Abstract
PurposeOptical 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.MethodsWe 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.ResultsWe 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.ConclusionsWe 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.
Highlights
Optical filters can be used to modify the visual input by blocking or attenuating light at specific parts of the visible spectrum[1,2]
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
Data were interpolated to 1 nm resolution using piecewise cubic hermite interpolating polynomial (PCHIP) interpolation
Summary
Optical filters can be used to modify the visual input by blocking or attenuating light at specific parts of the visible spectrum[1,2]. -called blue-blocking or blue-attenuating filters reduce the amount of short-wavelength light at the eye’s surface, the cornea. This is typically realised using one of two ways: 1) using a cut-off filter, which blocks or attenuates light below a specific wavelength, 2) using a notch filter, which blocks or attenuates light within a specific short-wavelength light. Optical filters alter the spectral distribution of the light incident on the retinal surface relative to no filtering[3]. This has direct effects on the activation of the cones and rods in the retina, which allow us to see during the day and night, respectively. The activity of the melanopsin-containing retinal ganglion cells, is modulated by the use of optical filters
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