Common causes of blindness in cats
Sudden blindness and progressive blindness in cats
A cat's eyes are mysterious, intriguing and simply astonishing. Built to be able to see much better than humans in the night, a cat's eyes are large compared to the size of the head, typically like other nocturnal creatures. The protruding eyes are built to have a good peripheral vision allowing the cat to effectively capture movement and stalk and prey literally in the blink of an eye. However, as beautiful as they can be, a cat's eyes are also vulnerable and prone to eye problems, some even with the potential of leading to blindness.
Owners may not be able to recognize right away a cat's vision loss in one eye. This is due to the fact that cats are really good in compensating with the other eye. Flashing a light towards the eyes is not really a reliable test to use in checking for eyesight as the pupils may still constrict as a reflex. However, there are other tests that can be done that may be more effective in determining vision capabilities.
A cotton ball may be dropped both in front of the cat and sideways. The cat's eyes should respond promptly in following the cotton ball's descent. A cotton ball works well, as it makes no noise as it drops so it can be a good way to determine eye sight. A cat's eye should also respond to a finger approaching the eyeball and should move away or shut the eye as a defense.
Cats suffering from blindness may have difficulties in actions such as jumping from a chair to another or they may have trouble getting around at night and bump against furniture. They may also be seen carrying their heads low in an attempt to use their whiskers in order to determine the location of objects around.
Blind cats may also sleep more than usual and get startled when an owner approaches them. They may as well appear lethargic and refrain from playing as usual. The pupils may appear dilated most of the time and in case of high blood pressure some blood may be seen in the eye chamber.
Causes of Blindness in Cats
Blindness may appear gradually or suddenly.
High blood pressure
This is the most common cause of sudden blindness in cats. High blood pressure is most often an "accompanying" disease showing in cats affected by diabetes, hyperthyroidism, and kidney disease. The eyes may appear with dilated pupils and the eye may present blood shot. The loss of vision is due to the retinas detaching. If treatment is seen promptly, there are chances the cat may regain vision once the blood pressure is bought back to normal.
In this case the eye is very painful and cats may suffer from eye sensitivity. The cat may squint and the eye may be watery. Affected eyes may also appear redenned or "muddy" and the pupil may appear small. Upon palpation, the eye may feel soft like a grape. This condition may potentially lead to blindness.
Trauma to the eye
Corneal ulcers are injuries of the eye. If left untreated corneal ulcers may develop complications and even loss of vision. It is imperative not to use any eye drops containing cortisone to treat corneal ulcers as this may causea ruptured cornea and blindness.
The eye's lens will appear opaque and this will interfere with the transmission of light to the cat's retina. While cataracts is rare in cats, it does have the potential to cause blindness. Cataracts should not be confused with "Nuclear Sclerosis" a bluish haze seen in senior cats which commonly does impair vision.
In this condition the eye develops pressure from fluids unable to escape the eye. This pressure causes the eye to enlarge and buldge. Tonometry done by an eye specialist may reveal high pressure within the eye. Glaucoma may cause permanent vision damage with loss of eye sight.
Progressive Rethinal Atrophy
In this case, hereditary components play a role. While seen mostly in dogs some cats have been reported to suffer from this too. It is seen often in Abyssinians. There is no treatment for this condition which ultimately results in blindness. The condition is not painful however, it is progressive but the cat will ultimately learn to use its other senses to get around.
Not many people are aware that cats require taurine to maintain good vision. Taurine is present in meats and cats that are only fed dog food may suffer retinal degeneration of the eyes and blindness if they lack this important amino acid. Most complete cat foods contain sufficient amounts of taurine.
Iris melanoma may develop and cause blindness in the eye. Tumors in the brain and eye lids as well may cause vision loss. Enucleation (removal of the eye) may be necessary.
As sad as it may be to learn that a cat has lost its sight, cats have demostrated enormous abilities to cope with the vision loss and lead almost normal lives. With some support, such as using ramps to climb into bed and refraining from making major environmental changes, cats may live decent lives compensating with their sense of smell, hearing and with those great radar like aids called whiskers.