Abstract
Purpose :
To determine the time course for maintenance of activity of antimicrobial contact lenses during wear.
Methods :
Twelve experienced contact lens wearers with a mean age of 21.3 ± 3.2 years were randomised to wear contralateral Mel-4-coated and control contact lenses. Contact lenses were aseptically collected from the eyes of wearers after 8 hours, 1 day, 3, 6 and 9 days of wear. Ex-vivo retention of activity was investigated using S. aureus L2260/15 and P. aeruginosa ATCC 27853 immediately after lens collection. Bacterial cells (1.0 x 106 colony forming units per ml) was added to the lenses and incubated at 37°C for 18 hours, after which the numbers of viable bacteria on the lenses were determined by agar plate counts. The retention of activity was analysed using the Wilcoxon Signed Rank Test.
Results :
Contact lenses were worn successfully by ten participants. One participant dropped out of lens wear during the study due to severe dryness and discomfort with both contact lenses. Another participant dropped due to epidemic viral conjunctivitis. The Mel-4-coated contact lenses retained activity against S. aureus for eight hours (2.07 log10 reduction compared to controls), one night (2.15 log10 reduction) and three nights (1.81 log10 reduction) of lens wear (p=0.005) but lost activity at the end of six nights of lens wear (0.22 log10 reduction; p=0.203). For P. aeruginosa, activity was retained for eight hours (1.88 log10 reduction), one night (2.49 log10 reduction) and three nights (0.82 log10 reduction) of lens wear (p=0.005) but it was lost at six nights of lens wear (0.14 log10 reduction; p=0.139).
Conclusions :
Mel-4-coated contact lenses retain antimicrobial activity against S. aureus and P. aeruginosa for at least three nights of wear but lose the activity at six nights of wear. This loss of activity may be due to fouling of the lens surface by tear film components or degradation of the Mel-4 peptide. These possibilities are being examined in follow-up studies.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.