Background: Keratitis caused by filamentous fungi is an intractable condition for which judging when to end treatment is difficult. We encountered a patient with keratitis caused by Beauveria bassiana that recurred despite improvement in the condition with eye drop treatment and who ultimately required therapeutic keratoplasty.
Case: The patient was a 66-year-old man with a history of diabetic retinopathy. The man was referred to our department with complaints of eye pain and loss of visual acuity after poking his right eye in a bamboo forest. A circular ulcer and infiltration confined to the surface layer were observed at the center of the cornea, and filamentous fungi were noted on microscopy of corneal scrapings. B. bassiana subsequently developed in the fungal culture. The patient underwent eye drop treatment with pimaricin and voriconazole for 3 months, and the treatment was stopped once his corneal findings improved. However, 1 month later, he developed a deep corneal lesion, and consequently, drug therapy was resumed. Nonetheless, the lesion gradually worsened, and he underwent therapeutic keratoplasty 7 months following his initial examination. Histopathological examination of the removed cornea revealed residual fungi in the endothelium and Descemet's membrane. The patient ultimately underwent penetrating keratoplasty using fresh cornea and has shown no recurrence of fungal infection.
Conclusions: Keratitis caused by B. bassiana progresses extremely slowly and requires careful judgment of when to end treatment. Although patients with keratitis caused by B. bassiana exhibit lesions confined to the shallow layers of the cornea, our findings suggested that the infection can also spread to the deep layers of the cornea.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 122: 523-528, 2018.