Anterior Uveitis
Definition
Inflammation of the anterior uveal tract (iris and ciliary body), the most common form of uveitis, characterized by anterior chamber cells and flare, keratic precipitates, and variable degrees of photophobia and pain.
Clinical Snapshot
Anterior uveitis (AU) — also termed iritis or iridocyclitis — is the most common form of uveitis, accounting for approximately 75% of all uveitis cases. It is defined by inflammation of the iris and/or ciliary body, with cells and flare in the anterior chamber as the hallmark finding. The majority of cases are idiopathic or HLA-B27–associated. Recurrent AU in a young adult should prompt systemic evaluation for HLA-B27–associated spondyloarthropathies. Prompt treatment with topical corticosteroids and cycloplegics prevents complications including posterior synechiae, cataract, and secondary glaucoma.
Epidemiology
AU has an annual incidence of approximately 8–12 per 100,000 and a prevalence of approximately 69 per 100,000. It is the most common form of uveitis in developed countries. HLA-B27 is present in approximately 50% of patients with recurrent AU, compared to approximately 8% of the general population.
Pathophysiology
AU results from breakdown of the blood-aqueous barrier, allowing inflammatory cells and protein (flare) to enter the anterior chamber. In HLA-B27–associated AU, molecular mimicry between bacterial antigens (particularly Klebsiella pneumoniae) and HLA-B27 is hypothesized to trigger the autoimmune response. Granulomatous AU (large "mutton-fat" KPs) is associated with sarcoidosis, VKH, and sympathetic ophthalmia. Non-granulomatous AU (fine KPs) is associated with HLA-B27 spondyloarthropathies and herpetic disease.
Risk Factors
- HLA-B27 positivity (the strongest genetic risk factor)
- Ankylosing spondylitis (25–40% develop AU)
- Reactive arthritis (formerly Reiter's syndrome)
- Inflammatory bowel disease (Crohn's, ulcerative colitis)
- Psoriatic arthritis
- Herpetic infection (HSV, VZV, CMV)
- Juvenile idiopathic arthritis (JIA — particularly ANA-positive oligoarticular)
Clinical Presentation
Acute onset of unilateral photophobia, pain, and blurred vision. Circumlimbal (ciliary) injection. Slit lamp: anterior chamber cells (graded 0–4+) and flare (protein), keratic precipitates (KPs) on the corneal endothelium, posterior synechiae (iris adhesions to the anterior lens capsule). Hypopyon in severe cases. IOP may be elevated (trabeculitis) or reduced (ciliary body shutdown).
Diagnostic Pearls
- Grade anterior chamber cells (0–4+) at every visit — it is the primary measure of disease activity and treatment response.
- Distinguish granulomatous (large mutton-fat KPs, iris nodules — Koeppe/Busacca) from non-granulomatous (fine stellate KPs) AU — the distinction guides the systemic workup.
- HLA-B27 testing is appropriate for recurrent or bilateral AU — a positive result warrants rheumatology referral.
- CMV anterior uveitis (Posner-Schlossman syndrome) presents with recurrent unilateral elevated IOP and minimal AC reaction — consider CMV PCR of aqueous humor.
Differential Diagnosis
- Acute angle-closure glaucoma (elevated IOP, corneal edema, mid-dilated pupil)
- Herpetic keratouveitis (corneal involvement, elevated IOP)
- Fuchs heterochromic iridocyclitis (heterochromia, stellate KPs, no synechiae)
- Masquerade syndromes (lymphoma — particularly in older patients)
Evidence-Based Management
Topical corticosteroids: prednisolone acetate 1% (Pred Forte®) — frequency titrated to cell grade (hourly for severe, QID for mild). Cycloplegics: cyclopentolate 1% or homatropine 5% — reduce pain, prevent posterior synechiae, and stabilize the blood-aqueous barrier. Taper corticosteroids slowly based on cell resolution — premature taper is the most common cause of recurrence. Periocular or systemic corticosteroids for severe or refractory cases. Systemic immunosuppression (methotrexate, mycophenolate) for chronic or recurrent disease.
Monitoring & Follow-Up
Follow up every 1–2 weeks during active inflammation. Monitor IOP at every visit — both corticosteroid-induced elevation and hypotony from ciliary body shutdown are possible. Dilated examination to assess for posterior synechiae, cataract, and CME.
Clinical Pearls
- Taper corticosteroids slowly — premature taper is the most common cause of recurrence and the leading reason for chronic disease.
- HLA-B27–associated AU is typically acute, unilateral, and recurrent — the fellow eye is often involved in subsequent episodes.
- Monitor IOP at every visit — corticosteroid-induced glaucoma is a significant complication of prolonged topical steroid use.
- JIA-associated uveitis is typically chronic, asymptomatic, and bilateral — it requires regular slit lamp screening even in the absence of symptoms.
Related Therapeutics — Clinician's Companion
- Anti-inflammatory Rescue — Pred Forte®, Durezol® (Clinician's Companion)
- Oral Therapeutics — Oral Prednisone, Methotrexate (Clinician's Companion)
Key References
- 1.Rosenbaum JT. Uveitis: an internist's view. Arch Intern Med. 1989.
- 2.Jabs DA, et al. Standardization of uveitis nomenclature for reporting clinical data. Am J Ophthalmol. 2005.
This entry is an educational reference designed to support clinical reasoning and awareness. It does not constitute medical advice, establish a standard of care, or replace individualized patient assessment. Clinicians should consult current guidelines and applicable clinical resources when making patient care decisions.