Blue Filter Contact Lenses May Aid Tear Stability, Contrast Sensitivity

Contact lenses with blue filters may help improve tear stability and enhance contrast sensitivity, according to a study published in Eye & Contact Lens. Researchers compared the tear production and contrast sensitivity of contact lenses containing the filters with unfiltered silicone hydrogel lenses. 

Researchers evaluated the lenses in 20 participants (mean age 22.27±2.05 years). Clinicians examined each participant at 3 visits. On the first visit, they asked participants to spend time outdoors and not to use any digital devices for 3 hours before the evaluation. On the second visit, they asked participants to use some type of digital device continuously during the 3 hours before the study. On the final visit, they asked participants to again use a digital device continuously for 3 hours prior, but this time to wear contact lenses — 1 with a blue light–blocking filter in the left eye, and 1 without the filter in the right.

The participants were evaluated using The Standard Patient Evaluation of Ocular Dryness questionnaire, tear breakup time (TBUT) monocular visual acuities, and contrast sensitivities.

The investigators found differences in contrast sensitivity between the lens types. TBUT decreased in all participants after using video-display terminals (VDT) (P <.05), but researchers reported no differences in TBUT for the blue-light filter pilot group vs the control group (P >.05). However, the research team did note higher mean values in the blue-filter group following VDT utilization vs those wearing unfiltered contact lenses (P >.05). The average value of phenol red testing following the use of VDT decreased after the use of the blue filter (P >.05). 

“The higher the blocking effect of the lens, the lower the reduction in the flicker frequency. [This suggests] that blocking short-wavelength light can reduce eye fatigue,” according to the researchers. “Contact lenses used with a blue light filter were found to improve contrast sensitivity by counteracting a part of the dazzling blue-violet radiation and providing favorable conditions for encoding visual signals from photoreceptors.”

The study’s limitations include its small sample size and the presence of confounding variables, such as humidity and ventilation that could potentially affect eye irritation and tear stability. Investigators also used different electronic devices for different participants, which could have emitted different frequencies of blue light.

Reference

Sánchez-González MC, Madroñero M, García-Romera MC, et al. Effect of blue light filters on tear and contrast sensitivity in individuals using electronic devices. Eye Contact Lens. 2021;47(12):642-646. doi:10.1097/icl.0000000000000843