Abstract

Purpose: Photochromic contact lenses darken when exposed to sunlight protecting intraocular structures from UV damage. This study investigated the impact of PCL on visual functions in both indoor and outdoor conditions. Methods: Subjects aged 18-35 years of existing contact lens users with refractive errors of ≤-5.00DS and ≤-1.00DC. In the randomly chosen eye, baseline measurements were obtained with CCL followed by PCL measurements. High and low contrast visual acuities, vernier acuity, and contrast sensitivity were measured using FrACT software in indoor illumination of 250-300 lux and outdoor illumination of 5000-10000 lux. Color discrimination was assessed digitally using FM 100 hue test and photo stress recovery time was also measured. The jigsaw puzzle game was done and evaluated subjective comfort by using a survey questionnaire. Results: The median difference of HCVA and LCVA between indoor and outdoor conditions with CCL was 0.01 [p=0.26] and -0.15 [p=0.02]. However, with PCL, the median difference of HCVA and LCVA between indoor and outdoor conditions was -0.295 [p=0.86] and -0.2 [p=0.01]. The median difference of contrast sensitivity of different spatial frequencies with CCL and PCL between indoor and outdoor conditions were -0.72, -0.64 [12 cpd], -0.94, -0.87 [15 cpd], and -0.62, 1.3 [18 cpd]. Among the different spatial frequencies, the 18 cpd in CCL [p= 0.02] and 12 cpd [p=0.05] in PCL between indoor and outdoor conditions were statistically significant. The median difference in color vision between indoor and outdoor conditions with CCL and PCL was -13 [p=0.27] and -3.5 [p=0.50]. The PSRT was improved by 2s with PCL than CCL [p 0.08]. The glare discomfort and glare disability were better in PCL [0.9 ± 0.96, 1.4 ± 0.50] than in CCL [-0.05 ±0.68, 1.95 ± 0.88] in outdoor conditions. Conclusion: Photochromic contact lenses enhanced visual functions in both indoor and outdoor conditions, alleviated glare discomfort, and improved glare disability, proving its effectiveness in various environments.