Uveitis
Inflammation of the uvea, an ophthalmic emergency that can cause blindness.
Uveitis is inflammation of the uvea, the pigmented middle layer of the eye that includes the iris, ciliary body, and choroid. It is an ophthalmic emergency requiring urgent control to prevent vision loss, and in the United States it accounts for about 10–20% of cases of blindness. Uveitis is described anatomically as anterior, intermediate, posterior, or panuveitic, with anterior uveitis being the most common form.
Quick Facts
- Pronounce
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- Field
- Ophthalmology, optometry
- Complications
- Cataract
- Glaucoma
- Uveitic Macular edema
- Band Keratopathy
- Types
- Anterior uveitis
- Intermediate uveitis
- Posterior uveitis or Panuveitis
Facts from the source article.
Signs and symptoms
The disease course, anatomy, and laterality vary widely. Cases may be acute (sudden onset, less than three months duration) and monophonic, acute and recurrent, or chronic. Symptoms include eye pain, redness, blurred vision, photophobia, irregular pupil, and floaters. Anterior uveitis signs include dilated ciliary vessels, cells and flare in the anterior chamber, keratic precipitates on the posterior cornea, and in severe cases a hypopyon. Busacca nodules may appear on the iris in granulomatous forms. Synechiae—adhesions of the iris to the cornea or lens—can occur. Intermediate uveitis usually affects one eye, with floaters and blurred vision more common than pain. Posterior uveitis features floaters and blurred vision.
Causes
Uveitis is usually an isolated illness but can be associated with many conditions. In about half of anterior uveitis cases, no associated syndrome is found. Acute anterior uveitis is most commonly associated with HLA-B27, which has a relative risk of approximately 15%. HLA-B27-positive AAU shows male preponderance, unilateral alternating acute onset, non-granulomatous appearance, and frequent recurrences; HLA-B27-negative AAU has equal male-to-female onset, bilateral chronic course, and more frequent granulomatous appearance. Associated systemic disorders include spondyloarthritis, ankylosing spondylitis, juvenile idiopathic arthritis, sarcoidosis, Behçet disease, inflammatory bowel disease, multiple sclerosis, and Vogt–Koyanagi–Harada disease. Infectious causes include bartonellosis, tuberculosis, herpes simplex, herpes zoster ophthalmicus, syphilis, toxoplasmosis, and Lyme disease. Rifabutin and quinolones such as moxifloxacin may also cause uveitis.
Pathophysiology
Uveitis results from a failure of the ocular immune system, driven by Th17 T cells specific for ocular proteins. Autoreactive T cells are normally suppressed by microglia and dendritic cells producing TGF beta and IL-10, which promote inducible Treg cells. Innate immune stimulation is suppressed by myeloid suppression, while inducible Treg cells prevent activation of autoreactive Th1 and Th17 cells. Disruption of this balance allows autoreactive T cells to proliferate and migrate to the eye. Failure of re-induction of Treg cells leads to neutrophil and leukocyte recruitment via IL-17 secretion. Tissue destruction is mediated by non-specific macrophage activation and cytokine cascades. Serum TNF-α is significantly elevated, while IL-6 and IL-8 are higher in the aqueous humour in both quiescent and active uveitis. Genetic factors include HLA-B27 and PTPN22. Reactivation of herpes simplex, varicella zoster, and other viruses, as well as bacterial infection, are important contributing factors.
Treatment
Uveitis is typically treated with glucocorticoid steroids, either as topical eye drops (prednisolone acetate) or oral therapy. Corneal ulcers must be ruled out with a fluorescence dye test before corticosteroids. Topical cycloplegics such as atropine or homatropine may be used. In severe cases, posterior subtenon triamcinolone acetate injection may reduce swelling. Intravitreal injection of dexamethasone or fluocinolone acetonide provides longer control. Non-biologic steroid-sparing therapies include methotrexate, mycophenolate, cyclosporine, azathioprine, and tacrolimus; methotrexate is more efficacious than mycophenolate for most panuveitis. Biologic agents such as adalimumab, a TNF-α blocker approved for non-infectious intermediate, posterior, and panuveitis, extend time to treatment failure and reduce failure rates. Other TNF inhibitors like infliximab show efficacy, and JAK inhibitors are under investigation. For herpetic uveitis, antiviral medications such as valaciclovir or aciclovir are used.
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