A cataract, a degenerative condition that affects the eyes, is characterized by a loss of clarity of the lens.
• The lens is a transparent structure that focuses the light on the retina, allowing clear vision
• Opacity of the lens causes loss of vision that can range from mild to partial blindness
• The most common cause of cataracts in cats is uveitis (inflammation of the eye)
• Other causes include nutritional disorders, trauma, metabolic disorders, genetic factors, and glaucoma
• Diagnosis of the cause of cataracts may involve blood work, ophthalmic examination, and specialized testing of eye function
• Cataracts are not an emergency, and a blind cat can live a healthy life
• Treatment involves the surgical removal of the cataract or the administration of medications to resolve underlying inflammation
Cataracts can be categorized by age of onset.
Congenital: congenital cataracts are present at birth or soon after, this kind of cataract is generally due to genetic conditions.
Juvenile: juvenile cataracts can be caused by a number of underlying conditions and risk factors. Nutritional disorders due to the administration of certain kinds of milk substitutes are specific to juvenile-onset cataracts. Cataracts caused by toxicosis tend to affect younger cats as they are more likely to consume food indiscriminately.
Geriatric: older cats are more likely to develop cataracts as a result of underlying health conditions.
Some causes of cataracts can occur quite suddenly, such as cataracts due to trauma. Other types, such as those caused by uveitis, may have a slower onset.
Cataracts progress through several maturity stages:
Immature: Small opacity that does not affect vision
Mature: Widespread opacity with complete blindness
Hypermature: White, sparkly to clear lens with complete blindness
Cataracts can also vary in severity based on their location and shape.
Lenticular (or nuclear) sclerosis can be mistaken for cataracts. Lenticular sclerosis is the normal thickening of the lens that increases opacity as the cat ages.
Pet parents are often anxious about conditions related to eyesight loss in cats, as humans attach a great deal of emotional intensity to vision and vision loss. Cataracts are not a medical emergency. The gradual loss of vision generally does not cause extreme distress to house pets as they do not have to hunt or avoid predators.
Even though cataracts are not an emergency, prompt veterinary attention is required to treat cataracts. Surgery is the only treatment option. There are a number of eye drops on the market that claim to dissolve or cure cataracts, but there is no medical evidence supporting such claims.
A cataract is the clouding of the normally perfectly clear lens. Unlike other tissues in the body, the lens of the eye is very simple, composed of 60% protein and 40% water. Due to the limited components of the lens, the possible responses to injury or disease are limited. Any injury or disease in the lens results in a cataract.
Potential contributing factors and causes of cataracts include:
• Traumatic injury
• Nutritional disorders: certain types of milk replacements have been linked to the development of cataracts
• Metabolic disorders, such as diabetes mellitus
• Genetic predisposition
• Exposure to radiation
• Exposure to toxins
• Electric shock
The cloudiness of the lens causes loss of vision that can range from mild to partial blindness.
The most common cause of cataracts in cats is uveitis. Uveitis is a common and painful inflammation of the uvea, the part of the eye consisting of the iris, the choroid, and the ciliary body.
Symptoms of cataracts in cats:
• Changes in the color of the iris, or apparent cloudiness of the eye
• Decreasing agility
• Increasing clumsiness, including bumping into objects
• Difficulty locating food bowl and litter box
• Unwillingness to move around unfamiliar places
Cataracts are easily recognized by both primary care veterinarians and pet parents. Diagnosis, further characterization, and removal of the cataract require referral to an ophthalmologist.
Diagnostic tools include:
• Blood work • Urinalysis • Ophthalmologic exam • Orbital ultrasound • Electroretinography
• Specific testing for infectious conditions
Over time, patients with cataracts may develop uveitis or glaucoma, so routine monitoring is advised. If the cataract is not caused by glaucoma and there is no associated inflammation, it does not necessarily require treatment. Partially and completely blind animals have a good quality of life.
Treatment of cataracts and restoring eyesight involves:
Phacoemulsification: surgery that involves a small incision to the cornea and high-frequency ultrasound to break apart the cataract. Once emulsified, the lens tissue is removed. An artificial lens is then implanted to restore vision. This treatment is most effective during the immature or mature phases of cataract development.
Medication: Anti-inflammatory medications such as corticosteroids or NSAIDs to reduce inflammation in cases of uveitis
Supportive care: especially in the case of uveitis and glaucoma
If surgery is performed, post-surgery veterinary appointments are necessary to ensure proper healing of the eye. An Elizabethan collar can be used to prevent the patient from scratching the recovering eye.
Phacoemulsification surgery has a very high success rate.
In cases where the cat does not need treatment and has partial or total vision loss, a number of precautions can be taken to ensure the animal's safety:
• Indoor lifestyle to avoid risk from predators or cars
• Environmental control of hazards in the home
• Furniture should not be moved around the house so the cat does not get disoriented
Even though losing its eyesight is not a medical emergency, the affected pet may go through an adjustment period in which it may be anxious and act aggressively; ensuring a safe and stress-free environment is important to maximize outcomes and provide the best quality of life during this transitional period.
Cataracts are not contagious. There is no way to prevent cataract formation. Keeping up to date with vaccinations and annual veterinarian check-ups can help maintain general health and increase the likelihood of early detection.
Cataracts are rare in cats.
• Surgery • Supportive care • Corticosteroids
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