Uveitis and Ocular Immunology
Core concepts
Classify uveitis by anatomy (anterior, intermediate, posterior, panuveitis), onset, and laterality. Know the classic associations: HLA-B27 anterior uveitis (ankylosing spondylitis, reactive arthritis), sarcoidosis (granulomatous, mutton-fat), Behçet (hypopyon, retinal vasculitis), toxoplasmosis (focal retinochoroiditis), and CMV (immunocompromised, sectoral iris atrophy).
Understand the immune principles: anterior chamber as an immune-privileged site, the role of T cells in non-infectious uveitis, and why steroids suppress but do not cure infection. Know when to investigate (bilateral, granulomatous, intermediate/posterior, systemic symptoms) versus treat empirically.
Traps
- Missing an infectious cause (herpes, toxoplasma, CMV) before starting steroids.
- Failing to check for systemic disease in bilateral or granulomatous uveitis.
- Confusing HLA-B27 uveitis (unilateral, recurrent, non-granulomatous) with sarcoid (bilateral, granulomatous).
- Not recognising a masquerade syndrome (lymphoma, malignancy).
Rule of thumb
Bilateral, granulomatous, or posterior/intermediate uveitis warrants systemic workup; unilateral recurrent anterior uveitis in a young adult often reflects HLA-B27 disease.
Worked example
A young man with recurrent unilateral anterior uveitis, a hypopyon, and low back pain. HLA-B27 testing and rheumatology referral are appropriate; the uveitis is treated with topical steroids and cycloplegics, and the systemic disease is managed separately.