Blue Light Filtering Spectacle Lenses: Intensity of Attenuation and its Effect on the Pupil Light Reflex

Abstract

Purpose : The increasing exposure to artificial blue light sources such as LEDs has spawned intense interest in spectacle lenses that protect against this potentially dangerous proportion of light. This study sought to compare the performance of different blue light filtering spectacle lenses. We investigated whether a reduction in blue light transmission affects light-dependent physiological processes.

Methods : We used a spectrometer to determine the wavelength-specific transmission of various spectacle lenses. In addition, the relative changes in phototoxicity and melatonin suppression were visualized based on their spectral transmittances. A total of 36 eyes from 18 adults (20 – 30 years) were measured by monocular, direct chromatic pupillometry with and without blue light filtering lenses. The pupillometer (PupilX by Albomed® GmbH) was used (l_red » 662 nm; E_e,lred » 0,0536 Wm^-2nm^-1 / l_blue » 465 nm; E_e,lblue » 0,0489 Wm^-2nm^-1) with a pupil exposure time of 30 seconds (dark exposure: 1 s; light stimulus: 1 s; dark exposure: 28 s).

Results : All spectacle lenses, with the exception of two, absorbed the near UV rays (maximum transmission: 0.93 %). In the main action spectrum of the blue light hazard (400 nm ≤ l ≤ 500 nm), the transparent blue light filtering spectacle lenses showed a lower absorption compared to “comfort- and wellness” lenses of filter category 1 (absorption: 19.60 % to 25.27 % and 65.04 % to 97.43 %).
In the early and late phase of the post illumination pupil reflex (PIPR) after a blue light stimulus, we detected a significantly smaller area under the curve (p < 0.001), a larger normalized pupil diameter (p < 0.001), and a larger amount of curvature (p < 0.001) when the “comfort- and wellness-” lenses were used. There were no significant differences between the results without lenses or transparent blue light filtering lenses.

Conclusions : Blue light filtering lenses can minimize the risk of blue light exposure. The lack of participation of intrinsic photosensitive retinal ganglion cells (ipRGCs) in the PIPR after blue light stimuli using “comfort- and wellness” lenses indicates an inhibition, which could interfere with light-dependent physiological processes, e.g. sleep quality. An influence due to the transparent blue light filtering spectacle lenses could not be verified.

This is a 2020 ARVO Annual Meeting abstract.