Describe peripheral ulcerative keratitis and Mooren ulcer.

Peripheral Ulcerative Keratitis

• Why the periphery — the peripheral cornea is close to the limbal vessels, and therefore has access to immune complexes, complement, immunoglobulin and inflammatory cells that the avascular centre does not; and it contains Langerhans cells. This anatomy explains why immunological corneal disease is peripheral and infective disease is central
• Systemic associations — and the crucial point is that PUK may be the presenting feature of a life-threatening vasculitis: rheumatoid arthritis (the commonest association); granulomatosis with polyangiitis (Wegener), in which PUK with scleritis is classical and mortality without treatment is high; polyarteritis nodosa; systemic lupus erythematosus; relapsing polychondritis; and inflammatory bowel disease

Mooren’s Ulcer

• MOOREN’S ulcer is a painful, progressive, chronic peripheral ulcerative keratitis of unknown cause, and is a diagnosis OF exclusion — made only after systemic vasculitis and infection have been excluded. There is NO associated scleritis, which is a useful distinguishing feature
• Characteristic appearance — a crescentic ulcer beginning peripherally and spreading circumferentially and then centrally, with a characteristically overhanging, undermined leading edge; the base vascularises and thins; and it may involve the entire cornea
• Pain is severe and out of proportion, and is the dominant symptom

Treatment and Applied Aspects

• Treat the systemic disease — this is the priority, and topical measures alone will fail. systemic immunosuppression: high-dose corticosteroid with a steroid-sparing agent — cyclophosphamide in granulomatosis with polyangiitis, methotrexate, mycophenolate, azathioprine, or a biological agent (rituximab, infliximab). Managed jointly with a rheumatologist
• Topical steroids must be used with great caution in a thinning cornea.
• Anticollagenase measures — oral doxycycline (which inhibits matrix metalloproteinases), oral vitamin C, and topical medroxyprogesterone; and topical ciclosporin
• Surgical measures — conjunctival resection adjacent to the ulcer, which removes a source of collagenase and immune cells; tissue adhesive with a bandage lens; amniotic membrane; and lamellar or patch grafting for impending or actual perforation
• Take a systemic history and examine the joints in every peripheral corneal ulcer; the eye may be the presenting organ of a vasculitis
• Send ANCA and urinalysis urgently where there is scleritis with peripheral keratitis; granulomatosis with polyangiitis is treatable and lethal if it is not