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Ophthalmic & Physiological Optics ISSN 0275-5408The effect of blue-light blocking spectacle lenses on visual
performance, macular health and the sleep-wake cycle:
a systematic review of the literature
John G Lawrenson1 , Christopher C Hull1 and Laura E Downie2
1
Centre for Applied Vision Research, Division of Optometry and Visual Science, City University of London, London, UK, and 2Department of
Optometry and Vision Sciences, The University of Melbourne, Melbourne, Victoria, Australia
Citation information: Lawrenson JG, Hull CC & Downie LE. The effect of blue-light blocking spectacle lenses on visual performance, macular health
and the sleep-wake cycle: a systematic review of the literature. Ophthalmic Physiol Opt 2017; 37: 644–654. https://doi.org/10.1111/opo.12406
Keywords: blue light blocking, macular Abstract
changes, sleep-wake cycle, spectacles,
systematic review, visual performance Purpose: Blue-blocking (BB) spectacle lenses, which attenuate short-wavelength
light, are being marketed to alleviate eyestrain and discomfort when using digital
Correspondence: John G Lawrenson devices, improve sleep quality and potentially confer protection from retinal pho-
E-mail address: j.g.lawrenson@city.ac.uk totoxicity. The aim of this review was to investigate the relative benefits and
potential harms of these lenses.
Received: 6 June 2017; Accepted: 17 August
Methods: We included randomised controlled trials (RCTs), recruiting adults
2017
from the general population, which investigated the effect of BB spectacle lenses
on visual performance, symptoms of eyestrain or eye fatigue, changes to macular
integrity and subjective sleep quality. We searched MEDLINE, EMBASE, the
Cochrane Library and clinical trial registers, until 30 April 2017. Risk of bias was
assessed using the Cochrane tool.
Results: Three studies (with 136 participants) met our inclusion criteria; these
had limitations in study design and/or implementation. One study compared the
effect of BB lenses with clear lenses on contrast sensitivity (CS) and colour vision
(CV) using a pseudo-RCT crossover design; there was no observed difference
between lens types (log CS; Mean Difference (MD) = 0.01 [ 0.03, 0.01], CV
total error score on 100-hue; MD = 1.30 [ 7.84, 10.44]). Another study mea-
sured critical fusion frequency (CFF), as a proxy for eye fatigue, on wearers of low
and high BB lenses, pre- and post- a two-hour computer task. There was no
observed difference between low BB and standard lens groups, but there was a less
negative change in CFF between the high and low BB groups (MD = 1.81 [0.57,
3.05]). Both studies compared eyestrain symptoms with Likert scales. There was
no evidence of inter-group differences for either low BB (MD = 0.00 [ 0.22,
0.22]) or high BB lenses (MD = 0.05 [ 0.31, 0.21]), nor evidence of a differ-
ence in the proportion of participants showing an improvement in symptoms of
eyestrain or eye fatigue. One study reported a small improvement in sleep quality
in people with self-reported insomnia after wearing high compared to low-BB
lenses (MD = 0.80 [0.17, 1.43]) using a 10-point Likert scale. A study involving
normal participants found no observed difference in sleep quality. We found no
studies investigating effects on macular structure or function.
Conclusions: We find a lack of high quality evidence to support using BB specta-
cle lenses for the general population to improve visual performance or sleep qual-
ity, alleviate eye fatigue or conserve macular health.
644 © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists
Ophthalmic & Physiological Optics 37 (2017) 644–654
, J G Lawrenson et al. Blue-light blocking spectacle lenses
decreased scotopic sensitivity (leading to poorer performance
Introduction
in dim lighting conditions) and disruption of the timing of
Rationale the circadian system.13 Intrinsically photosensitive retinal gan-
Studies, in animal models1,2 and cell culture,3,4 have glion cells, which provide photic input to the central circadian
shown that wavelengths in the blue portion of the electro- clock in the suprachiasmatic nucleus, express melanopsin and
magnetic spectrum (400–500 nm) can induce phototoxic have an absorption peak at approximately 480 nm in the blue
retinal damage. Historically, two mechanisms of photo- part of the spectrum.14
chemical damage have been recognised and eponymously Compared to their intra-ocular counterpart, blue-block-
named as ‘Noell damage’ and ‘Ham damage’ after the ing spectacle lenses have received relatively little scientific
original investigators.1,5 Noell, or Class I, damage was first attention. Standard spectacle lenses generally offer protec-
observed following prolonged exposure of albino rats to tion against UV (up to wavelengths of 380 nm) and the
fluorescent light (490–580 nm). Cellular disruption adding of a yellow chromophore can also reduce or elimi-
occurred initially in photoreceptors, followed by the reti- nate blue light transmission. Alternatively, anti-reflection
nal pigment epithelium (RPE). By contrast, Ham5 (Class interference coatings can be applied to both the anterior
II damage) described disruption that occurred after and posterior lens surfaces, to selectively attenuate parts of
shorter, high intensity light exposures (between 10 s and the blue-violet light spectrum (415 to 455 nm); this range
2 h’ duration). Shorter wavelengths were associated with of wavelengths includes a significant proportion of the blue
more intense cellular damage, initially at the level of the light hazard function15, while the lens remains transparent
RPE, with a peak of the action spectrum occurring at to other wavelengths of visible light. In addition to their
around 440 nm in the phakic eye. International standards putative benefit for retinal protection, blue-blocking spec-
have been developed based on these empirical studies6, tacle lenses have also been claimed to improve sleep quality
which define exposure limits, below which adverse effects following the use of electronic devices at night,16 and
are unlikely to occur. However, driven by requirements reduce eye fatigue and symptoms of eye strain during
for brighter and lower energy lighting, the last 10 years intensive computer tasks.17
has seen significant changes in light sources for both com- A systematic review of the best available research evi-
mercial and domestic applications, with an increased use dence is essential to assess the appropriateness of marketing
of compact fluorescent lamps (CFL) and high intensity blue-blocking spectacle lenses at the general spectacle wear-
light-emitting diodes (LEDs). Moreover, white-light LEDs ing population. This evaluation will consider both the rela-
(the most common type of LED) have become ubiquitous tive benefits and potential harms of these lenses.
in backlit displays in smartphones and tablet computers.
Although the light emitted by these LEDs appears white,
Objectives
their emission spectra show peak emissions at wavelengths
corresponding to the peak of the blue light hazard func- The primary aim of this systematic review is to evaluate the
tion. It has been shown that exposure of cultured RPE effectiveness of blue-blocking spectacle lenses for improv-
cells to light equivalent to that emitted from mobile dis- ing visual performance and reducing visual fatigue. Our
play devices causes increased free radical production and secondary aims are to assess whether these lenses are effec-
reduced cell viability.7 This has raised concerns that the tive in maintaining macular health and to determine any
cumulative exposure to blue light from such sources may positive or negative effects on the sleep-wake cycle. The
induce retinal toxicity and potentially increase the risk of review will attempt to find scientific evidence to answer the
age-related macular degeneration.8 following questions:
The rationale for the introduction of blue-blocking oph-
thalmic lenses was to mitigate the risk of retinal toxicity by 1. Compared to standard (non blue-blocking) spectacle
blocking, or attenuating, short wavelength visible light, usu- lenses, do blue-blocking lenses enhance visual perfor-
ally in the range 400 nm to 500 nm. These ophthalmic mance?
devices, which include spectacle lenses, contact lenses and 2. Compared to standard spectacle lenses, do blue-block-
intra-ocular lenses (IOLs), contain or are coated with dyes ing lenses improve visual comfort and/or reduce symp-
that selectively absorb blue and violet light. The choice toms of visual fatigue?
between a conventional ultraviolet (UV) light blocking IOL 3. What is the evidence that blue-blocking spectacle lenses
and a blue-blocking IOL following cataract surgery has gener- provide protection to the macular and preserve macular
ated significant debate in the literature in terms of achieving a function?
balance between photoreception and photoprotection.9–12 4. What is the evidence that blue-blocking spectacle lenses
Possible disadvantages of blocking short-wavelength visible disrupt circadian entrainment and affect alertness and/
light transmission include disturbances of colour perception, or sleep quality?
© 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists 645
Ophthalmic & Physiological Optics 37 (2017) 644–654
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