CONDITION
Uveitis
Why this matters now
Uveitis is inflammation within the eye, affecting the uveal tract—the iris, ciliary body, and choroid. It occurs in both dogs and cats and can result from numerous underlying causes, both local and systemic. The condition is significant because untreated uveitis can lead to permanent vision loss, glaucoma, or other serious complications. Identifying the underlying cause is often as important as treating the eye itself, as uveitis frequently signals disease elsewhere in the body.
Uveitis can present acutely with sudden onset of a painful, red eye, or develop more insidiously with gradual changes. The inflammation disrupts normal eye function, causing protein and cells to leak into the fluid chambers of the eye. Without treatment, scarring and adhesions form between structures within the eye. Complications include secondary glaucoma (from blocked fluid drainage), cataracts, lens luxation, and retinal detachment. Chronic or recurrent uveitis carries the highest risk of permanent damage.
Signals & patterns
Early signals
Red eye
Redness of the sclera (white of the eye) or conjunctiva often develops with inflammation.
Squinting or holding the eye closed
Pain causes blepharospasm—the eyelid held partially or fully shut.
Excessive tearing
Watery discharge from the affected eye is common.
Cloudiness within the eye
The normally clear fluid chambers become hazy with inflammatory debris.
Pupil changes
The pupil may be constricted and respond poorly to light, or appear irregular.
Later signals
Colour change of the iris
Chronic inflammation can alter iris pigmentation.
Visible opacity or cataract
Secondary cataract formation clouds the lens.
Enlarged or bulging eye
Secondary glaucoma causes increased pressure and eye enlargement.
Shrunken eye
End-stage disease can result in phthisis bulbi—a shrunken, non-functional eye.
Vision impairment
Behavioural changes suggesting reduced vision in the affected eye.
Click to read about the biological mechanisms
How this is usually investigated
Diagnosis involves thorough eye examination and, often, investigation for systemic disease. Identifying the underlying cause guides treatment and helps predict outcomes.
Ophthalmic examination
Blood tests
Retroviral testing in cats
Chest and abdominal imaging
Aqueous or vitreous sampling
Options & trade-offs
Treatment aims to control inflammation, preserve vision, and address any underlying cause. The approach depends on severity, identified cause, and whether one or both eyes are affected.
Topical anti-inflammatory medication
Eye drops or ointments containing corticosteroids or non-steroidal anti-inflammatory drugs.
Trade-offs: Mainstay of treatment for anterior uveitis. Frequency depends on severity. Corticosteroids are more potent but contraindicated if corneal ulceration is present.
Topical mydriatics
Eye drops that dilate the pupil and relax the ciliary muscle.
Trade-offs: Reduces pain and prevents adhesion formation between the iris and lens. Atropine is commonly used.
Systemic anti-inflammatory medication
Oral or injectable corticosteroids or non-steroidal drugs.
Trade-offs: Necessary for posterior uveitis or severe cases. Duration depends on response and underlying cause. Systemic side effects possible with prolonged use.
Treatment of underlying cause
Specific therapy targeted at identified infectious or immune-mediated conditions.
Trade-offs: Essential for resolution in many cases. May involve antibiotics, antifungals, or immunosuppressive drugs depending on diagnosis.
Monitoring for complications
Regular assessment of intraocular pressure and lens clarity.
Trade-offs: Secondary glaucoma and cataract require early detection. Additional treatment may be needed if complications develop.
Common misconceptions
"A red eye is always conjunctivitis"
Whilst conjunctivitis is common, a red painful eye can indicate uveitis, glaucoma, or other serious conditions. Distinguishing between these requires examination, as treatments differ significantly.
"Uveitis only affects the eye"
Uveitis is frequently a sign of systemic disease. Thorough investigation often reveals underlying conditions that require treatment beyond the eye itself.
"Once the eye looks better, treatment can stop"
Uveitis often requires prolonged treatment. Stopping too early risks recurrence and complications. Treatment duration is guided by examination findings, not appearance alone.
Recognising that a painful, red eye warrants prompt assessment helps prevent complications from delayed treatment. Understanding that uveitis investigation may reveal systemic disease prepares owners for comprehensive testing. Being aware that chronic cases require ongoing monitoring supports long-term management. Noting any changes in eye appearance or behaviour suggestive of vision changes provides valuable information.
Last reviewed: 24 April 2026 · Dr Alastair Greenway MRCVS