2007 OMIG, Abstract 15

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Acanthamoeba Keratitis: Risk factors, Clinical Characteristics and Outcomes
Iyer SA, Tuli SS, Driebe WT
University of Florida, Gainesville

Purpose: To review the risk factors, clinical characteristics and treatment outcome in patients with acanthamoeba keratitis (AK).
Methods: Retrospective review of medical records of consecutive patients with AK presenting to the University of Florida Eye Center from January 1999 to June 2006. Diagnosis of AK was based on positive corneal culture or confocal microscopy.
Results: Twenty-eight patients with AK were identified. Average age at presentation was 36 years. 86% of patients were women. 23 patients (82%) wore soft contact lenses (CL) and 2 patients (7%) wore rigid gas-permeable CL. 24% of patients used tap/well water in CL care. 68% swam/showered and 16% used a hot tub while wearing CLs. Presenting clinical features included severe pain 64%, anterior stromal infiltrates/opacities 61%, epitheliopathy (including pseudodendrites, raised epithelial lines, epithelial microerosions) 50%, radial keratoneuritis 46%, corneal edema 43%, ring infiltrate 36%, epithelial defect in 28%, deep stromal infiltrate 14% and hypopyon 7%. More than one clinical feature was present in all patients at the time of diagnosis. 57% patients were diagnosed by positive confocal microscopy and 43% by positive corneal cultures. 81% of patients that needed confocal microscopy for diagnosis had ring &/or deep stromal infiltrates at presentation. In contrast, all culture positive patients presented with predominant epitheliopathy &/or anterior stromal infiltrates. 46% of patients were previously treated for herpes simplex keratitis. Average time to diagnosis of AK after onset of symptoms was shorter in the culture positive group (24 days vs. 88 days in the confocal group). All patients were treated with a combination of topical propamidine isethionate 0.1% (Brolene), polyhexamethylene biguanide (PHMB 0.02%) and clotrimazole 1% for an average duration of 217 days. All cases resolved with medical therapy alone and no patients needed emergent surgical intervention. 3 patients underwent elective penetrating keratoplasty for corneal scarring at a mean interval of 16 months after presentation. At average follow-up of 19 months, 76% of patients had best-corrected visual acuity of 20/40 or better.
Conclusions: Diagnosis of AK is often delayed because of failure to recognize the diverse clinical signs. Poor contact lens hygiene continues to remain an important risk factor. Confocal microscopy is helpful in establishing the diagnosis of AK in the presence of ring infiltrates. Prolonged and aggressive topical medical therapy with a combination of antiamoebic agents results in medial cure and good final visual acuity.

Disclosure code: N

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