If your cat exhibits any sign of an eye infection, take him to the veterinarian as soon as possible. Treatment of feline eye infections depends upon the cause, but delay in care could threaten your cat's vision. Depending on the diagnosis, your cat might require topical eye medications. Complications of eye infections could require surgery.
Perhaps the most common feline eye infection, conjunctivitis is colloquially known as "pinkeye." Symptoms include squinting, a green or yellow discharge, and swollen, reddish conjunctiva that gives the condition its nickname. Conjunctivitis can result from bacterial, fungal or viral infection, or from certain eye diseases. Your vet must determine the cause of the conjunctivitis, and treat it accordingly. She will swab the eye discharge for analysis. While the feline herpes virus is the most frequent cause, your vet must rule out other possibilities.
Cats exposed to chlamydophila felis, the bacteria responsible for chlamydiosis, exhibit signs of infection within 10 days. Formerly known as feline pneumonitis, the infection always causes conjunctivitis but rarely causes pneumonia, although some cats might sneeze or have some nasal discharge. Cats younger than a year are most at risk, with older felines seldom developing chlamydiosis. Treatment includes ophthalmic ointment containing tetracycline, along with long-term oral administration of that antibiotic. While a feline vaccine against chlamydiosis is available, it does not proved 100 percent protection in inoculated cats.
Feline Herpes Virus
If your cat experiences conjunctivitis along with an upper respiratory infection, he might be suffering from the feline herpes virus. Since most cats have been exposed to the virus or been vaccinated against it -- which isn't 100 percent effective -- there's usually a stress-related trigger that causes recurrence. That might include any changes in the household or a stay at a boarding facility. Unfortunately, in some cats the eye infection is complicated by a corneal ulcer, which can cause vision loss. It's also possible that a cat recovers from one bout of feline herpes virus, only to have additional recurrences over time.
Feline Herpes Virus Treatment
Your vet most likely will diagnose feline herpes virus in your cat based on clinical signs. While she might prescribe antibacterial topical eye medications, they are ineffective on the virus itself, but can prevent or cure secondary infections. If there's corneal involvement, your vet might prescribe topical anti-viral eyedrops, which require frequent administration. She might recommend giving lysine to your cat, since this amino acid can help prevent feline herpes virus reproduction. If your cat isn't up to date on his vaccinations, your vet might use the nasal version of the herpes virus vaccine to boost the cat's immune reaction.
If the herpes virus infection has damaged your cat's cornea, additional treatment is necessary. If an ulcer develops on the cornea, your vet will need to debride it, or remove the affected tissue. That surgery requires anesthesia. Cats with corneal damage might develop dry eye, which requires regular topical medication to replace lost tear production.