Ricardo Lamy1, Elliot Chan1, Samuel D Good1, Vicky Cevallos2, Travis C Porco2, Jay M Stewart1. 1. Department of Ophthalmology, University of California - San Francisco, San Francisco, California, USA. 2. Francis I. Proctor Foundation, University of California - San Francisco, San Francisco, California, USA.
Abstract
BACKGROUND: Experimental studies have shown that the standard dose of riboflavin (R) or R + ultraviolet-A (UVA) as solo treatment are not able to exterminate Acanthamoeba cysts or even trophozoites. The purpose of this study is to determine whether the application of R + UVA can enhance the cysticidal effects of cationic antiseptic agents in vitro. METHODS: The log of either polyhexamethylene biguanide or chlorhexidine minimal cysticidal concentration in solutions containing riboflavin (concentrations 0.1, 0.05 and 0.025%) plus either Acanthamoeba castellanii cysts or Acanthamoeba polyphaga cysts was determined and compared in groups treated with UVA 30 mW/cm(2) for 30 min and in control groups (with no exposure to UVA). A permutation test was used to determine the P value associated with treatment. RESULTS: Regardless of the riboflavin concentration and UVA treatment condition, no trophozoites were seen in plates where the cysts were previously exposed to cationic antiseptic agent concentrations ≥200 µg/mL for Acanthamoeba castellanii samples and ≥100 µg/mL for A. polyphaga samples. There was no statistical evidence that R + UVA treatment was associated with minimal cysticidal concentration (P = 0.82). CONCLUSION: R + UVA in doses up to 10 times higher than recommended for corneal crosslinking does not enhance the cysticidal effect of either polyhexamethylene biguanide or chlorhexidine in vitro.
BACKGROUND: Experimental studies have shown that the standard dose of riboflavin (R) or R + ultraviolet-A (UVA) as solo treatment are not able to exterminate Acanthamoeba cysts or even trophozoites. The purpose of this study is to determine whether the application of R + UVA can enhance the cysticidal effects of cationic antiseptic agents in vitro. METHODS: The log of either polyhexamethylene biguanide or chlorhexidine minimal cysticidal concentration in solutions containing riboflavin (concentrations 0.1, 0.05 and 0.025%) plus either Acanthamoeba castellanii cysts or Acanthamoeba polyphaga cysts was determined and compared in groups treated with UVA 30 mW/cm(2) for 30 min and in control groups (with no exposure to UVA). A permutation test was used to determine the P value associated with treatment. RESULTS: Regardless of the riboflavin concentration and UVA treatment condition, no trophozoites were seen in plates where the cysts were previously exposed to cationic antiseptic agent concentrations ≥200 µg/mL for Acanthamoeba castellanii samples and ≥100 µg/mL for A. polyphaga samples. There was no statistical evidence that R + UVA treatment was associated with minimal cysticidal concentration (P = 0.82). CONCLUSION: R + UVA in doses up to 10 times higher than recommended for corneal crosslinking does not enhance the cysticidal effect of either polyhexamethylene biguanide or chlorhexidine in vitro.
Authors: María A del Buey; José A Cristóbal; Paula Casas; Pilar Goñi; Antonio Clavel; Enrique Mínguez; Elena Lanchares; Alicia García; Begoña Calvo Journal: Am J Ophthalmol Date: 2011-10-11 Impact factor: 5.258