[In vivo confocal microscopy: a new tool for the diagnosis of Acanthamoeba keratitis]

To study the usefulness of in vivo confocal microscopy imaging for the diagnosis of Acanthamoeba keratitis.

A retrospective review of 50 cases of Acanthamoeba keratitis followed at the Quinze-Vingts National Ophthalmology Hospital from January 2005 to July 2008 was conducted. Gender, age, contact lens wear, best-corrected visual acuity before and after treatment, slit-lamp examination findings, corneal scrapings for biological analysis, and in vivo confocal microscopy images were analyzed.

Nearly 82% of the cases of keratitis had a history of contact lens wear. Polymerase chain reaction (PCR) was positive for 40% of the samples. Heidelberg Retinal Tomograph II-Rostock Cornea Module (HRTII-RCM) examination detected images evoking Acanthamoeba cyst-like images in 84% of the cases. When the quality of biological samples was inadequate, the assessment of Acanthamoeba cysts using in vivo confocal microscopy made it possible to orient the diagnosis and to partially explain favorable progression under treatment. This technique showed images suggesting combined Acanthamoeba and fungal keratitis.

HRTII-RCM in vivo confocal microscopy is a non invasive and rapid technique that may be helpful for the diagnosis of Acanthamoeba keratitis, especially when laboratory testing is not contributive and when Acanthamoeba keratitis is combined with a fungal infection.