Blue light filters and their effect on the pupil light reflex
The increasing exposure to artificial blue light sources has spawned an equal interest in spectacle lenses that protect against this potentially harmful proportion of light. This study compared the performance of different blue light filtering spectacle lenses and investigated whether a reduction in blue light transmission affects light-dependent physiological processes.
Material and Methods:
The wavelength-specific transmission of various spectacle lenses was determined by spectrometer and the influence of the lenses on the PIPR (Post Illumination Pupil Response) was evaluated. Thirty-six eyes of 18 adults (20 - 30 years) were measured by monocular, direct chromatic pupillometry with and without blue light filtering lenses. The modified pupillometer (PupilX from Albomed GmbH) with red and blue stimulation was used with a pupil exposure time of 30 seconds (darkness: 1 s; light stimulus: 1 s; darkness: 28 s).
In the main action spectrum of the blue light hazard (400 nm ≤ λ ≤ 500 nm), the transparent blue light filter showed 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 curvature index in an exponential interpolation (p < 0.001) when the “comfort- and wellness-” lenses were used.
Blue light filtering lenses have been shown to reduce the transmission of blue light and thus can minimize the risk of blue light exposure. By simultaneously reducing the stimulation of intrinsic photosensitive retinal ganglion cells (ipRGCs), light-modulated physiological processes such as circadian regulation could be altered. The use of “comfort- and wellness” lenses showed a significant change in the PIPR. An influence by transparent, blue-light filtering spectacle lenses could not be detected.
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