[Bilateral acanthamoeba keratitis].

BACKGROUND

Given the protracted clinical course, diagnostic difficulties, frequent treatment failures and the increasing incidence, keratitis caused by free-living acanthamoeba represents a clinical challenge.

PATIENT AND METHODS

A 37-year-old healthy female who wore gas-permeable contact lenses for ten years developed bilateral keratouveitis, pseudodentritic subepithelial infiltrates and corneal ring ulcers. Cultures were obtained from corneal scrapings, contact lenses and storage container. Medical treatment during the clinical course included propamidine isethionate, miconazole, ketoconazole, polymyxin B, aminoglycoside antibiotics and corticosteroids. Surgical procedures included bilateral penetrating keratoplasty and extracapsular cataract extraction. Each corneal button was examined after chemofluorescent staining with calcofluor white.

RESULTS

Klebsiella oxytoca and Serratia marcescens were grown from cultures of the contact lens storage container. Although suspected early in the clinical course repeated cultures from corneal scrapings were negative for acanthamoeba. Despite transient remission, medical therapy including therapy for acanthamoeba could not halt the progression of infection in both eyes. Visual acuity deteriorated to light perception and counting fingers, respectively. Penetrating keratoplasty was performed 12 and 15 months after the onset of symptoms. Histopathological examination allowed identification of acanthamoeba cysts in each button. Because of secondary cataract formation cataract-extraction with intraocular lens implantation was simultaneously performed in the right and subsequently in the left eye. While corneal infiltrates recurred and optic atrophy developed due to secondary glaucoma in the right eye, the left corneal graft has remained clear.

CONCLUSIONS

The case-report demonstrates that diagnostic procedures may fail to detect acanthamoeba organisms before obtaining a corneal button for histopathologic examination. Decreased corneal sensation later in the clinical course after initial pain disproportionately related to clinical signs does not exclude the diagnosis of an acanthamoeba keratitis. Medical treatment failure may occur despite early initiation of antiparasitic therapy.