Abstract
Purpose :
Photodynamic antimicrobial chemotherapy (PACT) is a promising alternative to antibiotics for combating infectious diseases. Our previous studies have demonstrated the efficacy of PACT, specifically utilizing the photosensitizer TONS504, against various microorganisms. While most research in ophthalmology has focused on treating established infectious keratitis, our study aims to assess the applicability of PACT to contact lens hygiene, potentially reducing the incidence of infectious keratitis.
Methods :
Soft contact lenses (FDA classification group 4) were incubated in culture media containing Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. After a 12-hour incubation, lenses were exposed to 0.1, 1.0, or 10 mg/L TONS504 solution or PBS without TONS504, followed by light exposure at 665 nm wavelength, activating the photosensitizer. Total irradiated light energy was 30 J/cm2. Post-irradiation, lenses were transferred to PBS, microorganisms were detached, and the resulting PBS solution underwent serial dilution and agar transfer. Colony counts were log10-transformed and statistically analyzed (Tukey-Kramer test, p<0.05).
Results :
PACT with 0.1 mg/L TONS504 significantly reduced S. aureus by approximately 2 log10, while 1.0 and 10 mg/L concentrations achieved a reduction of over 6 log10. However, PACT did not significantly reduce P. aeruginosa and C. albicans at any concentration.
Conclusions :
TONS504-PACT exhibited significant antimicrobial efficacy against S. aureus on soft contact lenses but lacked effectiveness against P. aeruginosa and C. albicans. Refinement of treatment procedures, potentially incorporating additives to enhance PACT effects, is necessary for applying PACT to contact lens hygiene.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.