Disinfecting solutions for soft contact lenses using different color indicators.
OBJECTIVE
The color change reached in two commercial disinfecting solutions for soft contact lenses using new color indicators has been analyzed, and its relationship with the temporal evolution of the hydrogen peroxide concentration, responsible for the disinfection process, has been examined. The results are compared with another commercial solution using a different color indicator.


METHODS
Color measurements of the disinfecting solutions were performed at 2-minute intervals for over 2 hours using a Photo-Research PR-704 spectroradiometer with horizontal optical axis. Samples were placed at the floor of a VeriVide CAC 120 light booth with a Munsell gray mask behind them. Two different standard light sources, representative of outdoor and indoor illumination, were used. The hydrogen peroxide concentration during the disinfection process was measured for each commercial solution using a Beckman DU-7 spectrophotometer.


RESULTS
The temporal evolutions of color for the two new disinfecting solutions were qualitatively different. CIELAB color differences induced in these two new disinfecting solutions were 1.5 and 2.2 times greater than that measured in the earlier comparative solution and occur in a more appropriate direction of color space for users with defective color vision. Although the earlier solution generated color changes close to the deutan confusion line, the changes produced by the new solutions are close to the tritan confusion line. After 2 hours, the hydrogen peroxide concentration for the two new solutions was approximately one-third the one reached by the earlier solution. There are statistically significant correlations (p < 0.01) between color change and hydrogen peroxide concentration for the two new solutions (r = -0.878 and r = -0.990).


CONCLUSIONS
Color changes in these hydrogen peroxide systems can be used as a safe and useful tool by contact lens wearers. The two new disinfecting solutions analyzed in this article show noteworthy improvements over the earlier solution.
Departamento de Optica, Facultad de Ciencia, Universidad de Granada, Granada, Spain.
Rosa M
RM
García-Monlleó
Maria J
MJ
Rivas
Rafael
R
Huertas
Manuel
M
Melgosa
D003116:Color; D018639:Contact Lens Solutions / Q000737:chemistry*; D003263:Contact Lenses, Hydrophilic; D004203:Disinfection / Q000379:methods / Q000592:standards; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry*; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D013053:Spectrophotometry
D018639:Contact Lens Solutions; D007202:Indicators and Reagents; D006861:Hydrogen Peroxide