Summary

Anterior uveitis (iritis/iridocyclitis) is inflammation of the iris and ciliary body, presenting as a painful red eye with photophobia, lacrimation, and blurred vision. It is the most common form of uveitis, accounting for 50-90% of cases. The condition is strongly associated with HLA-B27 and seronegative spondyloarthropathies (ankylosing spondylitis, reactive arthritis, psoriatic arthritis, IBD-associated arthritis). While idiopathic in ~50% of cases, systemic diseases such as sarcoidosis, Behçet's, herpes infections, and tuberculosis must be considered. Treatment requires urgent ophthalmology referral, topical corticosteroids to reduce inflammation, and cycloplegic agents to relieve pain and prevent synechiae formation.

Key Facts

• Definition: Inflammation of the iris (iritis) ± ciliary body (iridocyclitis)
• Prevalence: Most common form of uveitis; 17-52 per 100,000
• Presentation: Painful red eye, photophobia, blurred vision, lacrimation
• Classic Sign: Ciliary flush (circumcorneal limbal injection)
• Slit Lamp: Cells and flare in anterior chamber
• Key Association: HLA-B27 (50% of anterior uveitis; 90% of AS-related uveitis)
• Key Management: Urgent ophthalmology; topical steroids + cycloplegics

Clinical Pearls

"Painful Red Eye with Photophobia = Think Uveitis": Unlike conjunctivitis (gritty, no photophobia, no visual loss) or episcleritis (localised, minimal pain), anterior uveitis causes deep aching pain, consensual photophobia, and vision changes.

Consensual Photophobia: Shining light in the UNAFFECTED eye causes pain in the AFFECTED eye. This is diagnostic of anterior uveitis — ciliary spasm is triggered bilaterally.

HLA-B27 Link: Up to 50% of anterior uveitis is HLA-B27 positive. Ask about back pain, stiffness, joint symptoms.

Why This Matters Clinically

Anterior uveitis requires prompt recognition and treatment to prevent complications such as posterior synechiae (iris adhesion to lens), glaucoma, cataract, and permanent visual loss. Recurrent episodes are common. Many cases indicate underlying systemic disease, making appropriate investigation important.

Structured Approach

General Inspection:

• Red eye with circumcorneal (limbal) injection
• Photophobia on examination
• May be tearing

Visual Acuity:

• Document before and after dilation
• May be reduced (usually mild unless complications)

Pupil Examination:

• Miosis (small, reactive)
• Irregular if posterior synechiae present
• Test consensual photophobia (light in unaffected eye → pain in affected eye)

Slit Lamp Examination (Key):

Intraocular Pressure (IOP):

• May be low (ciliary shutdown) or high (trabecular obstruction)

Fundoscopy:

• Rule out posterior segment involvement
• Vitritis suggests intermediate/posterior uveitis

Special Tests

Natural History

Acute anterior uveitis typically resolves within weeks with appropriate treatment. However, recurrence is common (40-50%), particularly in HLA-B27 positive patients. Chronic or recurrent cases may develop complications leading to permanent visual impairment.

Outcomes

Prognostic Factors

Good Prognosis:

• First episode
• Acute presentation
• Good response to topical steroids
• No synechiae
• No underlying chronic disease

Poor Prognosis:

• Recurrent episodes
• HLA-B27 positive (more recurrences)
• Granulomatous uveitis
• Posterior involvement
• Systemic disease (Behçet's, JIA)
• Complications present at diagnosis

Key Guidelines

1. NICE CKS: Red Eye (2023) — Primary care guidance on referral and initial management.
2. American Academy of Ophthalmology Uveitis Preferred Practice Pattern (2019) — Comprehensive specialist guidance.
3. British Society for Rheumatology HLA-B27 SpA Guidelines — Management of associated spondyloarthropathy.

Key Studies

Adalimumab for Uveitis (VISUAL 1 & 2 Trials, 2016) — Adalimumab effective for non-infectious intermediate, posterior, and panuveitis.

• PMID: 27457817

Evidence Strength

What is Anterior Uveitis?

Anterior uveitis is inflammation inside the front part of the eye, affecting the iris (the coloured part) and the ciliary body (which focuses the lens). It causes a painful, red eye with sensitivity to light and blurred vision. It is sometimes called "iritis."

Why does it happen?

• In about half of cases, no specific cause is found
• It's often linked to a gene called HLA-B27, which is also associated with types of arthritis affecting the spine
• Infections (herpes, tuberculosis) and other inflammatory conditions (sarcoidosis, Behçet's) can cause it
• It can keep coming back, especially if you have HLA-B27

How is it treated?

1. Eye drops: Steroid drops to reduce inflammation (used frequently at first, then tapered slowly)
2. Dilating drops: To relieve pain and prevent the iris from sticking to the lens
3. Follow-up: Regular eye checks until inflammation clears and drops are stopped
4. Investigation: If it keeps coming back, blood tests and X-rays may be needed to look for underlying causes

What to expect

• Most episodes clear up within a few weeks with treatment
• It can come back — 40-50% of people have another episode
• If you have HLA-B27 or a related condition, recurrences are more likely
• Stopping drops too quickly can cause the inflammation to return

When to seek help

• If you have a painful red eye with sensitivity to light — see a doctor the same day
• If your vision gets worse
• If you see a white layer at the bottom of your eye (hypopyon)
• If you have back pain or joint stiffness (may indicate underlying arthritis)