What is uveitis?
Uveitis refers to inflammation of structures within the eye and can be further classified as:
- Anterior uveitis: affecting structures in the front of the eye such as the iris
- Posterior uveitis: affecting structures in the back of the eye such as the retina
- Panuveitis: concurrent anterior and posterior uveitis
What are the clinical signs?
Acute signs include:
- Ocular redness
- Ocular pain: aversion to light, watery discharge, squinting
- A small constricted pupil
- Aqueous flare – haziness inside the eye
- Hypopyon – pus within the eye
- Reduced intra-ocular pressure
- A swollen, red iris
- Retinal oedema and detachment
- Reduced vision
Chronic signs include:
- A dark iris
- Abnormal pupil shape
- Pupil adhesions (synechiae)
- Keratic precipitates – plaques on the inside surface of the cornea
- Retinal detachment
- Blindness
What causes uveitis?
There are numerous causes of uveitis and the list of possible diagnoses is extensive. Uveitis can originate within the eye itself or represent systemic disease within the body. Generally uveitis is more likely to be infectious in origin in cats compared to dogs, however idiopathic disease (no known cause) and neoplastic disease (cancer) is also seen in both species. Immune-mediated uveitis is also common in dogs, especially those with cataract formation.
How is uveitis diagnosed?
The above clinical signs are evidence of inflammation within the eye, however the exact cause of the inflammation requires additional investigations. These initially include blood and urine samples to include screening for specific infectious agents. Imaging of the chest and abdomen may also be required, along with sampling of the fluid within the eye.
Can it be treated?
Uveitis poses a significant threat to vision thus treatment must be initiated quickly, often whilst investigations are taking place. If an exact cause is identified then the most effective therapy can be started. In many cases however despite full investigations an exact diagnosis cannot be determined. Therapy therefore aims at controlling inflammation using both systemic and topical anti-inflammatories. Ocular comfort must also be maintained thus mydriatics are advised to dilate the pupil to relieve the discomfort of spasm, and to also prevent attachments from forming. Systemic pain relief may be required if patients are in severe pain, and drops to lower the pressure inside the eye may be required if secondary glaucoma is a concern.
What is the prognosis?
The prognosis varies depending on the cause of the uveitis, the severity of the
inflammation at initial presentation and the time at which treatment was initiated. Some cases may have an initial acute episode of uveitis which resolves with minimal sequelae and does not recur. Some however have a poorer outcome and require long-term therapy to reduce ongoing inflammation and recurrence.
