When to see a vet urgently
Contact a vet immediately if your cat develops any of the following:
- Sudden collisions, disorientation in a familiar room or loss of vision.
- Marked squinting, obvious eye pain or rapidly changed eye appearance.
- Breathing difficulty, seizures or collapse.
- Rapidly worsening eye signs with profound lethargy and refusal to eat.
You can find a vet near you.
Overview
The choroid and retina provide ocular nutrition and receive light signals. When inflamed, capillary circulation is disrupted, causing sight-threatening haemorrhages, swelling and degeneration. Chorioretinitis is rarely an isolated disease in cats; it most often complicates systemic infections or immune disorders.
The choroid belongs to the eye's middle, vascular layer, the uvea. Inflammation of this layer is called uveitis. When inflammation lies at the back of the eye and involves the retina, it is called chorioretinitis. The front of the eye may also be inflamed. Distinguishing these areas helps choose treatment because eye drops alone are insufficient for inflammation at the back.
The retina converts light into signals the nervous system processes. Inflammation can damage it locally or extensively. A small change at the back of the eye may therefore cause no obvious visual difficulty at home. External appearance also cannot establish how well the retina works.
Causes
The main causes of feline chorioretinitis include:
- Infectious diseases: FIP, FeLV, FIV, toxoplasmosis, bartonellosis and fungal infections.
- Autoimmune processes.
- Systemic inflammatory diseases, including chronic kidney inflammation and vasculitis.
- Eye injuries and intracranial damage.
- Tumours, including lymphoma and melanoma.
This list does not mean every condition is equally common or equally well established as a cause in cats. Kidney or another systemic disease alone does not explain inflammation. Injury is also assessed from events and the eye examination. In some cats with uveitis, the cause remains unknown despite investigation.
The association between bartonellosis and eye inflammation needs particular caution. The bacterium or antibodies can also be found in healthy cats. A positive result therefore does not establish Bartonella as the cause of retinal changes on its own.
Risk factors
- Chronic viral infection.
- Living in a rescue centre or outdoors.
- Kittenhood and young age, with greater susceptibility to toxoplasmosis and FIP.
- Older age with cancer or autoimmune disease.
Age and environment guide investigations but do not confirm diagnosis. Outdoor cats may have different exposures from indoor cats. Young cats also have several possible causes of eye disease. Evidence is not equally comprehensive for every listed risk factor, so testing is not restricted by age or housing alone.
Typical symptoms
Chorioretinitis involves eye and systemic signs:
- Impaired vision, potentially progressing to complete blindness.
- Dilated or unequal pupils.
- Cloudiness at the back of the eye on examination.
- Retinal swelling or haemorrhage.
- Inflammation of vessels at the back of the eye.
- Light sensitivity and nystagmus.
- Fever, lethargy and weight loss with systemic infections.
You may first notice hesitation before jumping or difficulty finding a familiar route. Good vision in one eye can conceal damage in the other. Not every posterior eye inflammation causes visible redness, so a quiet-looking eye does not rule it out. The findings at the back of the eye are identified during veterinary examination, not by looking at its surface at home.
A visible fundus change may be active inflammation or a scar from previous disease. The vet assesses features such as its borders and retinal appearance. An old scar alone does not prove continuing infection.
Complications and consequences
Untreated chorioretinitis can lead to:
- Permanent loss of vision.
- Retinal detachment.
- Glaucoma.
- Chronic uveitis.
- Progression of underlying disease, including FIP or toxoplasmosis.
Visual impairment depends on inflammation's extent and location. Damage around the optic nerve or extensive retinal detachment may matter much more than a small local scar. Controlling inflammation and restoring vision are different: existing tissue damage may remain permanent.
Diagnosis at the vet
Investigations include:
- Eye examination and ophthalmoscopy.
- Fluorescein angiography to assess retinal vessels.
- Blood tests, including biochemistry and antibody tests for toxoplasmosis, FeLV and FIV.
- PCR to identify infections.
- Eye ultrasound when internal structures are obscured by cloudiness.
- Neurological examination when systemic disease is suspected.
Initial FeLV testing usually looks for viral antigen, a component of the virus, whereas FIV screening usually uses antibodies. These are therefore not interpreted as equivalent antibody tests. An unclear result may require further investigation or repeat sampling according to the cat's situation.
Toxoplasma antibodies may indicate previous infection. A recent or changing result fitting symptoms provides different information from a stable marker of old exposure. Coronavirus antibodies do not confirm FIP alone either. PCR significance depends on the organism, sample and other findings. Each result is therefore always considered alongside symptoms.
Tell the practice when symptoms began, previous eye diseases, current medicines and possible injuries. Information about illness in other cats also helps the overall assessment.
The whole cat is examined alongside the eyes. Eye pressure measurement can identify low pressure associated with uveitis or glaucoma developing as a complication. Corneal staining looks for an ulcer; it differs from angiography of vessels at the back of the eye. Further tests are selected from findings rather than automatically performing the whole list in every cat.
Treatment and follow-up
Treatment aims to control ocular inflammation, relieve any pain and address the cause. A confirmed infection needs appropriate medication. Immune-mediated inflammation may need different treatment from infection. Posterior eye disease often requires medication acting throughout the body. The vet selects medicines and combinations.
Corticosteroid suitability is assessed before treatment because unrecognised infection may worsen with immune suppression. Corticosteroid eye drops are unsuitable for a corneal ulcer. Do not start old eye medicines for new symptoms: a similar-looking problem may have a different cause this time.
FIP no longer automatically means treatment is unavailable. Effective antivirals exist, and the vet assesses options for cats with eye signs too. The visual prognosis is assessed separately from the damage to the eye.
Check-ups assess inflammatory changes, eye pressure and the systemic disease's response. Do not stop medicines because appearance improves alone. Report new squinting, deteriorating vision or general condition so the plan can be reviewed.
The home environment with reduced vision
Keep feeding areas, water, the litter tray and furniture in familiar places. Clear routes and protect stairs and other fall risks. Do not place a poorly sighted cat high up and expect it to find a way down. Speak as you approach so touch does not startle it.
A safe indoor environment and protected outdoor access reduce hazards from impaired vision. Provide familiar games and opportunities to move at the cat's own pace. Record movement changes: they help describe function at check-ups even though you cannot assess inflammation at the back of the eye at home.
Prevention
- Vaccinate against the main viral diseases, including FHV-1, FCV and FeLV in at-risk cats.
- Maintain parasite control for Toxoplasma and Bartonella.
- Isolate ill animals when FIP or viral infection is suspected.
- Take chronically ill cats for regular eye examinations.
- Support immunity with good nutrition and care.
Vaccines prevent their target diseases but do not protect against every cause of chorioretinitis. Vaccinated cats can also acquire respiratory viruses. The vaccination plan, including FeLV protection, is based on individual exposure risk.
Bartonella are bacteria, and flea control is central to preventing their spread. Toxoplasma is a protozoan: reduce exposure by preventing hunting and avoiding raw or inadequately cooked meat. Ordinary worming is not a universal preventive measure for all these infections.
Isolation is agreed according to the confirmed or suspected organism. FIP alone does not require every affected cat to be isolated, but concurrent contagious disease may change the advice. Hand hygiene and clean litter trays are part of routine infection prevention.
Important for cat owners
Chorioretinitis always indicates serious disease. It most often complicates dangerous systemic illnesses. Remember that a sudden decline in vision warrants urgent veterinary care. Early diagnosis and treatment of the underlying disease improve the chance of preserving sight and life.
The finding always requires investigation but does not, on its own, establish life-threatening systemic disease. Unexplained inflammation or disease mainly affecting the eye is also possible. The prognosis depends on the identified cause, response and extent of ocular damage.
This article provides general information and does not replace veterinary care. Contact a vet if you notice signs of illness in your cat.
Frequently asked questions
Can chorioretinitis affect only one eye?
Yes. Uveitis may be unilateral or bilateral. Both eyes are examined because mild changes may not affect behaviour visibly at home.
Does a positive Toxoplasma test mean an eye infection?
Not alone. Antibodies may reflect earlier exposure. The vet assesses the test type, other findings and whether symptoms fit active toxoplasmosis.
Can a cat live well if vision does not return?
A cat can adapt to impaired vision in safe, familiar surroundings. Good quality of life also requires treatment of pain and underlying disease. The cause of blindness is investigated even when home adaptations are already in place.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
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