DECREASED CORNEAL SENSATION AS AN INITIAL FEATURE OF ACANTHAMOEBA-KERATITIS

Background: Herpes simplex keratitis is the most common misdiagnosis i n patients with Acanthamoeba keratitis, which is increasing in frequen cy and is associated with daily wear soft contact lenses. Both entitie s usually present as unilateral keratitis. The manifestations of super ficial Acanthamoeba keratitis (i.e., unilaterality, dendriform appeara nce, positive response to antivirals, and decreased corneal sensation) increase the opportunity for misdiagnosis as herpes simplex keratitis . The authors have encountered six patients with Acanthamoeba keratiti s in whom the correct diagnosis was delayed from 2 weeks to 3 months. Methods: All six patients underwent testing with the Cochet-Bonnet est hesiometer and extensive pharmacologic treatment for herpes simplex ke ratitis. Corneal scrapings were taken between 2 and 6 weeks after the initial examination. Results: In all six patients, corneal sensation w as decreased significantly. Drug therapy was ineffective. Cultures wer e positive for Acanthamoeba. Five of six patients underwent penetratin g keratoplasty. Conclusions: Decreased corneal sensation has contribut ed to the misdiagnosis of Acanthamoeba as herpes simplex keratitis. Mi sdiagnosis results in delayed treatment and worse outcome. The authors found that significantly decreased corneal sensation is a frequent fi nding in early Acanthamoeba keratitis. Therefore, physicians should co nsider Acanthamoeba keratitis as an alternative diagnosis in patients with presumed herpes simplex keratitis with decreased corneal sensatio n.