Cornea and ocular surface · AO
Episcleritis and scleritis
Episclera milder · sclera more painful · no immunosuppression before infection is excluded
Last reviewed: 2026-10-06 · 潘家健醫生
Key points
- Episcleritis is usually milder; scleritis is more painful and may link to systemic inflammation.
- Necrotising scleritis or severe boring pain that wakes you: A&E now or same-day emergency eye care.
- Sudden vision drop or severe pain with headache/vomiting: A&E — do not self-label conjunctivitis.
- Do not immunosuppress before infection is excluded; post-op/trauma red pain with pus needs specialist exclusion of infection.
What it is
The episclera sits under the conjunctiva, above the sclera. Episcleritis is usually milder, often idiopathic, and many episodes are self-limiting. Scleritis is deeper, typically more painful, more often linked to systemic rheumatic or vasculitic disease, and can threaten sight. Neither is a home label for “ordinary red-eye drops”. Related uveitis is covered on the uveitis page.
How a doctor may help tell them apart (not a home drop experiment)
In clinic, phenylephrine may be used to see whether superficial vessels blanch, helping separate episcleral from deeper injection. That is an examination-room tool — this page does not instruct patients to instil phenylephrine themselves.
Anterior scleritis types (plain-language education)
- Diffuse: broader redness and tenderness
- Nodular: a local raised nodule
- Necrotising: tissue damage possible — heavier disease needing urgent specialty care
Posterior scleritis
Further back, the eye may look less red and the diagnosis is easy to miss. Pain on movement and vision change can occur. A doctor may arrange B-scan ultrasound; education sometimes mentions a “T-sign” — an imaging finding, not a DIY ultrasound.
Systemic associations (education list, not a self-ordered work-up)
Examples include rheumatoid arthritis, granulomatosis with polyangiitis (GPA) and other autoimmune or vasculitic disease. Blood tests, imaging or cross-specialty review are doctor-arranged. Infection must be excluded before immunosuppression — treating as autoimmune first can worsen untreated infection.
Treatment a specialist may discuss (classes, not a public dose table)
- Episcleritis: lubrication often first; brief oral NSAID only if a doctor advises
- Scleritis: may need systemic NSAID, corticosteroids, steroid-sparing immunosuppression, or biologics as classes — always under specialty monitoring
- No biologic or oral brand menus, and no milligram / times-daily public default schedules
After eye surgery or trauma (even months later or longer), new redness, severe pain or pus-like discharge: an ophthalmologist must exclude infection or post-operative necrotising inflammation. Do not assume “rheumatic flare” or restart leftover steroid drops. No immunosuppression until infection is excluded.
Other red eyes (do not self-match)
- Conjunctivitis, acute angle-closure glaucoma, anterior uveitis and keratitis can all be red and painful
- This page does not replace slit-lamp examination; follow the urgent page for red flags
This is general medical information, not a diagnosis, and cannot replace an in-person consultation with a registered ophthalmologist, refraction, or a dilated fundus exam. It is not advice to use any medicine or undergo any procedure. Medicines (including off-label use), laser or surgery must be decided by a registered doctor after examination, according to indications and Hong Kong registration. Figures from the literature are published averages, not any clinic’s results. This site does not book, prescribe or refer. Do not change treatment on your own.