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2025 OMIG Abstract

Clinical Outcomes and in vitro Susceptibility Analysis of Fungal Keratitis Treated with Adjunct Rose Bengal Photodynamic Antimicrobial Therapy (RB-PDAT) at the Federal University of Sao Paulo (UNIFESP)

Aileen Miwa Tabuse, Camila Kase, Talita T Rocchetti, Maria Cecilia Z Yu, Mauro SQ Campos,
Denise de Freitas, Ana L Hofling-Lima

Federal University of São Paulo – UNIFESP, São Paulo, Brazi

Purpose: To evaluate the clinical efficacy and in vitro antifungal activity RB-PDAT in patients with fungal keratitis treated between December 2019 and January 2025.

Methods: A retrospective analysis was conducted including patient demographics, risk factors, and ophthalmic findings. Clinical evaluation included best corrected visual acuity, slit-lamp examination, and anterior segment photography. Microbiological diagnosis was confirmed by corneal scraping, and antifungal susceptibility testing was performed for amphotericin B (AMB) and voriconazole (VCN). Patients were eligible for RB-PDAT if they showed no clinical improvement with standard antifungal therapy. The primary outcome was ulcer resolution without the need for therapeutic penetrating keratoplasty (TPK); the secondary outcome was time to clinical resolution. In vitro susceptibility to RB-PDAT was assessed for all isolated organisms.

Results: Fourteen patients (14 eyes) were enrolled. The average interval between symptom onset and treatment initiation was 33 days. The most common pathogen was Fusarium solani (4 cases), followed by Purpureocillium lilacinum (2 cases). Other isolates included F. proliferatum, F. delphinoides, F. fujikuroi, Curvularia spp., Colletotrichum spp., Pichia ohmeri, Candida albicans, and Exophiala oligosperma. Five isolates demonstrated resistance to the antifungal used. Clinical success was achieved in 13 (69,2%) cases, with an average resolution time of 47.5 ± 27.5 days. Four patients required TPK after a mean of 29.5 ± 23.5 days due to corneal perforation or persistent infection. All TPK cases presented with hypopyon and deep stromal infiltrates and received adjunctive treatments including intravenous and subconjunctival VCN and intracameral or intrastromal AMB. In vitro, RB-PDAT demonstrated >90% growth inhibition for all organisms except Curvularia spp., a dematiaceous filamentous fungus.

Conclusions: RB-PDAT is an adjunct therapy with consistent results of in vitro inhibition and may be used for clinical treatment of fungi keratitis.