Uveitis is the term for inflammation within the eye. It can affect any part of the uvea and anterior uveitis is specifically inflammation of the anterior uvea including the iris and ciliary body. The posterior uveal tissue is made up of the choroid. The term panuveitis refers to anterior and posterior uveitis, so basically uveitis in the front and back of the eye.

What do you expect to see in eyes with anterior uveitis?

Here are some clinical findings:

  • Aqueous flare
  • Miosis
  • Low intraocular pressures (initially)
  • Secondary glaucoma (chronically)
  • Hypopyon
  • Keratic precipitates
  • Corneal edema
  • Deep corneal neovascularization
  • Blepharospasm

Aqueous flare is what we use to tell us that uveitis is present. This is due to increased protein within the aqueous humor caused by breakdown of the blood-aqueous barrier when the ciliary body is inflamed. It can be difficult to tell if there is aqueous flare within an eye without knowing how to look for it. The best way is to use the slit beam on your ophthalmoscope head or the smallest focused beam you have in a dark room. Shine the light from the front and look from the side. In a normal eye, you should see the light hit the corneal surface and then you should not be able to see it within the anterior chamber as it passes through the aqueous humor. When aqueous flare is present, you will see the light travel through the anterior chamber like seeing a flashlight in fog due to the increased protein content within the aqueous humor.

What causes anterior uveitis in cats?

Here is a general list of some differentials:

  • Infectious disease
    • FeLV, FIV, FIP
    • Toxoplasmosis, Bartonella, Fungal disease
    • Really, this can be a super long list depending on where you live!
  • Neoplasia
    • Primary or secondary ocular neoplasia
  • Idiopathic/Immune-mediated
  • Trauma

How do you treat feline uveitis?

Identifying the underlying cause is the first step so that you can treat the underlying disease if present. In most cases you will need to use a topical anti-inflammatory medication such as a steroid (prednisolone acetate or dexamethasone) or a non-steroidal (ketorolac, flurbiprofen, diclofenac) to control the inflammation. Treatment for secondary glaucoma with a carbonic anhydrase inhibitor (2% Dorzolamide HCl) should be instituted if the pressure is elevated. In some cases, systemic treatment with antibiotics, antifungals, systemic anti-inflammatories, or other systemic therapies may be necessary to treat this condition. It is important to point out that topical and systemic steroids can reactive latent feline herpes virus and if the patient has a history consistent with previous herpetic ocular disease, avoiding steroids may be something to consider.

What is the prognosis for cats with uveitis?

The prognosis for vision is guarded long term and depends on the underlying cause and the ability to control the inflammation successfully. In many cats, treatment may be required long term. Many cats with chronic uveitis will develop blinding sequelae including cataract formation, lens instability/luxation, retinal detachment or degeneration, or secondary glaucoma.

The cat in this photo had lymphoma! Ocular lymphoma is the second most common type of intraocular neoplasia in cats with feline diffuse melanoma taking the lead. A 2016 study by Nerschbach et al*, noted that 48% of the cats with newly diagnosed lymphoma had ocular involvement. The WHO tumor staging guidelines classify patients with ocular lymphoma as advanced disease (stage V) due to the lack of primary lymphatic tissue within the globe. Primary ocular lymphoma does occur in people and there are reported cases of presumed solitary ocular lymphoma in cats as well.

*Nerschbach V, Eule JC, Eberle N, Höinghaus R, Betz D. Ocular manifestation of lymphoma in newly diagnosed cats. Vet Comp Oncol. 2016 Mar;14(1):58-66.