Scleral Disorders: Episcleritis, Scleritis, Scleral Thinning and Emergencies

Scope. The sclera is the tough, collagen-rich outer coat of the eye. Inflammation may be superficial and self-limiting (episcleritis), or deep, destructive and vision-threatening (scleritis). The two can look similar at first glance, but their pain, colour, vessel pattern, systemic associations, complications and treatment are very different. This resource expands the supplied teaching slides into a practical guide for emergency medicine and ophthalmology learners.

Learning objectives

• Describe scleral anatomy, blood supply and the relationship between sclera, episclera, conjunctiva, cornea and uvea.
• Differentiate episcleritis from scleritis and from conjunctivitis, keratitis, uveitis and acute glaucoma.
• Classify anterior, posterior, diffuse, nodular, necrotising and infectious scleritis.
• Recognise systemic inflammatory, infectious, traumatic, postoperative and drug-related causes.
• Perform a safe assessment, choose focused investigations and begin appropriate emergency management and referral.
• Anticipate complications such as keratitis, uveitis, glaucoma, cataract, retinal detachment, scleral melt and perforation.

1. Anatomy and physiology of the sclera

The sclera forms approximately the posterior five-sixths of the fibrous coat of the globe. It is continuous anteriorly with the cornea at the limbus and posteriorly with the dura surrounding the optic nerve. Its dense, irregular type-I collagen gives the eye shape and protects the intraocular contents while allowing the extraocular muscles to insert and move the globe.

Although the sclera itself has relatively few vessels, inflammation recruits deep and superficial vascular networks. This explains why the eye can appear intensely red even when the primary pathology is not conjunctival. The posterior sclera lies close to the choroid, retina, optic nerve and extraocular muscles, so posterior inflammation can reduce vision without an obvious anterior red eye.

2. A safe approach to the painful red eye

2.1 History

• Onset and course: sudden, progressive, recurrent, migratory or chronic symptoms; ask about previous episodes and the duration of pain before redness.
• Pain quality: deep boring or aching orbital pain, pain radiating to the face or temple, pain on eye movement and night pain favour scleritis. Mild irritation and tenderness favour episcleritis.
• Vision: ask about blur, field loss, floaters, flashes, halos, colour desaturation and diplopia. Any new reduction is a red flag.
• Photophobia and discharge: prominent photophobia suggests corneal or uveal involvement; watery discharge may accompany scleritis, while purulent discharge suggests infection.
• Systemic inflammatory symptoms: joint pain or morning stiffness, back pain, psoriasis, inflammatory bowel disease, painful ears or nose, oral/genital ulcers, sinus disease, cough, haematuria, skin purpura and neuropathy.
• Infection and exposure: tuberculosis, syphilis, herpes zoster, fungal infection, recent respiratory or skin infection, bites, contaminated water, surgery, injections and penetrating trauma.
• Medication history: bisphosphonates, topical glaucoma medicines, immune-checkpoint inhibitors, anticoagulants and recent corticosteroid withdrawal; ask about allergy and immunosuppression.
• Trauma/operation: previous pterygium or cataract surgery, scleral buckle, foreign body, chemical burn or recent intraocular procedure can predispose to infectious or necrotising disease.

2.2 Examination sequence

1. Assess general condition, temperature, facial rash, ear/nose cartilage, joint swelling and signs of systemic vasculitis.
2. Measure visual acuity in each eye separately with correction and pinhole. Record the baseline before treatment.
3. Inspect pupils, colour vision if available, and check for a relative afferent pupillary defect.
4. Assess ocular motility, pain on movement, diplopia, proptosis and restriction, which may indicate posterior scleritis or orbital disease.
5. Compare the hue and distribution of injection. Episcleral vessels are bright red or salmon-pink and often sectoral; scleritis is deeper, diffuse or nodular and violaceous.
6. Observe whether vessels move with a cotton bud and whether superficial vessels blanch with a clinician-administered vasoconstrictor test. Never delay referral or use a test as a substitute for slit-lamp examination.
7. Examine the cornea with fluorescein for ulcer, infiltrate, thinning, melt or a Seidel leak. Do not press on a suspected perforation or severely thinned sclera.
8. Examine the anterior chamber for cells, flare, hypopyon and fibrin; examine the lens, vitreous and fundus when possible.
9. Measure intraocular pressure only after an open globe has been excluded and when the examination is safe.
10. Palpate the globe gently only if there is no concern for perforation; document focal tenderness, nodules, scleral thinning and areas of translucency.

3. Episcleritis

Episcleritis is inflammation of the superficial episcleral tissue. It usually affects young or middle-aged adults, is often idiopathic and frequently recurs. It can be associated with rheumatoid arthritis, inflammatory bowel disease, systemic lupus, gout, rosacea, vasculitis and other immune conditions, but most patients do not have a serious systemic illness.

3.1 Clinical patterns

Visual acuity and the cornea are usually normal. Severe pain, pain on movement, marked photophobia, scleral tenderness or reduced vision should make the diagnosis of uncomplicated episcleritis doubtful.

3.2 Management principles

• Explain that uncomplicated episcleritis is usually self-limiting and does not destroy the eye.
• Use cool compresses, preservative-free lubricants and avoidance of smoke, dust, wind and eye rubbing.
• If symptoms are significant or persistent, a clinician may use an oral non-steroidal anti-inflammatory drug after checking renal disease, peptic ulcer risk, asthma, pregnancy, anticoagulants and other contraindications.
• Topical corticosteroids should be prescribed and monitored by an eye clinician when needed; they can raise intraocular pressure, reactivate herpes and worsen infection.
• Investigate recurrent, bilateral, nodular, atypical or severe disease for systemic inflammatory illness or infection.
• Arrange review if it does not improve, recurs frequently, develops pain or vision change, or does not blanch as expected.

4. Scleritis

Scleritis is severe inflammation of the deep episclera and sclera. It is destructive and may cause scleral thinning, keratitis, uveitis, glaucoma, cataract, retinal complications and permanent loss of vision. Approximately one-half of patients have an associated systemic inflammatory disease, although infection and idiopathic disease also occur.

4.1 Anterior scleritis

Anterior scleritis is visible at the front of the eye. The redness is deep red to violaceous and does not behave like superficial conjunctival injection. Pain is often severe, boring and worse at night or with eye movement. Tearing, photophobia, headache and reduced acuity may develop when the cornea, uvea or optic nerve is involved.

4.2 Posterior scleritis

Posterior scleritis involves the sclera behind the equator and may have little external redness. It can cause deep orbital pain, headache, pain on movement, blurred vision, choroidal folds, optic-disc swelling, exudative retinal detachment, vitreous inflammation, proptosis or restricted motility. It may be mistaken for orbital cellulitis, optic neuritis, uveal effusion, choroidal tumour or acute angle-closure glaucoma. B-scan ultrasonography and specialist imaging are often required.

4.3 Infectious scleritis

Infectious scleritis may follow surgery, trauma, foreign-body implantation or contiguous infection. Bacteria, fungi, herpes viruses and parasites can be responsible. Severe focal pain, purulent material, scleral necrosis, an abscess, immunosuppression or failure to respond to anti-inflammatory therapy should raise suspicion. Immunosuppression without excluding infection can accelerate tissue destruction.

5. Causes and systemic associations

6. Differentiating common causes of a red eye

7. Investigations

Investigations are guided by severity, recurrence, laterality and systemic findings. A mild first episode of typical episcleritis may not require extensive testing; severe or recurrent disease does.

• Ocular tests: visual acuity, slit-lamp examination, fluorescein staining, anterior chamber assessment, intraocular pressure when safe, dilated fundus examination and B-scan ultrasonography for suspected posterior scleritis.
• Inflammation and blood: full blood count, ESR or CRP, renal and liver profile, urinalysis and blood pressure; these help identify systemic inflammation or vasculitis.
• Autoimmune testing: rheumatoid factor, anti-CCP, ANA, ANCA, HLA-B27 and other tests selected by symptoms. A positive result is not a diagnosis without clinical correlation.
• Infection testing: syphilis serology, HIV testing with consent, tuberculosis evaluation, herpes testing where appropriate, blood cultures or scleral/corneal samples when infection is suspected.
• Imaging: orbital CT/MRI if proptosis, restricted movement, trauma, abscess or posterior disease is suspected; chest imaging when sarcoidosis, TB or vasculitis is considered.

8. Management

8.1 Immediate and first-contact care

1. Check acuity, pupils and vital signs; treat the patient as urgent if vision is reduced or pain is severe.
2. Remove contact lenses and stop non-essential topical medicines that may be irritating, while preserving prescribed systemic therapy.
3. Use a clean protective shield if trauma or globe weakness is possible; do not patch a suspected infectious ulcer or open globe.
4. Do not rub, press, massage or apply traditional substances to the eye.
5. Provide analgesia appropriate to the patient while arranging examination and referral. Avoid self-prescribing corticosteroids or steroid-combination drops.
6. If a chemical injury is possible, irrigate immediately and continue until ocular surface pH is neutral; referral must not be delayed.

8.2 Episcleritis treatment

• Reassurance, cool compresses, lubricants and avoidance of triggers for mild disease.
• Clinician-selected oral NSAID when needed, after checking gastrointestinal, renal, cardiovascular, respiratory, pregnancy and anticoagulant risks.
• Specialist-supervised topical steroid for selected persistent inflammation, with monitoring for pressure rise, cataract and infection.
• Treat an identified systemic disorder in collaboration with the appropriate physician; repeated episodes warrant follow-up.

8.3 Scleritis treatment

Scleritis normally requires systemic therapy directed by an ophthalmologist, often with rheumatology or infectious-disease input. Treatment is selected according to whether the process is immune-mediated or infectious, the subtype, comorbidities and organ-threatening disease.

• Non-infectious disease: systemic anti-inflammatory therapy may begin with an NSAID in selected mild cases; corticosteroids or steroid-sparing immunomodulators are used for severe, necrotising, recurrent or refractory disease.
• Refractory immune disease: agents such as methotrexate, mycophenolate, azathioprine, cyclophosphamide or biologic therapy may be chosen by a specialist based on the underlying systemic diagnosis and monitoring requirements.
• Infectious disease: obtain cultures or tissue when feasible and give targeted antimicrobial treatment. Avoid immunosuppression until infection is considered and covered.
• Complications: treat uveitis, glaucoma, cataract, keratitis, raised pressure, retinal detachment or optic-nerve involvement urgently. Scleral grafting or tectonic surgery may be needed for impending or established perforation.
• Follow-up: review pain, acuity, colour, injection, scleral thickness, intraocular pressure and systemic disease activity. Taper corticosteroids only under the treating clinician’s plan.

9. Complications

• Ocular surface: peripheral ulcerative keratitis, corneal melt, thinning, perforation and irregular astigmatism.
• Anterior segment: anterior uveitis, posterior synechiae, secondary glaucoma, hypotony and cataract.
• Posterior segment: choroidal folds, exudative retinal detachment, optic-disc oedema, macular distortion and vision loss.
• Structural: scleral thinning, ectasia, staphyloma and spontaneous rupture after minor trauma.
• Systemic: untreated vasculitis, renal injury, pulmonary haemorrhage, cartilage destruction or other organ-threatening disease.

10. Nursing and emergency-care responsibilities

• Record pain score, acuity, pupil findings, colour and the exact area of injection at each contact.
• Use strict hand hygiene and avoid contaminated dropper tips; do not share eye medicines.
• Check adherence, adverse effects, blood pressure, blood glucose and laboratory monitoring when systemic steroids or immunosuppressants are prescribed.
• Screen for fever, cough, urinary changes, joint symptoms, skin lesions and medication toxicity; escalate new systemic features.
• Teach the patient to return immediately for worsening pain, new blur, flashes/floaters, photophobia, discharge, a white patch, increasing redness or trauma.
• Coordinate ophthalmology, rheumatology, infectious-disease and emergency referrals; record referral time and handover information.

11. Applied cases

Case 1: Mild sectoral redness

A 27-year-old has recurrent sectoral bright-red redness, mild tenderness, normal acuity and no photophobia or corneal staining. The likely diagnosis is simple episcleritis. Provide reassurance, cool compresses and lubricants, review triggers and arrange review if it persists, recurs frequently or develops pain/vision change.

Case 2: Deep night pain with a violaceous hue

A 42-year-old with rheumatoid arthritis reports severe deep eye pain worse at night and on movement. The redness is diffuse and violaceous and acuity is slightly reduced. This is probable anterior scleritis, not conjunctivitis. Protect the eye, assess the cornea and anterior chamber, avoid unsupervised steroid drops and arrange same-day ophthalmology and systemic assessment.

Case 3: Quiet but dangerously thin sclera

A patient with long-standing rheumatoid arthritis has a painless grey-yellow area where the sclera appears thin. This suggests scleromalacia perforans. The absence of pain does not make it safe. Avoid pressure and tonometry until assessed, protect from trauma and urgently refer for ophthalmic and rheumatologic care.

Case 4: Pain after eye surgery

Two weeks after pterygium surgery, a patient develops focal pain, discharge and a necrotic scleral patch. Infectious scleritis must be considered. Take appropriate samples, involve ophthalmology urgently and avoid treating it as routine immune scleritis without antimicrobial evaluation.

Case 5: No obvious red eye but severe orbital pain

A patient has deep pain, blurred vision, pain on movement and a quiet anterior eye. Posterior scleritis is possible. Arrange urgent specialist imaging, including B-scan ultrasonography where available, and do not dismiss the complaint because the conjunctiva is not dramatically red.

12. Self-test

1. What is the key difference between episcleritis and scleritis?
2. Name four red flags in a painful red eye.
3. Which scleritis subtype can be painless yet cause severe scleral thinning?
4. Why is posterior scleritis easy to miss?
5. Name three systemic diseases associated with scleritis.
6. Why must infection be considered before immunosuppression?
7. When is intraocular pressure measurement unsafe?
8. What complications can arise from necrotising scleritis?

Answers

1. Episcleritis is superficial, usually mild and self-limiting; scleritis is deep, severely painful, destructive and potentially vision-threatening.
2. Examples include severe deep pain, pain on movement, reduced vision, photophobia, corneal ulcer/thinning, hypopyon, proptosis, necrotising/violaceous sclera, recent surgery or trauma, and immunosuppression.
3. Necrotising scleritis without inflammation, also called scleromalacia perforans.
4. It affects the posterior sclera, so the front of the eye may look nearly normal; symptoms may resemble orbital or retinal disease.
5. Rheumatoid arthritis, granulomatosis with polyangiitis, relapsing polychondritis, systemic lupus, inflammatory bowel disease and ankylosing spondylitis are examples.
6. Steroids and immunosuppressants can accelerate bacterial, fungal or viral tissue destruction and cause perforation.
7. When an open globe, severe scleral thinning, penetrating injury or perforation has not been excluded.
8. Scleral melt, corneal melt, perforation, uveitis, glaucoma, retinal complications and permanent visual loss.

Key takeaways

• Bright-red mild sectoral inflammation suggests episcleritis; deep violaceous redness and severe pain suggest scleritis.
• Normal external appearance does not exclude posterior scleritis.
• Scleritis is frequently associated with systemic inflammatory disease and may be the first sign of organ-threatening vasculitis.
• Infectious, postoperative and traumatic disease must be separated from immune-mediated disease before immunosuppression.
• A painful red eye with reduced vision or corneal/scleral thinning is an emergency.

References and further reading

• Supplied teaching slides: Diseases of the Sclera.
• EyeWiki: Episcleritis.
• EyeWiki: Scleritis.
• Merck Manual Professional: Scleritis.
• Merck Manual Professional: Episcleritis.
• Uganda Ministry of Health: Guidelines for Eye Care.