To describe femtosecond laser-assisted corneal biopsy and its use in assessing the causative organism in a case of fungal keratitis that occurred 8 months after penetrating keratoplasty.

A 27-year-old man who had undergone penetrating keratoplasty 8 months prior showed atypical diffuse corneal haze and erosion. Diagnostic corneal biopsy using a femtosecond laser was performed because of repeated negative test results for an infectious organism and a lack of improvement, despite steroid and empirical antibiotic therapy. A corneal flap 200 µm in depth and 3 mm in diameter was obtained. The biopsy showed pseudohyphae, which led to a diagnosis of Candidal keratitis. No complications occurred during the procedure.

Femtosecond laser-assisted corneal biopsy enabled identification of the infectious pathogen. This technique is easy, safe, and rapid, and it yields a biopsy specimen with a uniform depth and precise size. Femtosecond laser-assisted corneal biopsy can be used as an accurate diagnostic method in uncertain cases of corneal ulcers.