Abstract
PURPOSE: To examine the wavelength characteristics of photochromic contact lenses (CL) and evaluate the impact of tinting on visual function in indoor, outdoor, and glare environments. METHODS: A total of 33 healthy individuals with refractive errors were recruited and fully corrected for refractive errors. Three groups were established, including non-activated photochromic CL, activated photochromic CL, and lenses without photochromic properties, which replicated the dimming characteristics of CL. Visual acuity and contrast sensitivity were measured and compared among the three groups. RESULTS: Statistically significant differences were observed in the spatial frequency (6, 12 cpd) and contrast sensitivity outdoors, with improved values recorded in the activated photochromic-CL group. In subsequent comparisons, the activated-photochromic-CL group demonstrated significantly better contrast-sensitivity values than the non-photochromic-CL group, as well as significant improvement in contrast sensitivity compared to the non-activated-photochromic-CL group. No significant differences were observed in the indoor or outdoor visual acuity. CONCLUSION: Our results suggest that photochromic CL enhances visual function in outdoor environments, while maintaining visual function indoors and under glare, thereby improving the quality of vision (QOV) in severe light conditions where exposure to sunlight and ultraviolet light is anticipated.