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S. A. Iyer, S. S. Tuli, W. T. Driebe, Jr., A. Neelakantan; Acanthamoeba Keratitis: Risk Factors, Clinical Characteristics and Treatment Outcomes. Invest. Ophthalmol. Vis. Sci. 2007;48(13):761.
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To review the risk factors, clinical characteristics and treatment outcome in patients with acanthamoeba keratitis (AK)
Retrospective review of medical records of consecutive patients with AK presenting to the University of Florida Eye Clinic from January 1999 to December 2004. Diagnosis of AK was based on positive corneal culture or positive confocal microscopy.
Seventeen consecutive patients with AK were identified. Average age at presentation was 37 years. 88% of patients were women. 14 patients (82%) wore soft contact lenses (SCL). 4 patients (29%) used tap/well water in SCL care. 8 patients (57%) gave a history of swimming with SCL and 3 patients (21%) used a hot tub while wearing SCL. Presenting clinical features included epitheliopathy (including pseudodendrites, subepithelial opacification, epithelial defects, epithelial erosions and epithelial granularity) in 77%, severe pain in 65%, corneal edema in 59%, radial keratoneuritis in 47%, ring infiltrate in 35%, anterior stromal infiltrates in 24%, and hypopyon in 6%. More than one clinical feature was present in all patients at the time of diagnosis. 59% patients were diagnosed by positive confocal microscopy and 41% by positive culture from corneal scrapings. All patients with ring infiltrates were culture negative and needed confocal microscopy for diagnosis. In contrast, all culture positive patients had predominant epitheliopathy. Most patients (94%) were tertiary referrals to our eye center. 47% of patients were previously treated as herpes simplex keratitis. Average time to diagnosis of AK after onset of symptoms was 45 days. In all patients triple antiamoebic therapy was started with propamidine 0.1% (Brolene), polyhexamethylene biguanide (PHMB 0.02%) and clotrimazole 1%. 5 patients had to discontinue Brolene due to toxicity. One patient was switched to chlorhexidine 0.02% and paromycin 1.5% because of intolerance to triple therapy. Average duration of completed treatment was 235 days. All cases of AK resolved with medical therapy alone and no emergent surgical intervention was required. One patient underwent elective penetrating keratoplasty for corneal scarring at a later date. Follow-up of six months or more was available in thirteen patients at which time BCVA was 20/30 or better in 69% of patients.
Diagnosis of AK is often delayed because of failure to recognize the diverse clinical signs. Aggressive topical medical therapy with a combination of antiamoebic agents over a prolonged period of time results in medial cure. Good visual outcome is achieved in most patients.
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