Visual and non‐visual properties of filters manipulating short‐wavelength light

Abstract

Purpose Optical filters and tints manipulating short‐wavelength light (sometimes called ‘blue‐blocking’ or ‘blue‐attenuating’ filters) are used in the management of a range of ocular, retinal, neurological and psychiatric disorders. In many cases, the only available quantification of the optical effects of a given optical filter is the spectral transmittance, which specifies the amount of light transmitted as a function of wavelength. Methods We propose a novel physiologically relevant and retinally referenced framework for quantifying the visual and non‐visual effects of these filters, incorporating the attenuation of luminance (luminous transmittance), the attenuation of melanopsin activation (melanopsin transmittance), the colour shift, and the reduction of the colour gamut (gamut reduction). Using these criteria, we examined a novel database of spectral transmittance functions of optical filters (n = 121) which were digitally extracted from a variety of sources. Results We find a large diversity in the alteration of visual and non‐visual properties. The spectral transmittance properties of the examined filters vary widely, in terms of shapes and cut‐off wavelengths. All filters show relatively more melanopsin attenuation than luminance attenuation (lower melanopsin transmittance than luminous transmittance). Across the data set, we find that melanopsin transmittance and luminous transmittance are correlated. Conclusions We suggest that future studies and examinations of the physiological effects of optical filters quantify the visual and non‐visual effects of the filters beyond the spectral transmittance, which will eventually aid in developing a mechanistic understanding of how different filters affect physiology. We strongly discourage comparing the downstream effects of different filters on, e.g. sleep or circadian responses, without considering their effects on the retinal stimulus.

Electrochromic selective filtering of chronodisruptive visible wavelengths

“…With the exception of AUC 1-1.7 (marginally significant differences), all PLR parameters reflected less constriction under the absorptive state with respect to control sample (similar to that previously found for static yellow filters, reviewed in [ 45 ]), while the transmissive state did not produce significant changes in PLR compared to the control. However, when comparing both states (transmissive and absorptive) to each other, we did not find any significant differences in any PLR parameters.…”

“…Also, differences in pupil response driven by chromatic pathways (due to different wavelengths) have been previously described as being 3-fold larger than those driven by luminance pathways (due to different intensities) [ 52 ]. However, photon flux reaching the retina also depends on the pupil area itself, which in turn is modulated by photon flux and the wavelength of the emitting light source [ 45 ]. This may be another factor to take into account when considering the obtained results in pupil size, and then regarding the potential filtering effect on light transmission to the central pacemaker (SCN).…”

Sleep and circadian phenotype in people without cone-mediated vision: a case series of fiveCNGB3and twoCNGA3patients

“…This sensitivity to light is typically managed using optical filters 37 integrated in spectacles or contact lenses. These filters reduce the activation of rods and thereby alleviate visual discomfort and prevent saturation of the rods.…”

Photometric and Colorimetric Evaluation of Phototherapy Instruments for Syntonic Treatment of Visual Anomalies

“…14,30 Even optical filters and tinted lenses, both ophthalmic and intraocular, are sometimes used, and there is no real knowledge of the implications of having filtered light reaching the retina. 31 Photometrically, metamers are stimuli with different spectral power distributions that have the same color and luminance and, consequently, the same visual appearance. This phenomenon is obtained because the visual system integrates across a wide range of wavelengths weighted according to its photoreceptors' spectral sensitivities, having equivalent effective radiance not just for one but for all three cone photoreceptors.…”

“…Only 15 of these studies discussed the application of this therapy technique in visual dysfunctions, all of which had low or very low scientific evidence, and only 8 were experimental studies 14,30 . Even optical filters and tinted lenses, both ophthalmic and intraocular, are sometimes used, and there is no real knowledge of the implications of having filtered light reaching the retina 31 …”