Retinal Swelling in Cats

Eye problems are most commonly found in cats who are middle-aged and older. Often, eye issues develop with no other health problems, however many different diseases and infections can also cause eye damage. Retina swelling specifically can be caused by a number of different underlying issues. This swelling can create irreversible loss of eyesight the longer it exists. Early detection is key to help save the cat’s vision, although identification of causative health issues may be challenging.

The retina is a component in the eye that receives light information from the lens and transmits this information to the brain as vision. It is a membrane lining on the interior of the eyeball that is extremely sensitive. The tapetum lucidum is a layer of tissue that sits below the retina, reflecting light for better sight. Because a cat's retina is so complex, they can see approximately six times better than humans in both lighter and darker scenarios. This complex eye is unfortunately prone to injuries and diseases. 

In the early stages of retinal swelling, no symptoms may be present. The more severe and the longer that the swelling has been present, the more symptoms will begin to manifest. Possible symptoms include:

• Squinting
• Blinking
• Enlarged eyeball
• Protrusion of third eyelid
• Dilated pupils
• Changes in the iris color
• Eye discharge
• Blindness

Any disease or injury that increases pressure in the eyes can produce retinal swelling. All types of infections have the potential to damage a cat’s eyes. Underlying causes known to create swelling in the eye are listed below.

• Retinal atrophy (degenerating retinal tissue)
• Conjunctivitis
• Cancerous or benign tumors
• Bacterial infection
• Viral infection (including feline immunodeficiency virus, feline leukemia virus, feline infectious peritonitis and feline herpesvirus)
• Fungal infection
• Parasitic infection
• Upper respiratory tract infection
• Papilledema (optic disc swelling)
• Hydrocephalus (excessive cerebrospinal fluid in the brain)
• Mucous membrane inflammation
• Genetic predisposition (as seen in the Abyssinian cat breed)
• Diet deficiencies 

Checking your cat's vision should be a part of regular veterinary examinations. This can help identify eye problems early. If symptoms of retinal swelling are arising, bring your cat to a veterinary clinic to be assessed professionally. Your veterinarian will need to know the cat’s full medical background and will complete a physical examination of the cat. Many different tests may be needed to pinpoint a correct diagnosis.

Often, affected eye cells will be collected from a scraping biopsy. These cells will be frozen and sent to a specialized lab or university to be tested further. A culture cytology may be done to evaluate and identify any bacteria or viruses present through microscopic examination. Immunofluorescent antibody testing is sometimes performed, using a special green dye applied to the eye that shows any ulcers or erosion on the surface. 

A polymerase chain reaction (PCR) test can also be helpful in diagnosing retinal swelling. Blood work including a complete blood count can be used to identify cancer in the body. X-rays or an MRI may be requested if a tumor is suspected. Blood pressure should be checked in case of hypertension. 

The appropriate treatment depends very much on any underlying health problems found in the cat. Greater success is associated with treating conditions early in their progression.

Antibiotics 

If a bacterial infection has been identified, the corresponding antibiotics can be administered to remove the harmful bacteria. If surgery is needed, a broad range antibiotic is often prescribed to ward off infection. These antibiotics can be in the form of drops or may be taken orally. Prescriptions tend to last one to four weeks.

Antifungal Medication 

If fungal spores have caused infection in your cat, applying antifungal medication can help eradicate the issue.

Antiviral Medication 

While some viruses do not respond to medication, success has been found in certain cases from prescribing antiviral medication. Prescribed medications can include trifluridine, idoxuridine or vidarabine.

Surgical Removal

In the case of eye tumors, surgical removal can help to restore eyesight and stop symptoms. If tumors are cancerous, it can also help reduce risk of metastization. As eye surgery can be complicated depending on the location and because of a cat’s small size, certain risks are associated with this treatment option. General anesthesia is required for the procedure. In cases which the tumors are numerous or the cancer is aggressive, it may be the safest course of action to remove the entire eye. Chemotherapy or radiation treatment may also be necessary.

Oral Lubricant 

Lubrication may alleviate squinting or blinking due to swelling and dryness. These lubricants often contain sodium hyaluronate.

Supplements 

Strengthening the immune system by increasing antioxidants can help prevent herpesvirus outbreaks in your cat.

If retinal swelling has been present for a long period of time, permanent blindness is possible. Depending on the underlying cause of health issues, eye damage is often irreversible. Early treatment carries the best prognosis for saving or restoring vision to the cat.

If your cat has been diagnosed with a feline virus, in most cases this virus will stay present in the cat’s system throughout its life. Reducing stress and strengthening your cat’s immune system can help prevent flare-ups of symptoms. Invest in a high-quality cat food to ensure your cat has no deficiencies, and discourage your cat from eating dog food. Certain vital ingredients for cats are absent in dog food and it should never be used as a substitute.