Improvement or worsening of human contrast sensitivity due to blue light attenuation at 450 nm

Abstract

Purpose: The work was aimed at comparing contrast sensitivity performance in an indoor environment with two filters, which differ only in the presence of a band at 450±20 nm in the transmittance spectrum. Patients and Methods: Thirty-nine subjects participated. The filters were the Standard (ST) and Professional (PRO) Drive lenses (Hoya, Japan), the latter showing the attenuation band at 450 nm. Photopic contrast sensitivity (CS) was measured at different spatial frequencies from 1.5 to 18 cpd through Functional Acuity Contrast Test with both lenses (LogCS ST and LogCS PRO, respectively). The areas under the curves of LogCS ST and LogCS PRO as a function of the spatial frequency were also considered. Results: In the range of the measured values of LogCS ST for the thirty-nine participants, at each spatial frequency and also for the areas, the difference Δ = LogCS PRO - LogCS ST was found to decrease and change sign from positive to negative as a function of LogCS ST, thus allowing to deduce a threshold (LogCS threshold) for LogCS ST corresponding to Δ=0. Significant CS worsening was found with the PRO compared to the ST lens for the subjects showing LogCS ST > LogCS threshold. Vice versa, CS improvement was found when LogCS ST < LogCS threshold. Conclusion: In the choice of a blue-filtering lens, practitioners should take into consideration that the attenuation of light in the range 420-470 nm is expected to produce a CS worsening in subjects showing a relatively high initial CS (higher than a threshold CS). For these subjects, the general reduction of transmitted light intensity prevails on possible advantages. On the contrary, subjects showing a relatively low initial CS are expected to show a CS improvement because the attenuation of light in the range 420-470 nm is expected to reduce intraocular scattering and to mimic the effect as an optical filter of the human macular pigment, advantages which prevail on the reduction of the transmitted light intensity.

Publication DOI: https://doi.org/10.2147/OPTO.S242818
Divisions: College of Health & Life Sciences
Additional Information: This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License. By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms.
Uncontrolled Keywords: Blue filtering,Intraocular scattering,Macular pigment,Optics and spectroscopy,Optometry practice,Ophthalmology,Sensory Systems
Publication ISSN: 1444-0938
Full Text Link:
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
https://www.dov ... ed-article-OPTO (Publisher URL)
PURE Output Type: Article
Published Date: 2020-04-01
Accepted Date: 2020-03-20
Authors: Tavazzi, Silvia
Cozza, Federica
Nigrotti, Gabriele
Braga, Chiara
Vlasak, Natalia
Larcher, Silvano
Zeri, Fabrizio (ORCID Profile 0000-0003-0529-555X)

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