the lens, which is then removed by vacuum. An artificial lens is inserted, and the cornea is sutured closed.
You can expect your cat to spend a few days in the hospital, receiving frequent post-surgical ocular treatments and close monitoring. Your cat will go home with an Elizabethan collar in place, and you will be required to administer frequent topical eye and oral medications. Recommended follow-up examinations are an important part of identifying and treating any post-operative complications that crop up to ensure a good outcome.
In cats, the most common short-term surgical complication is uveitis. The most common longer-term surgical complications include post-capsular opacities, synechia (adhesions between structures in the eye), and dyscoria (misshapen pupil), neither of which tend to cause issues or bother your cat.
Medical Management
What if your cat is not a candidate for surgery? The most common cause of cataracts in cats is uveitis, and cats with uveitis are not candidates for cataract surgery.
“Medical therapy is the mainstay of treatment for cataracts in cats,” says Dr. Plotsker. “If uveitis is present, and an underlying cause is found, treatment is started to address the underlying cause and the eye is treated with topical anti-inflammatories until the inflammation has subsided. Life-long anti-inflammatory eye drops are often recommended to address lens-induced inflammation which can lead to glaucoma.”
Cataracts in cats should never be ignored. If your cat develops a cataract, be sure to see your veterinarian to identify and treat any underlying causes, and to determine the best course of action for your cat. Whether that is medical management or surgical correction by a veterinary ophthalmologist, your cat will require frequent, careful monitoring for the rest of his or her life to ensure he or she continues to be pain-free and visual for as long as possible.
