Although cat’s and dog’s eyes have a number of differences which improve ability to hunt and night vision, the basic structure is much the same as a humans. Consequently cats can suffer a similar range of eye diseases to humans. Because the eye is complicated, delicate and very sensitive all eye problems require immediate veterinary attention. One of the most common eye disorders is a corneal ulcer.
A corneal ulcer is a hole in the surface layers of the clear covering (the cornea) of the front of the eyeball. Sometimes only the top layer of the cornea is affected but the damage may go deeper and may be more difficult to treat. There will often be a layer of dead tissue over the wound and the surface of the eye may appear cloudy. Usually the ulcer will only increase slowly in size but on rare occasions the wound can become infected with dangerous bacteria. These produce chemicals, which eat away at the surrounding normal tissue causing permanent blindness within a few hours.
In many cases the actual cause of the ulcer is uncertain. Many are probably caused by a scratch from another animal during play or a fight, a foreign body such as a piece of grit or grass seed embedded under the eyelid, a chemical irritant or eyelashes rubbing against the surface of the eye. Bacterial or viral infections can also cause damage as well as being a
secondary problem following physical injury. Dryness of the
eye is another possible cause of damage. Your pet may blink
frequently and the membranes around the eye may appear red and inflamed.
Ulcers can be very painful and your cat may hide and it may become unusually aggressive. The affected eye is usually very watery. Sometimes the third eyelid (a protective membrane which covers the eye when the main eyelid is closed) will cover the surface of the eye when the eye is open.
Local anaesthetic drops can be put in the eye to make your cat more comfortable. A few drops of fluorescent dye may be put into the eye, which will show the vet how far the ulcer extends. Your veterinarian will try to identify the cause of the ulcer in order to choose the best treatment.
Superficial injuries are treated with eye drops/ointments, antibiotics and anti-inflammatory. Deep ulcers must be protected by a third eyelid flap. The third eyelid can be drawn across the eyeball and sutured in place, under anaesthetic, to provide the essential protection for healing to take place.
The flap is usually left in place for approximately three weeks, at which time the veterinarian will examine the eye again to determine if the flap can be taken down.
© Forrest Hill Vets (2000) Ltd