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OP5.1-2 | Sclera — Practice Quiz
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A 28-year-old woman presents with a mild, aching red eye of two days duration. She reports minimal watering and no significant pain. On slit-lamp examination there is sectoral bright-red injection of the superficial episcleral vessels. After instillation of phenylephrine 2.5%, the redness blanches completely within 90 seconds. What is the most likely diagnosis?
Correct. Complete blanching with phenylephrine 2.5% distinguishes episcleritis from scleritis. Episcleritis is superficial, self-limiting, and causes mild discomfort rather than severe pain.
Complete blanching with phenylephrine 2.5% is the hallmark of episcleritis, confirming that the inflamed vessels are superficial episcleral vessels (not deep scleral). Scleritis does not blanch.
Incorrect. The key finding here is complete blanching with phenylephrine 2.5%, which is diagnostic of episcleritis. Scleritis does not blanch because the inflamed vessels are in the deep scleral plexus, beyond the reach of topical vasoconstrictors.
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A 45-year-old man with known rheumatoid arthritis presents with severe, boring eye pain radiating to the temple and jaw, waking him from sleep. The eye is diffusely red with a violaceous hue. Instillation of phenylephrine 2.5% does not reduce the redness. Which Watson-Hayreh classification best describes this presentation?
Correct. Diffuse anterior scleritis presents with generalised scleral injection (violaceous hue), severe boring pain unresponsive to phenylephrine, and is commonly associated with rheumatoid arthritis.
The Watson-Hayreh classification distinguishes episcleritis (simple/nodular) from scleritis (anterior: diffuse/nodular/necrotising; posterior). Diffuse anterior scleritis is the most common form of scleritis, presenting with violaceous hue, severe pain, and non-blanching injection.
Incorrect. The violaceous hue, severe boring pain, failure to blanch with phenylephrine, and systemic RA point to diffuse anterior scleritis — the most common subtype of scleritis in the Watson-Hayreh classification.
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Which of the following best explains why episcleritis blanches with phenylephrine 2.5% but scleritis does not?
Correct. Topical phenylephrine 2.5% vasoconstricts the superficial episcleral vessels (episcleritis) but cannot penetrate to the deep scleral vascular plexus (scleritis), making blanching a reliable differentiating test.
The anatomical basis of the phenylephrine blanching test: superficial episcleral vessels are accessible to topical vasoconstrictors; the deep scleral plexus involved in scleritis is not.
Incorrect. The blanching test works because of anatomical depth: episcleral vessels are superficial and respond to topical vasoconstrictors, while the deep scleral plexus affected in scleritis does not.
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A 38-year-old woman with no known systemic illness is diagnosed with diffuse anterior scleritis. Which single investigation is most urgently indicated in her systemic work-up?
Correct. Every new scleritis patient requires systemic work-up for connective tissue disease or vasculitis. ANA (SLE), ANCA (GPA), RF (RA), ESR, and urine microscopy (haematuria in GPA nephritis) are the core first-line panel.
Approximately 50% of scleritis patients have an identifiable systemic disease — most commonly rheumatoid arthritis, granulomatosis with polyangiitis (GPA/Wegener), or other vasculitides. A minimum work-up includes ANA, ANCA, RF, ESR/CRP, and urine microscopy (ANCA + haematuria = urgent nephrology referral for GPA).
Incorrect. Scleritis is associated with systemic connective tissue or vasculitic disease in approximately 50% of cases. The minimum work-up includes ANA, ANCA, RF, ESR, and critically urine microscopy — haematuria in an ANCA-positive patient signals GPA nephritis requiring urgent referral.
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A patient with episcleritis experiences significant discomfort. What is the most appropriate first-line pharmacological treatment?
Correct. Management of episcleritis begins with the least invasive option: lubricants and cool compresses. Oral NSAIDs are added if discomfort persists. Systemic steroids are reserved for scleritis, not episcleritis.
Episcleritis is self-limiting in most patients within 2-3 weeks. First-line treatment is symptomatic: cool compresses and topical lubricants. If discomfort is significant, oral NSAIDs (ibuprofen/flurbiprofen) are added. Systemic steroids are not warranted for episcleritis.
Incorrect. Episcleritis is self-limiting and does not require systemic steroids. The stepwise approach is: lubricants first, oral NSAIDs if needed. Reserve stronger immunosuppression for scleritis, particularly necrotising scleritis with systemic disease.
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Which systemic condition is MOST strongly associated with necrotising scleritis?
Correct. Both RA and GPA are strongly associated with scleritis. GPA (formerly Wegener) is particularly dangerous because concurrent glomerulonephritis can be life-threatening; positive ANCA with haematuria mandates urgent systemic referral.
Necrotising scleritis (with or without inflammation — scleromalacia perforans) is most strongly linked to rheumatoid arthritis and GPA. GPA carries the highest systemic risk because coexisting glomerulonephritis is life-threatening and ANCA testing is mandatory.
Incorrect. Diabetes is not significantly associated with scleritis. The key systemic associations are rheumatoid arthritis (most common) and GPA (most dangerous — systemic vasculitis with renal involvement). ANCA testing is mandatory in all new scleritis patients.
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