Scleritis

Overview

Scleritis is a sight-threatening full-thickness scleral inflammation - unlike episcleritis (superficial, self-limiting). Around 50% have an underlying systemic disease. Anterior scleritis accounts for 90% of cases; posterior 10%.

Presentation

•Deep, boring eye pain - severe, aching/pressure-like; radiates to forehead, brow, jaw

•Nocturnal worsening - characteristically wakes patient from sleep

•Pain on eye movement - due to involvement of extraocular muscle insertions

•Deep red/violaceous injection - bluish tinge in natural light due to scleral thinning

•Globe tenderness - to gentle palpation over inflamed area

•Photophobia and epiphora

•Reduced visual acuity - more common in necrotising and posterior subtypes

⚠️

Scleromalacia perforans is a diagnostic trap: severe scleritis with little or no pain, occurring exclusively in longstanding RA (typically older women). A quiet white eye in severe RA should not be falsely reassuring.

Investigations

•Slit-lamp examination - assesses depth of inflammation, scleral thinning, intraocular involvement

•Phenylephrine eye drop test - blanches episcleral vessels but NOT deeper scleral vessels; persistent redness after phenylephrine confirms scleritis over episcleritis

•Systemic disease bloods - FBC, CRP, ESR, rheumatoid factor, anti-CCP, ANCA (GPA), ANA, serum uric acid

•Intraocular pressure - baseline measurement; important if steroid treatment planned

•Ocular B-scan ultrasound - for posterior scleritis; shows scleral thickening or 'T-sign' (fluid in Tenon's space)

Management

🚨

All suspected scleritis requires urgent ophthalmology referral - delays risk irreversible vision loss.

🥇 First-line

•oral NSAIDs (e.g., ibuprofen or flurbiprofen) - for mild-to-moderate anterior scleritis; use with gastroprotection

🥈 Second-line

•oral prednisolone - for NSAID-refractory or moderate-to-severe disease; topical steroids as adjunct only

•Third-line: systemic immunosuppression - necrotising scleritis, refractory disease, or underlying systemic disease driving inflammation

•Methotrexate - RA-associated disease

•Cyclophosphamide or rituximab - GPA-associated necrotising scleritis

•Infectious scleritis - targeted antimicrobials (topical and/or systemic); immunosuppression alone is contraindicated and can worsen infection

⚠️

Necrotising scleritis requires early aggressive immunosuppression - inadequate escalation risks scleral perforation.

Complications

•Scleral perforation - most feared; necrotising disease or scleromalacia perforans, especially with raised IOP

•Permanent visual loss - from perforation, retinal detachment, or optic nerve involvement (posterior scleritis)

•Anterior uveitis - occurs in up to 10% of scleritis cases

•Retinal detachment - exudative, particularly in posterior scleritis

•Glaucoma - raised IOP from chronic inflammation or steroid use

•Keratitis (sclerokeratitis) - corneal thinning/ulceration complicating necrotising scleritis

Systemic associations

•Scleritis - rheumatoid arthritis, granulomatosis with polyangiitis (GPA), other vasculitides

•Anterior uveitis - seronegative spondyloarthropathies (ankylosing spondylitis, reactive arthritis, psoriatic arthritis, IBD-related arthritis)

🎯

Do not mix up systemic associations: scleritis = RA/GPA/vasculitis; anterior uveitis = seronegative spondyloarthropathies.

Scleritis vs episcleritis

Scleritis vs episcleritis

Feature	Scleritis	Episcleritis
Pain	Deep, boring, severe; radiates; nocturnal	Mild, dull ache or none
Injection depth	Deep scleral vessels; violaceous hue	Superficial episcleral vessels; bright red
Phenylephrine test	Redness does NOT blanch	Redness blanches
Globe tenderness	Present	Absent
Visual acuity risk	Yes - sight-threatening	No
Systemic associations	Common (~50%)	Less common
Management	Urgent ophthalmology; systemic therapy	Self-limiting; topical NSAIDs/observation