Blue-Light Filtering Spectacle Lenses: Optical and Clinical Performances Amber lenses to block blue light and improve sleep: a randomized trial. Effect of Blue Light–Reducing Eye Glasses on Critical Flicker Frequency Short-Wavelength Light-Blocking Eyeglasses Attenuate Symptoms of Eye Fatigue. Wavelength-dependent effects of evening light exposure on sleep architecture and sleep EEG power density in men. Intraocular lenses for the treatment of age-related cataracts: an evidence-based analysis. Effect of blue-blocking glasses in major depressive disorder with sleep onset insomnia: A randomized, double-blind, placebo-controlled study Effect of variable tinted spectacle lenses on visual performance in control subjects.
Purpose s To evaluate the optical performance of blue-light filtering spectacle lenses and investigate whether a reduction in blue light transmission affects visual performance and sleep quality . Methods Experiment 1 : The relative changes in phototoxicity , scotopic sensitivity , and melatonin suppression of five blue-light filtering plano spectacle lenses  were calculated based on their spectral transmittances measured by a spectrophotometer . Experiment 2 : A pseudo-r and omized controlled study was conducted to evaluate the clinical performance of two blue-light filtering spectacle lenses ( BF : blue-filtering anti-reflection coating ; BT : brown-tinted ) with a regular clear lens ( AR ) serving as a control . A total of eighty computer users were recruited from two age cohorts ( young adults : 18–30 yrs , middle-aged adults : 40–55 yrs ) .  Contrast sensitivity under st and ard and glare conditions , and colour discrimination were measured using st and ard clinical tests . After one month of lens wear , subjective ratings of lens performance were collected by question naire . Results All tested blue-light filtering spectacle lenses theoretically reduced the calculated phototoxicity by 10.6 % to 23.6 % . Although use of the blue-light filters also decreased scotopic sensitivity by 2.4 % to 9.6 % , and melatonin suppression by 5.8 % to 15.0 % , over 70 % of the participants could not detect these optical changes . Our clinical tests revealed no significant decrease in contrast sensitivity either with ( 95 % confidence intervals [ CI ] : AR – BT [ –0.05 , 0.05 ] ; AR – BF [ –0.05 , 0.06 ] ; BT – BF [ –0.06 , 0.06 ] ) or without glare ( 95 % CI : AR – BT [ –0.01 , 0.03 ] ; AR – BF [ –0.01 , 0.03 ] ; BT – BF [ –0.02 , 0.02 ] ) and colour discrimination ( 95 % CI : AR – BT [ –9.07 , 1.02 ] ; AR – BF [ –7.06 , 4.46 ] ; BT – BF [ –3.12 , 8.57 ] ) . Conclusion Blue-light filtering spectacle lenses can partially filter high-energy short-wavelength light without substantially degrading visual performance and sleep quality . These lenses may serve as a supplementary option for protecting the retina from potential blue-light hazard . Trial Registration Clinical Trials.gov All light is not equal : blue wavelengths are the most potent portion of the visible electromagnetic spectrum for circadian regulation . Therefore , blocking blue light could create a form of physiologic darkness . Because the timing and quantity of light and darkness both affect sleep , evening use of amber lenses to block blue light might affect sleep quality . Mood is also affected by light and sleep ; therefore , mood might be affected by blue light blockade . In this study , 20 adult volunteers were r and omized to wear either blue-blocking ( amber ) or yellow-tinted ( blocking ultraviolet only ) safety glasses for 3 h prior to sleep . Participants completed sleep diaries during a one-week baseline assessment and two weeks ' use of glasses . Outcome measures were subjective : change in overall sleep quality and positive/negative affect . Results demonstrated that sleep quality at study outset was poorer in the amber lens than the control group . Two- by three-way ANOVA revealed significant ( p < .001 ) interaction between quality of sleep over the three weeks and experimental condition . At the end of the study , the amber lens group experienced significant ( p < .001 ) improvement in sleep quality relative to the control group and positive affect ( p = .005 ) . Mood also improved significantly relative to controls . A replication with more detailed data on the subjects ' circadian baseline and objective outcome measures is warranted Purpose This study aims to evaluate the effect of blocking short-wavelength light on critical flicker frequency ( CFF ) . Design This study is a prospect i ve clinical study . Methods Thirty-three participants ( 17 men and 16 women ; age range , 28–39 years ) were divided into 3 groups . Each group wore 1 of 3 types of lenses while performing an intensive computer task for 2 hours . To evaluate the effect of blocking short-wavelength light before and after the task , we measured the CFF and evaluated subjective question naires . We used the analysis of variance test to examine whether the type of lenses tested affected any of the visual fatigue-related parameters . Results The type of lens worn significantly affected the CFF ; however , answers to the subjective question naires did not differ significantly between the groups . Two of the 13 question items showed a statistical difference between lens transparency and increase in the CFF ( lens 3 > lens 2 > lens 1 ) . Conclusions The higher the blocking effect of the lens , the lower the reduction in the CFF , suggesting that blocking short-wavelength light can reduce eye fatigue Purpose The purpose of this study was to determine whether subjects who wear short wavelength-blocking eyeglasses during computer tasks exhibit less visual fatigue and report fewer symptoms of visual discomfort than subjects wearing eyeglasses with clear lenses . Methods A total of 36 healthy subjects ( 20 male ; 16 female ) was r and omized to wearing no-block , low-blocking , or high-blocking eyeglasses while performing a 2-hour computer task . A masked grade r measured critical flicker fusion frequency ( CFF ) as a metric of eye fatigue and evaluated symptoms of eye strain with a 15-item question naire before and after computer use . Results We found that the change in CFF after the computer task was significantly more positive ( i.e. , less eye fatigue ) in the high-block versus the no-block ( P = 0.027 ) and low-block ( P = 0.008 ) groups . Moreover , r and om assignment to the high-block group but not to the low-block group predicted a more positive change in CFF ( i.e. , less eye fatigue ) following the computer task ( adjusted β = 2.310 ; P = 0.002 ) . Additionally , subjects wearing high-blocking eyeglasses reported significantly less feeling pain around/inside the eye ( P = 0.0063 ) , less feeling that the eyes were heavy ( P = 0.0189 ) , and less feeling that the eyes were itchy ( P = 0.0043 ) following the computer task , when compared to subjects not wearing high-blocking lenses . Conclusions Our results support the hypothesis that short-wavelength light-blocking eyeglasses may reduce eye strain associated with computer use based on a physiologic correlate of eye fatigue and on subjects ' reporting of symptoms typically associated with eye strain Light strongly influences the circadian timing system in humans via non-image-forming photoreceptors in the retinal ganglion cells . Their spectral sensitivity is highest in the short-wavelength range of the visible light spectrum as demonstrated by melatonin suppression , circadian phase shifting , acute physiological responses , and subjective alertness . We tested the impact of short wavelength light ( 460 nm ) on sleep EEG power spectra and sleep architecture . We hypothesized that its acute action on sleep is similar in magnitude to reported effects for polychromatic light at higher intensities and stronger than longer wavelength light ( 550 nm ) . The  sleep EEGs  of eight young men were analyzed after 2-h evening exposure to blue ( 460 nm ) and green ( 550 nm ) light of equal photon densities ( 2.8 x 10(13 ) photons x cm(-2 ) x s(-1 ) ) and to dark ( 0 lux ) under constant posture conditions . The time course of EEG slow-wave activity ( SWA ; 0.75 - 4.5 Hz ) across sleep cycles after blue light at 460 nm was changed such that SWA was slightly reduced in the first and significantly increased during the third sleep cycle in parietal and occipital brain regions . Moreover , blue light significantly shortened rapid eye movement ( REM ) sleep duration during these two sleep cycles . Thus the light effects on the dynamics of SWA and REM sleep duration s were blue shifted relative to the three-cone visual photopic system probably mediated by the circadian , non-image-forming visual system . Our results can be interpreted in terms of an induction of a circadian phase delay and /or repercussions of a stronger alerting effect after blue light , persisting into the sleep episode OBJECTIVE The objective of the report is to examine the comparative effectiveness and cost-effectiveness of various intraocular lenses ( IOLs ) for the treatment of  age-related cataracts .  CLINICAL NEED TARGET POPULATION AND CONDITION A cataract is a hardening and clouding of the normally transparent crystalline lens that may result in a progressive loss of vision depending on its size , location and density . The condition is typically bilateral , seriously compromises visual acuity and contrast sensitivity and increases glare . Cataracts can also affect people at any age , however , they usually occur as a part of the natural aging process . The occurrence of cataracts increases with age from about 12 % at age 50 years , to 60 % at age 70 . In general , approximately 50 % of people 65 year of age or older have cataracts . Mild cataracts can be treated with a change in prescription glasses , while more serious symptoms are treated by surgical removal of the cataract and implantation of an IOL . In Ontario , the estimated prevalence of  cataracts increased from 697,000 in 1992 to 947,000 in 2004 ( 35.9 % increase , 2.4 % annual increase ) . The number of cataract surgeries per 1,000 individuals at risk of cataract increased from 64.6 in 1992 to 140.4 in 1997 ( 61.9 % increase , 10.1 % annual increase ) and continued to steadily increase to 115.7 in 2004 ( 10.7 % increase , 5.2 % increase per year ) . DESCRIPTION OF TECHNOLOGY/THERAPY IOLs are classified either as monofocal , multifocal , or accommodative . Traditionally , monofocal ( i.e .. fixed focusing power ) IOLs are available as replacement lenses but their implantation can cause a loss of the eye 's accommodative capability ( which allows variable focusing ) . Patients thus usually require eyeglasses after surgery for reading and near vision tasks . Multifocal IOLs aim to improve near and distant vision and obviate the need for glasses . Potential disadvantages include reduced contrast sensitivity , halos around lights and glare . Accommodating IOLs are design ed to move with ciliary body contraction during accommodation and , therefore , offer a continuous range of vision ( i.e. near , intermediate and distant vision ) without the need for glasses . Purported advantages over multifocal IOLs include the avoidance of haloes and no reduction in contrast sensitivity .  Polymethyl methacrylate ( PMMA ) was the first material used in the fabrication of IOLs and has inherent ultraviolet blocking abilities . PMMA IOLs are inflexible , however , and require a larger incision for implantation compared with newer foldable silicone ( hydrophobic ) and acrylic ( hydrophobic or hydrophilic ) lenses . IOLs can be further sub-classified as being either aspheric or spheric , blue/violet filtered or non-filtered or 1- or 3-piece . METHODS OF EVIDENCE -BASED ANALYSIS : A literature search was conducted from January 2003 to January 2009 that included OVID MEDLINE , MEDLINE In-Process and Other Non-Indexed Citations , EMBASE , the Cumulative Index to Nursing & Allied Health Literature ( CINAHL ) , The Cochrane Library , and the International Agency for Health Technology Assessment /Centre for Review and Dissemination . Inclusion Criteria Exclusion Criteria adult patients with age-related cataracts systematic review s , r and omized controlled trials ( RCTs ) PRIMARY OUTCOMES distance visual acuity ( best corrected distance visual acuity ) , near visual acuity ( best distance corrected near visual acuity ) SECONDARY OUTCOMES contrast sensitivity , depth of field , glare , quality of life , visual function , spectacle dependence , posterior capsule opacification .  studies with fewer than 20 eyesIOLs for non-age related cataractsIOLs for presbyopia studies with a mean follow-up < 6months studies reporting insufficient data for analysis COMPARISONS OF INTEREST : The primary comparison of interest was accommodative vs. multifocal vs. monofocal lenses . Secondary comparisons of interest included : tinted vs. non-tinted lensesaspheric vs. spheric lensesmultipiece vs. single piece lensesbio material A ( e.g. acrylic ) vs. bio material B ( e.g. silicone ) lensessharp vs. round edged lensesThe quality of the studies was examined according to the GRADE Working Group criteria for grading quality of evidence for interventional procedures . SUMMARY OF FINDINGS The conclusions of the systematic review of IOLs for age-related cataracts are summarized in Executive Summary Table 1 . CONSIDERATIONS FOR THE ONTARIO HEALTH SYSTEM : Procedures for crystalline lens removal and IOL insertion are insured and listed in the Ontario Schedule of Benefits .If a particular lens is determined to be medically necessary for a patient , the cost of the lens is covered by the hospital budget . If the patient chooses a lens that has enhanced features , then the hospital may choose to charge an additional amount above the cost of the usual lens offered . An IOL manufacturer stated that monofocal lenses comprise approximately 95 % of IOL sales in Ontario and premium lenses ( e.g. , multifocal/accomodative ) consist of about 5 % of IOL sales . A medical consultant stated that all types of lenses are currently being used in Ontario ( e.g. , multifocal , monofocal , accommodative , tinted , nontinted , spheric , and aspheric ) . Nonfoldable lenses , rarely used in routine cases , are primarily used for complicated cataract implantation situations . ES Table 1 : Conclusions for the Systematic Review of IOLs for Age-Related CataractsComparison Conclusion GRADE Quality Multifocal vs. monofocal Objective Outcomes Significant improvement in BDCUNVANo significant difference in BCDVAInconclusive evidence for contrast sensitivityInconclusive evidence for glareSubjective Outcomes Inconclusive evidence for visual satisfactionSignificant increase in glare/halosSignificant increase in freedom from spectaclesmoderatemoderatelowvery lowlowlow/moderatelow/moderateAccommodative vs. multifocal/monofocalInconclusive due to Insufficient limited evidence for any effectiveness outcome very lowHydrophilic acrylic vs. other material s ( hydrophobic acrylic , silicone)Significant increase in PCO scoreLowSharp edged compared to round edgedSignificant reduction in PCO scoreLowOne piece compared to three pieceNo significant difference in PCO scorelowHydrophobic acrylic compared to siliconeNo significant difference in PCO scoremoderateAspherical modified prolate anterior surface compared to sphericalNo significant difference in VASignificant reduction in contrast sensitivityvery lowvery lowBlue light filtering compared to non blue-light filteringNo significant difference in BCDVANo significant difference in contrast sensitivityNo significant difference in HRQLlowlowhigh/moderateBCDVA refers to best corrected distance visual acuity ; BDCUNVA , best distance corrected unaided near visual acuity ; HRQL , health related quality of life ; PCO , posterior capsule opacification ; VA , visual acuity ABSTRACT Blue wavelengths form the portion of the visible electromagnetic spectrum that most potently regulates circadian rhythm . We hypothesized that wearing blue-blocking ( BB ) glasses in the evening may influence circadian rhythm disturbances in patients with major depressive disorder ( MDD ) , result ing in improved sleep and mood . We used a r and omized placebo-controlled double-blinded design . Patients with MDD with sleep onset insomnia were r and omly assigned to wearing either BB glasses or clear glasses ( placebo ) . Patients were instructed to wear the glasses from 20:00 hours until bedtime for 2 weeks . We assessed sleep state ( sleep quality on a visual analog scale , the Morningness – Eveningness Question naire [ MEQ ] , and a sleep diary ) and depressive symptoms at baseline and after 2 weeks . Data were analyzed with a full analysis set . In total , 20 patients were r and omly assigned to the BB and placebo groups ( BB group , n = 10 ; placebo group , n = 10 ) . There were three dropouts ( BB group , n = 1 ; placebo group , n = 2 ) . At baseline , sleep quality , sleep latency ( assessed via a sleep diary ) , and antipsychotics use differed between the groups . To take account of these differences , the baseline sleep state or depressive symptoms and antipsychotics use were used as covariates in the later analysis . The change scores for sleep quality did not show a significant improvement in the BB group compared with the placebo group ( mean [ st and ard deviation , SD ] scores for BB versus placebo : 36.1 [ 31.7 ] versus 16.2 [ 15.1 ] , p = 0.43 ) , although half of the BB group showed a clear improvement in sleep quality . The change in MEQ scores did not significantly differ between the groups ( p = 0.14 ) , although there was a trend of a shift to morning type in the BB group ( 3.10 [ 4.95 ] points ) and to evening type in the placebo group ( 0.50 [ 3.89 ] points ) . There were no statistically significant changes in depressive symptoms in either group . Across both groups , 40 % of the participants reported pain or discomfort from wearing the glasses , which were available in only one size . Thus , the failure to find significant differences may have result ed from the glasses used in this study . Glasses fitted to individual patients may improve efficacy and safety . Replication of the study with a larger sample size and size-adjustable glasses is needed PURPOSE To evaluate quantitatively the effects of tinted spectacle lenses on visual performance in individuals without visual pathology . METHODS Twenty-five subjects were assessed by measuring contrast sensitivity with and without glare . Gray , brown , yellow , green , purple , and blue lens tints were evaluated . Measurements were repeated with each lens tint and with a clear lens , and the order was counterbalanced within and between subjects . Glare was induced with a modified brightness acuity tester . RESULTS All subjects demonstrated an increase in contrast thresholds under glare conditions for all lens tints . However , purple and blue lens tints result ed in the least amount of contrast threshold increase ; the yellow lens tint result ed in the largest contrast threshold increase . CONCLUSIONS Purple and blue lens tints may improve contrast sensitivity in control subjects under glare conditions
A study involving normal participants found no observed difference in sleep quality .
We found no studies investigating effects on macular structure or function .
We find a lack of high quality evidence to support using BB spectacle lenses for the general population to improve visual performance or sleep quality , alleviate eye fatigue or conserve macular health
PURPOSE Blue-blocking ( BB ) spectacle lenses , which attenuate short-wavelength light , are being marketed to alleviate eyestrain and discomfort when using digital devices , improve sleep quality and potentially confer protection from retinal phototoxicity .
The aim of this review was to investigate the relative benefits and potential harms of these lenses .