Abstract
Purpose :
To develop an ex vivo porcine fungal keratitis (FK) model of Aspergillus fumigatus infection and to investigate the treatment efficacy of Photoactivated chromophore for infectious keratitis cross-linking (PACK-CXL) alone or combined with natamycin eyedrop therapy.
Methods :
FK was induced in fresh harvested porcine corneas via corneal abrasion, application of 1-100 spores of YFP A. fumigatus and culture in PBST-PS or RPMI-PS for up to 48 hours. Fungal growth into the stroma was monitored using high-resolution confocal microscopy at 24, 36- and 48-hour time-points to determine optimal conditions.
Using these optimized conditions, 23 corneas were infected and randomly divided into four groups: A: control group without treatment, B: natamycin treatment (0.039mg/L, 20 μL topical administration, every 2 hours for 6 hour period), C: “epi-off” PACK-CXL (VEGA CBM X-Linker), 30 minutes UV-A radiation (5.4J/cm2, with topical riboflavin every 5 minutes); and D: dual therapy (PACK-CXL immediately followed by 2-hourly natamycin). Fungal burden was measured using confocal microscopy up to 1mm depth. Treatment efficacy was determined by comparing the change in fungal burden before and after treatment.
Results :
A reproducible FK penetrating >400μm into the stroma occurred with; PBST-PS, use of 1-10 spores/cornea, and 36-48 hours incubation. Dual therapy (natamycin and PACK-CXL) decreased the fungal burden by 69%. Natamycin decreased fungal burden by 14%, whereas PACK-CXL increased fungal burden by 1%. The control group increased fungal burden by 167%.
Conclusions :
In this study, we developed a standardized ex vivo porcine model of FK. Employing this model, we demonstrated that natamycin combined with PACK-CXL was the most effective treatment in reducing fungal burden compared to each treatment alone, providing evidence for this therapeutic regimen for early to moderate FK. This ex vivo model allows more accurate testing of novel antifungal therapies through direct visualization and quantification of fungal burden within corneal tissue.
This is a 2020 ARVO Annual Meeting abstract.