The nictitating membrane, also called the third eyelid, serves as a layer of protection for cats and other animals. It also functions in keeping the surface of the eye moist. Although not normally seen in cats, on certain occasions, the nictitating membrane is momentarily visible as an opaque barrier covering the eye. Its prolonged presence may indicate infection or another health abnormality.Continue Reading
If the surrounding areas of the cat's eyes are retracted or depressed, the nictitating membrane may reveal a problem related to muscle spasms. Tetanus is a possible malady in this event. If muscle spasms are not present, the problem may be related to chronic weight loss or dehydration. The presence of the nictitating membrane in a single eye indicates a problem restricted to that individual eye, as opposed to a systemic illness if both eyes are affected.
Horner's syndrome is identified by the prolapse of the nictitating membrane, small pupils and a depressed area surrounding the eye. Injury to a certain nerve in the neck or a middle ear infection are possible causes. Haw syndrome, which also features exposed nictitating membranes, usually results from a gastrointestinal illness in cats under the age of two and clears itself after a few months, even in the event of no treatment.Learn more about Cats