Multicenter prospective observational study of fungal keratitis in Japan: analyses of culture-positive cases

Purpose To investigate the clinical characteristics and causative fungi in patients with fungal keratitis in Japan, and to determine factors related to the prognosis. Study design Multicenter prospective observational study. Methods Eligible patients were enrolled from November 2011 to October 2013 at the 1st stage and from April 2015 to March 2016 at the 2nd stage. The corneal foci were scraped, and the scrapings were cultured in potato dextrose agar. The isolated fungi were identified by gene analyses. Data were collected from the clinical records and statistically analyzed by Cox and logistic regression analyses. Results Ninety-four fungal strains were isolated from 93 cases, including 42 yeast-like fungi and 52 filamentous fungi. The fungi affected the deep layers of the cornea in 23 cases (24.7%) and the peripheral cornea in 29 cases (31.2%). The incidences of lid swelling/redness, ciliary injection, anterior chamber cells/flare, anterior chamber fibrin, and hyphate ulcer in cases of filamentous fungi were significantly higher than in yeast-like fungi. No history of topical steroids, absence of a main lesion in the peripheral cornea, and best-corrected visual acuity (BCVA) of more than 0.04 at the first visit were related to a shorter healing time. No history of ocular surgery, absence of lesion at one-third deep stromal layer and BCVA of more than 0.04 at the first visit were correlated with BCVA at 3 months after the initial examination. Conclusion Fungal keratitis is caused by various species of fungi and can become refractory due to poor prognosis factors.