Comparison of Culture-negative versus Culture-positive Fungal Keratitis: Clinical Features and Treatment Outcomes

To compare the clinical features and treatment outcomes between culture-negative (CN) and culture-positive (CP) fungal keratitis.

Clinical and microbiology data of patients diagnosed with fungal keratitis at a Tertiary Eye Care Centre in eastern India between January 2021 and December 2022 were retrospectively reviewed. Collected data included demographic details (age, gender, profession), ocular and systemic predisposing factors, history of ocular trauma, clinical presentation, smear and culture reports, management modalities, and treatment outcomes.

Among 283 smear-positive fungal keratitis cases, 152 were CN and 131 were CP. Age, gender, history of ocular trauma, and duration of symptoms were comparable between CP and CN cases (P = 0.1082, 0.4411, 0.3307, and 0.7920, respectively). Absence of prior antimicrobial therapy was more common in the CP group (P = 0.0004). CP cases presented with a poorer visual acuity (P < 0.0001) and larger infiltrate area (P < 0.0001). CN cases showed better outcomes with medical management (P = 0.0028) and shorter treatment duration (P = 0.0435). In contrast, CP cases required more surgical interventions (P = 0.0081), particularly "major" surgical interventions such as therapeutic penetrating keratoplasty, vitreoretinal surgery, and evisceration (P = 0.0125). CP cases had higher rates of treatment failure (P = 0.0442) and worse visual acuity outcomes (P = 0.2831).

CP fungal keratitis is associated with worse presenting visual acuity, larger infiltrate, and poorer treatment outcomes compared with CN fungal keratitis. Culture positivity in fungal keratitis can, therefore, serve as a prognostic indicator for disease severity and may necessitate more aggressive medical management or earlier surgical intervention.