Photo by Brandon Heyer
Eyesight is extremely important for cats . They rely on this sense when they hunt and stalk their prey. It is very important to spot eye problems in your cat and treat them accordingly as early as possible. This should prevent more serious eye issues. A healthy eye is clear, bright, shiny, with no disturbing discharge. Common signs and symptoms of eye problems are described below.

If you notice one of the described conditions, take your kitty to a vet as soon as possible. No abnormal eye condition should be treated lightly and carelessly.

Eye discharge

A small amount of clear discharge is normal and shouldn't not be a reason for concern. Just like humans, cats can awaken with "sleepers" in their eyes. Excessive clear watery discharge with no pain and redness (or slight redness and itching) may be a sign of problems in the tear drainage system. This condition is called epiphora. It is a symptom rather than a specific disease, and it's associated with a variety of ailments including allergies.
A thick, sticky mucus discharge along with a red (inflamed) eye is usually a sign of conjunctivitis (also known as the Pink Eye). It's one of the most common cat eye issues. If only one eye is affected, the cat is most probably suffering from a virus such as Feline Herpesvirus (also known as Feline Rhinotracheitis). If both the eyes are affected, the cat is most probably suffering from a bacterial infection.

Painful eye

If your cat has excessive tearing, if it tends to keep the eye closed or half-closed, avoids light and if the eye is sensitive to the touch, most probably your cat has a painful eye. The cat may try to rub the eye with its paw. A painful eye can be a result of an injury to the cornea and various diseases such as feline glaucoma and uveitis. A painful eye can also accompany a number of serious cat conditions such as Feline Herpesvirus 1 (FHV-1), Feline Infectious Peritonitis (FIP), Feline Calicivirus, Feline Immunodeficiency Virus (FIV), etc.

Film over the eye

An opaque or whitish film that moves out over the surface of the eyeball from the inside corner of the eye is a protruded nictitating membrane (third eyelid). When a cat is healthy, you normally don't notice it. If you do, it is often a sign of physical or emotional stress. The kitty doesn't feel well.

Cloudy eye

Some diseases are known to influence the clarity of the eye turning it cloudy or making it look like a cat has a blind eye. This can vary from a small, localized haziness to complete opacity of the eye. All these are signs of an inner eye disorder. The typical diseases that cause a cloudy eye are keratitis, glaucoma, uveitis, and cataract. The latter is not associated with a painful eye while the others are. Even if the eye is entirely opaque, it may or may not be associated with a reduction in vision. In any case, a veterinarian should treat the problem as soon as possible.
Photo by Eran Finkle

Hard or soft eye

A hard eye with a dilated pupil indicates glaucoma. A soft eye with a small pupil indicates inflammation of the inner structures of the eye (uveitis).

Irritation of the eyelids

Swelling, crusting, itching, or hair loss are typical signs of irritation of the eyelids.

Bulging or sunken eye

These are abnormal contours of the eye. Anything that exerts pressure behind the eyes can cause them to bulge outward. For example, tumors, infections, glaucoma, and abscesses behind the globe. Glaucoma can sometimes develop very quickly. If your cat's eyes are normal today and bulging tomorrow, glaucoma is the most likely suspect. In some breeds, however, a bulging eye is kind of normal. These breeds are those with a shortened muzzle such as Persians, Himalayans, and Exotic Shorthairs.
Cats that are dehydrated or have rapidly lost weight may exhibit sunken eyes. Other causes are tetanus, a neck nerve injury or a middle ear infection.

Abnormal eye movements

Healthy eyes always focus in the same direction and never jerk back or forth. If you notice that it doesn't happen so anymore, take your kitty to a vet for a check up.

Cross-eyed gaze (strabismus)

Normally, the eyeball is held in place and is moved by small muscles attached directly to the eyeball. One muscle may sometimes happen to be longer or stronger than the muscle in the other eye. This causes the eyeball to veer off in an abnormal direction. One or both eyes may be affected. If both eyes deviate towards the nose, the cat is referred to as cross-eyed. In some breeds, crossed eyes are considered normal, and it is called medial or convergent strabismus. The Siamese is a typical example. In this case, no treatment is recommended as the abnormality is just a cosmetic problem that does not affect the quality of life.
Sometimes, however, strabismus is a result of injury to some of the eye nerves or muscles. If a formerly healthy cat has developed strabismus, it should be checked for vestibular system diseases. The vestibular system is part of the ear; it helps a cat (and people) keep the balance. If the vestibular system is not functioning normally, the cat may feel as if it's spinning, and its eyes will move abnormally trying to adjust to that. The underlying cause needs to be found and treated.

Colour change

Cat eyes are fully developed by the age of about three months. If you notice eye colour changes in an adult cat, it may be a sign of eye damage or a serious underlying condition such as melanoma (type of cancer). In most cases, however, it's caused by an eye infection, which should be treated as early as possible.
Cats suffering from uveitis often develop abnormally yellow or red-orange coloured eyes. A yellowish tint to the sclera can be s sign of jaundice.