Fusarium keratitis in an older adult without exogenous or traumatic risk factors: A case report on intrinsic ocular surface predisposition.

Objective: To report a case of Fusarium keratitis in an 80-year-old female without typical exogenous or traumatic risk factors, such as ocular trauma, contact lens use, or previous ocular surgery, but with intrinsic ocular surface predisposing factors, and to highlight the diagnostic value of MALDI-TOF MS. Methods: Routine bacterial and fungal cultures were performed on ocular secretion samples from the patient. Lactophenol cotton blue staining was used for microscopic examination, and MALDI-TOF MS (Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry) was employed for rapid and accurate identification of the fungal strain. Clinical data were comprehensively analyzed. Results: White, cotton-like fungal colonies were observed on blood agar and chocolate agar plates. Microscopic examination revealed transparent, septate hyphae and numerous long, oval conidia, initially suggesting Fusarium spp. MALDI-TOF MS analysis showed a high-confidence match with Conclusion: This study highlights the clinical value of MALDI-TOF MS in the identification of pathogens in complex ocular infections. Despite the absence of typical exogenous or traumatic risk factors, the patient developed rapidly progressive invasive keratitis. This case suggests that intrinsic ocular surface abnormalities in older adults, including tear film instability, epithelial barrier impairment, and corneal nerve degeneration, may lower the threshold for fungal infection. The possible contribution of immunosenescence should be interpreted only as contextual background and remains to be validated in future studies.