Episcleritis and Scleritis
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Episcleritis is a benign, self limiting inflammation of the episclera, the thin layer of connective tissue between the conjunctiva and sclera. Scleritis is a more severe, potentially sight threatening inflammation of the sclera, often associated with systemic autoimmune diseases.
Aetiology
- Episcleritis: idiopathic in most cases, but may be associated with systemic inflammatory conditions such as rheumatoid arthritis, lupus, or inflammatory bowel disease.
- Scleritis: commonly linked to systemic autoimmune disorders (e.g., rheumatoid arthritis, granulomatosis with polyangiitis, relapsing polychondritis).
- Infectious causes (less common): herpes zoster, tuberculosis, syphilis.
Pathophysiology
- Episcleritis involves localized inflammation of the episclera without significant scleral involvement.
- Scleritis is a deeper inflammatory process affecting the scleral blood vessels, potentially leading to necrosis and thinning of the sclera.
- Immune complex deposition and activation of inflammatory pathways contribute to scleral damage.
Risk Factors
- Systemic autoimmune diseases (e.g., rheumatoid arthritis, systemic lupus erythematosus).
- Previous episodes of episcleritis or scleritis.
- Infectious causes (e.g., herpes zoster, tuberculosis).
- Ocular surgery or trauma.
Signs and Symptoms
- Episcleritis: mild discomfort, sectoral redness, no significant pain or visual disturbance.
- Scleritis: severe, boring eye pain, diffuse or nodular redness, photophobia, tearing.
- In posterior scleritis, symptoms may include decreased vision, proptosis, and pain with eye movement.
Investigations
- Slit-lamp examination: assesses extent of inflammation and distinguishes episcleritis from scleritis.
- Fundoscopy: evaluates for posterior scleritis.
- Blood tests: autoimmune screen (ANA, RF, ANCA), ESR/CRP to assess systemic inflammation.
Management
1. Episcleritis:
- Supportive care: cold compresses, lubricating eye drops.
- Topical NSAIDs: for symptomatic relief.
- Oral NSAIDs: in more persistent cases.
2. Scleritis:
- Oral NSAIDs: first line for mild cases.
- Systemic corticosteroids: for moderate to severe cases.
- Immunosuppressive therapy: methotrexate, azathioprine, or biologics in refractory cases.
- Antibiotics or antivirals: if an infectious cause is identified.
3. Referral:
- Ophthalmology: all cases of suspected scleritis require urgent referral.
- Rheumatology: for autoimmune-associated scleritis.
- Infectious diseases: if an infectious aetiology is suspected.