Effect of Contact Lenses on Contrast Sensitivity under Various Lighting Conditions

Abstract

Purpose: To assess contrast sensitivity in clear and colored soft contact lenses under different lighting conditions.

Methods: This study was performed on 34 medical students. Visual acuity was measured using a tumbling E chart at a distance of 6 m, and contrast sensitivity was determined by Pelli Robson chart at a distance of 1 m. These tests were repeated in mesopic (3 lux) and glare (2000 lux) conditions. Then, a clear contact lens was applied to one eye and a colored contact lens was applied to the other. After 2 hr, visual acuity and contrast sensitivity were measured for each individual. The results were compared with and without contact lenses under normal, mesopic, and glare conditions.

Results: The mean refractive error was 0.44 $\pm$ 0.20 diopters. Repeated measures ANOVA showed a decline in contrast sensitivity with colored and clear contact lenses as compared to no-lens condition (P $<$ 0.001). Additionally, lighting conditions had a significant impact on contrast sensitivity (P $<$ 0.001); contrast sensitivity was lower in mesopic and glare conditions than under normal lighting condition.

Conclusion: In addition to the drop in contrast sensitivity under unusual lighting conditions (e.g., glare and mesopic), wearing soft contact lenses can further reduce contrast sensitivity in different lighting conditions. Therefore, people who wear contact lenses should be aware of this reduction in visual performance in conditions like driving at night or in the fog.

Keywords: Contrast Sensitivity; Glare; Visual Acuity; Contact Lens.