Common eye problems in cats

As any kitty lover will tell you, a cat’s eyes can be mesmerizing. Here’s a look at some of the most common ocular problems in felines, including conjunctivitis.

As any kitty lover will tell you, a cat’s eyes can be mesmerizing. They’re also anatomically different from canine eyes – the elliptical iris opening is the most obvious difference. The conjunctiva of the eye is a feature that remains similar across species, but unlike dogs, conjunctivitis in cats is almost always associated with an infectious cause.

Causes of conjunctivitis

• Feline herpes virus-1 (FHV-1) can become chronic and recurring. stress is the usual cause of recurrences. The virus replicates in the upper respiratory tract, as well as the cornea and conjunctiva. if the infection is left untreated, secondary bacteria will cause an ocular discharge of ecru or green mucus. The infection is often bilateral.

Initially, you may notice the cat holding the eye partially or fully shut. The eye may be red with a clear watery discharge. a veterinary diagnosis is crucial, but once you know for sure your cat has FHV-1, begin oral lysine amino acid at 250 mg twice a day at the first sign of winking, and an OTc eye lubricant, preferably containing sodium hyaluronate meant for the eye. Place a drop in the eye every couple of hours until the blinking subsides.

• Chlamydia causes conjunctivitis without any respiratory signs. infection is usually unilateral, causing redness, swelling and serous to purulent eye discharges. infected cats often remain as carriers of mycoplasma, infecting other cats in the household. chlamydia also has zoonotic potential, and can spread to humans, especially the chronically ill, very young or elderly. always wash your hands after treating the eyes of an infected cat. conjunctival skin scrapings within the first two weeks of the infection can help with the diagnosis. chronic cases of chlamydia cause the formation of follicles on the conjunctiva – these are tiny raised white or red nodules. conventional treatment usually involves the use of topical antibiotics.

• Bordetella bronchisepticum, and occasionally calicivirus, can also cause conjunctivitis in cats.

• Mycoplasma causes unilateral or bilateral tearing, swollen conjunctiva with follicles, swollen eyelids and thick white secretions called pseudo-membranes. This infection responds to the appropriate antibiotic, both topically or orally.


Chronic conjunctivitis causes the goblet cells in the conjunctiva to atrophy, so protective tearing declines and the cat’s eye becomes dry and sticky. If the discharge becomes profuse and changes colour, topical antibiotics or antivirals may be needed from the veterinarian. Do not use OTc ocular antibiotic creams and drops designed for humans. Many contain an antibiotic that has been found to be toxic to cats.

Symblepheron is a consequence of chronic conjunctivitis in cats. The conjunctiva sticks to the surface of the cornea. it is felt that 50% of symblepheron cases are caused by FHV-1. symblepheron may block tear drainage if the conjunctiva is stuck at the inner corner of the eye. it can prevent the normal movement of the eyeball, and if it sticks over the iris, will block vision. Other causes may be foreign bodies, infection of the globe inside the eye, or some tumors. symblepheron does not need to be surgically corrected if it is not causing any complications to the cat’s vision or eye health.

Along with conventional medications, which are often necessary to address acute conditions, there are many alternative ways to treat conjunctivitis in cats (see sidebar). To help prevent these common eye problems, feed your cat a high quality meatbased diet, protect him from infectious disease without overvaccinating, and get his eyes checked by a vet at any sign of redness, tearing, discharge or squinting.


After completing an Herbalist diploma, Dr. Kneebone attended the Ontario Veterinary College. Upon graduation in 1981 she turned her focus towards natural medicine, and subsequently obtained diplomas in Homeopathy, Chinese Herbal Medicine and Veterinary Acupuncture. She is certified with the International Veterinary Acupuncture Society and is also a certified Ozone Therapist and member of The American Academy of Ozonotherapy. Dr. Kneebone has been with East York Animal Clinic in Toronto, Ontario since 1998.