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. Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays. Blue light filtering intraocular lenses in phacoemulsification cataract surgery. Both coloured overlays and coloured lenses can improve reading fluency, but their optimal chromaticities differ. Clinical results of the blue‐light filtering AcrySof Natural foldable acrylic intraocular lens Effects of an advanced sleep schedule and morning short wavelength light exposure on circadian phase in young adults with late sleep schedules. Intraindividual comparison of color contrast sensitivity in patients with clear and blue‐light‐filtering intraocular lenses Effects of wearing yellow spectacles on visual skills, reading speed, and visual symptoms in children with reading difficulties Non-Visual Effects of Light on Melatonin, Alertness and Cognitive Performance: Can Blue-Enriched Light Keep Us Alert? High sensitivity of the human circadian melatonin rhythm to resetting by short wavelength light. Human phase response curve to intermittent blue light using a commercially available device. Randomized trial of multifocal intraocular lenses versus monovision after bilateral cataract surgery. Will Visual Discomfort among Visual Display Unit (VDU) Users Change in Development When Moving from Single Vision Lenses to Specially Designed VDU Progressive Lenses? Effect of magnification lenses on student operator posture. Benefit of coloured lenses for age-related macular degeneration. Acute exposure to evening blue-enriched light impacts on human sleep.
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 We selected 68 children who reported benefit from individually chosen sheets of coloured plastic placed upon the page when reading , and who used these regularly without prompting . These children viewed text illuminated by coloured light in an apparatus that allowed the separate manipulation of hue ( colour ) and saturation ( depth of colour ) , at constant luminance . Many of the children reported improvements in perception when the light had a chromaticity within a limited range , which was different for each individual . A pair of plastic spectacle lenses ( ' experimental ' lenses ) was dyed so as to provide the appropriate chromaticity under conventional white ( F3 ) fluorescent light . An additional pair was prepared having very similar colour but with a chromaticity outside the range in which perception was reported to improve ( ' control ' lenses ) . Each pair was provided for 1 month in r and om order . The children kept diaries ( 36 completed ) recording symptoms of eye-strain and headache . The children and those responsible for their assessment were unable reliably to distinguish ' experimental ' from ' control ' lenses . Nevertheless , symptoms were less frequent on days when the ' experimental ' lenses were worn ( P < 0.003 ) Blue light can damage retina and cause age related macular degeneration . After cataract surgery and lens removal retina stays unprotected . Blue light filtering intraocular lenses ( IOL ) increase protection of the retina . In our prospect i ve study we investigated clinical results after bilateral implantation of Acrysof Natural IOL to 30 patients ( N = 60 eyes ) . In a control group ( N = 60 eyes , 30 patients ) ,  st and ard acrysof IOL was implanted bilaterally . Uncorrected visual acuity ( UCVA ) , best corrected visual acuity ( BCVA ) and Nd YAG laser capsulotomy rate were measured and compared with control group . Subjective patient 's satisfaction and subjective colour perception were also investigated . There was no significant difference in UCVA , BCVA and Nd YAG laser capsulotomy rate between the two groups . High patient 's satisfaction was noticed ( 96.7 % of patients would implant Acrysof Natural IOL again ) . Acrysof Natural IOL enables good visual acuity VA , low rate of Nd YAG laser capsulotomy and high patient 's satisfaction without colour perception disturbances Some individuals read more fluently when the text is coloured : i.e. , when coloured sheets of plastic ( overlays ) are placed upon the page , or when coloured lenses are worn . Overlays provide a surface colour whereas lenses mimic a change in the colour of a light source . The neural mechanisms that underlie colour constancy ensure that the chromaticity of overlays and lenses is processed differently by the visual system . We investigated ( 1 ) the relationship between the optimal colours of overlays and lenses , and ( 2 ) how reading rate is affected by a particular colour in overlays and lenses .  In 100 patients we noted ( 1 ) the overlay(s ) chosen from among the 29 combinations of the 10 IOO Intuitive Overlays which sample chromaticity systematic ally and ( 2 ) the chromaticity co-ordinates of the lenses subsequently chosen using the intuitive Colorimeter , a device providing a light source that can be adjusted in hue , saturation and luminance independently . The relationship between the chromaticities of the overlays and the lenses showed considerable variation . In a second study , patients attending the Specific Learning Difficulties clinic at the Institute of Optometry , London , were given overlays to use for two months . Seventeen who derived benefit were examined using the  Intuitive Colorimeter .  Patients were asked to read aloud r and omly ordered common words ( Wilkins Rate of Reading Test ) : ( 1 ) with no colour , ( 2 ) with the chosen overlay , ( 3 ) with lenses matching the chosen overlay and ( 4 ) with lenses matching the Colorimeter setting . The aids increased reading rate significantly only in conditions ( 2 ) and ( 4 ) . There was no significant improvement when lenses matching the overlay colour were used , and under this condition the reading rate was significantly poorer than in conditions ( 2 ) and ( 4 ) . The colour of a lens will improve reading only if it is selected under conditions that mimic a change in the colour of a light source : coloured overlays give no clinical ly reliable guide to optimal lens colour PURPOSE : To verify the safety and effectiveness of the new AcrySof Natural ( Alcon Laboratories , Inc. ) blue‐light filtering intraocular lens ( IOL ) , which was design ed to achieve a light‐transmission spectrum similar to that of the natural human crystalline lens . SETTING : Multicenter U.S. clinical trial . METHODS : In a prospect i ve r and omized patient‐masked multicenter study , 150 patients received the AcrySof Natural IOL and 147 patients received the AcrySof single‐piece IOL as a control . Patients with bilateral age‐related cataracts who were willing and able to wait at least 30 days between cataract procedures and had verified normal preoperative color vision were eligible for the study . St and ardized surgery included a 4.0 to 5.0 mm capsulorhexis and phacoemulsification . All lenses were inserted in the capsular bag , with verification of in‐the‐bag placement of both haptics . In all bilateral implantation cases , the same model IOL was used in each eye . Postoperatively , contrast sensitivity and color perception were measured up to 180 days and up to 1 year ( for visual acuity ) after implantation . RESULTS : No statistically significant differences were discovered between the 2 patient groups in visual acuity , contrast sensitivity evaluated under mesopic and photopic conditions , or the number of patients who passed the Farnsworth D‐15 color perception test . There were no lens‐related adverse events in either group . CONCLUSIONS : The blue‐light filtering AcrySof Natural IOL was equivalent to the conventional AcrySof lens in terms of postoperative visual performance . Additional long‐term clinical studies should show whether the IOL actually provides the theoretical benefits to retinal health OBJECTIVE We examined the effects of an advanced sleep/wake schedule and morning short wavelength ( blue ) light in 25 adults ( mean age±SD=21.8±3 years ; 13 women ) with late sleep schedules and sub clinical features of delayed sleep phase disorder ( DSPD ) . METHODS After a baseline week , participants kept individualized , fixed , advanced 7.5-h sleep schedules for 6days . Participants were r and omly assigned to groups to receive " blue " ( 470 nm , ∼225lux , n=12 ) or " dim " ( < 1lux , n=13 ) light for 1h after waking each day . Head-worn " Daysimeters " measured light exposure ; actigraphs and sleep diaries confirmed schedule compliance . Salivary dim light melatonin onset ( DLMO ) , self-reported sleep , and mood were examined with 2 × 2 ANOVA . RESULTS After 6days , both groups showed significant circadian phase advances , but morning blue light was not associated with larger phase shifts than dim-light exposure . The average DLMO advances ( mean±SD ) were 1.5±1.1h in the dim light group and 1.4±0.7h in the blue light group . CONCLUSIONS Adherence to a fixed advanced sleep/wake schedule result ed in significant circadian phase shifts in young adults with sub clinical DSPD with or without morning blue light exposure . Light/dark exposures associated with fixed early sleep schedules are sufficient to advance circadian phase in young adults PURPOSE : To evaluate the effect of blue‐light‐filtering intraocular lenses ( IOLs )  with a yellow chromophore on color contrast sensitivity by intraindividual comparison with an identically design ed IOL without a blue‐light filter . SETTING : Medical University of Vienna , Department of Ophthalmology , Vienna , Austria . METHODS : R and omized implantation of an AF‐1 ( UV ) IOL ( Hoya ) in 1 eye and an AF‐1 ( UY ) IOL ( Hoya ) in the contralateral eye was performed after phacoemulsification and primary posterior curvilinear capsulorhexis . Three months postoperatively , the best distance‐corrected visual acuity was evaluated . Before color contrast sensitivity testing , a heterochromatic flicker test was performed in both eyes to avoid error in brightness matching . Central and peripheral tritan color contrast sensitivities were evaluated using the Moorfields Vision System ( CH Electronics ) . RESULTS : Visual acuity did not differ significantly between the 2 IOL groups ( P>.05 ) . The central color contrast sensitivity threshold also did not differ significantly between eyes with a clear IOL and eyes with a yellow IOL at any tested spatial frequency . The peripheral color contrast sensitivity test showed slightly higher color contrast sensitivity thresholds in eyes with a yellow IOL , although the differences were not statistically significant . Two patients independently reported subjective changes in color perception in the eye with the yellow IOL . CONCLUSION : In this intraindividual comparison , the implantation of a blue‐light‐filtering IOL did not lead to a clinical ly significant change in color contrast sensitivity Background Possible beneficial effects of yellow-tinted spectacle lenses on binocular vision , accommodation , oculomotor scanning , reading speed and visual symptoms were assessed in children with reading difficulties . Methods A longitudinal prospect i ve study was performed in 82 non-dyslexic children with reading difficulties in grade s 3–6 ( aged 9–11 years ) from 11 elementary schools in Madrid ( Spain ) . The children were r and omly assigned to two groups : a treatment ( n = 46 ) and a without-treatment group ( n = 36 ) . Children in the treatment group wore yellow spectacle lenses with best correction if necessary over 3 months ( in school and at home ) . The tests were first undertaken without the yellow filter . With best spectacle correction in each subject , measurements were made of : distance and near horizontal heterophoria , distance and near horizontal fusional vergence ranges , the accommodative convergence/accommodation ( AC/A ) ratio , near point of convergence ( NPC ) , stereoacuity , negative relative accommodation ( NRA ) and positive relative accommodation ( PRA ) , monocular accommodative amplitude ( MAA ) , binocular accommodative facility ( BAF ) , oculomotor scanning , and reading speed ( words per minute ) . The Convergence Insufficiency Symptom Survey ( CISS ) question naire was completed by all children . After the 3-month period , measurements were repeated with the yellow lenses ( treatment group ) or without the yellow lenses ( without-treatment group ) but with refractive correction if needed . Results Over the 3 months , the two groups showed similar mean changes in the variables used to assess binocular vision , accommodation , oculomotor scanning , and reading speed . However , mean relative changes in convergence insufficiency symptoms differed significantly between the groups ( p = 0.01 ) . Conclusion No effects of wearing yellow spectacles emerged on binocular vision , accommodation , oculomotor scanning , and reading speed in children with reading difficulties . The yellow filter had no effect even in children with low MAA and BAF . The reduction in visual symptoms observed in children with reading difficulties using the yellow filters was clinical ly insignificant Background Light exposure can cascade numerous effects on the human circadian process via the non-imaging forming system , whose spectral relevance is highest in the short-wavelength range . Here we investigated if commercially available compact fluorescent lamps with different colour temperatures can impact on alertness and cognitive performance . Methods Sixteen healthy young men were studied in a balanced cross-over design with light exposure of 3 different light setting s ( compact fluorescent lamps with light of 40 lux at 6500 K and at 2500 K and inc and escent lamps of 40 lux at 3000 K ) during 2 h in the evening . Results Exposure to light at 6500 K induced greater melatonin suppression , together with enhanced subjective alertness , well-being and visual comfort . With respect to cognitive performance , light at 6500 K led to significantly faster reaction times in tasks associated with sustained attention ( Psychomotor Vigilance and GO/NOGO Task ) , but not in tasks associated with executive function ( Paced Visual Serial Addition Task ) . This cognitive improvement was strongly related with attenuated salivary melatonin levels , particularly for the light condition at 6500 K . Conclusions Our findings suggest that the sensitivity of the human alerting and cognitive response to polychromatic light at levels as low as 40 lux , is blue-shifted relative to the three-cone visual photopic system . Thus , the selection of commercially available compact fluorescent lights with different colour temperatures significantly impacts on circadian physiology and cognitive performance at home and in the workplace The endogenous circadian oscillator in mammals , situated in the suprachiasmatic nuclei , receives environmental photic input from specialized subsets of photoreceptive retinal ganglion cells . The human circadian pacemaker is exquisitely sensitive to ocular light exposure , even in some people who are otherwise totally blind . The magnitude of the re setting response to white light depends on the timing , intensity , duration , number and pattern of exposures . We report here that the circadian re setting response in humans , as measured by the pineal melatonin rhythm , is also wavelength dependent . Exposure to 6.5 h of monochromatic light at 460 nm induces a two-fold greater circadian phase delay than 6.5 h of 555 nm monochromatic light of equal photon density . Similarly , 460 nm monochromatic light causes twice the amount of melatonin suppression compared to 555 nm monochromatic light , and is dependent on the duration of exposure in addition to wavelength . These studies demonstrate that the peak of sensitivity of the human circadian pacemaker to light is blue-shifted relative to the three-cone visual photopic system , the sensitivity of which peaks at approximately 555 nm . Thus photopic lux , the st and ard unit of illuminance , is inappropriate when quantifying the photic drive required to reset the human circadian pacemaker Light shifts the timing of the circadian clock according to a phase response curve ( PRC ) . To date , all human light PRCs have been to long duration s of bright white light . However , melanopsin , the primary photopigment for the circadian system , is most sensitive to short wavelength blue light . Therefore , to optimise light treatment it is important to generate a blue light PRC.We used a small , commercially available blue LED light box , screen size 11.2 × 6.6 cm at ∼50 cm , ∼200 μW cm(−2 ) , ∼185 lux . Subjects participated in two 5 day laboratory sessions 1 week apart . Each session consisted of circadian phase assessment s to obtain melatonin profiles before and after 3 days of free-running through an ultradian light – dark cycle ( 2.5 h wake in dim light , 1.5 h sleep in the dark ) , forced desynchrony protocol . During one session subjects received intermittent blue light ( three 30 min pulses over 2 h ) once a day for the 3 days of free-running , and in the other session ( control ) they remained in dim room light , counterbalanced . The time of blue light was varied among subjects to cover the entire 24 h day . For each individual , the phase shift to blue light was corrected for the free-run determined during the control session . The blue light PRC had a broad advance region starting in the morning and extending through the afternoon . The delay region started a few hours before bedtime and extended through the night . This is the first PRC to be constructed to blue light and to a stimulus that could be used in the real world OBJECTIVE To compare spectacle independence in patients r and omized to receive bilateral multifocal intraocular lenses ( IOLs ) or monofocal IOLs  with the powers adjusted to produce monovision . DESIGN R and omized , multicenter clinical trial . PARTICIPANTS A total of 212 patients with bilateral , visually significant cataract . METHODS Before bilateral sequential cataract surgery , patients were r and omized ( allocation ratio 1:1 ) to receive bilateral Tecnis ZM900 diffractive multifocal lenses ( Abbott Medical Optics , Santa Ana , CA ) or Akreos AO monofocal lenses ( Bausch & Lomb , Rochester , NY ) with the powers adjusted to target -1.25 diopters ( D ) monovision . Outcomes were assessed 4 months after the second eye underwent operation . MAIN OUTCOME MEASURES The primary outcome was spectacle independence . Secondary outcomes included question naires ( VF-11R , dysphotopsia symptoms , and satisfaction ) and visual function measures ( near , intermediate , and distance logarithm of minimum angle of resolution [ logMAR ] visual acuity , stereoacuity , contrast sensitivity , and forward light scatter ) . RESULTS A total of 212 patients were r and omized , and 187 patients ( 88 % ) returned for assessment 4 months after surgery . Uniocular distance refractions in the monovision arm showed a mean spherical equivalent of + 0.075 D in the distance eye and -0.923 in the near eye . In the multifocal arm , the mean distance spherical equivalents were -0.279 D and -0.174 D in the right and left eyes , respectively . A total of 24 of 93 patients ( 25.8 % ) in the monovision arm and 67 of 94 patients ( 71.3 % ) in the multifocal arm reported never wearing glasses ( P<0.001 , Fisher exact test ) . The adjusted odds ratio of being spectacle free was 7.51 ( 95 % confidence interval , 3.89 - 14.47 ) . Binocular uncorrected acuities did not differ significantly for distance ( 0.058 logMAR for monovision vs. 0.076 for multifocal , P = 0.3774 ) but were significantly worse in the multifocal arm for intermediate acuity ( 0.149 vs. 0.221 , P = 0.0001 ) and in the monovision arm for near acuity ( 0.013 vs. -0.025 , P = 0.037 ) . In the first postoperative year , 6 patients ( 5.7 % ) in the multifocal arm underwent IOL exchange ( 4 had a bilateral and 2 had a unilateral exchange ) . No patients in the monovision arm underwent IOL exchange . CONCLUSIONS Patients r and omized to  bilateral implantation with the diffractive multifocal Tecnis ZM900 were more likely to report being spectacle independent but also more likely to undergo IOL exchange than those r and omized to receive monofocal implants ( Akreos AO ) with the powers adjusted to give low monovision Purpose . Three types of progressive additions lenses ( PAL ) specially design ed for VDU-work and one single vision lens were compared in a prospect i ve field study . The aim was to investigate if these progressive lenses created a difference in the development of visual discomfort compared to single vision lenses when working on an optimized VDU-workstation . Methods . The study had a prospect i ve , parallel group design , with four groups of VDU-workers . Approximately 40 subjects in each group , selected after careful task analysis with special attention towards the visual angles and distances to the work tasks . The groups were followed over one year . A question naire concerning visual conditions , working conditions , discomfort in different body areas , the status of the subjects ’ optometric corrections , psychological factors both at work and at home , amount , frequency and duration of VDU-work etc . was filled in before the intervention , after six months and after one year . No other contact was made with the subjects . The VDU-lenses included were Interview ( Essilor ) , Gradal RD ( Zeiss ) and Technica ( American Optical ) . Pain intensity and duration were assessed on a 100 mm Visual Analogue Scale ( VAS ) before the intervention , and six and twelve months after the intervention . All subjects were given a complete optometric examination . Results . Only small changes in the development of headache and visual discomfort were registered . However , the subjective evaluation of area of clear vision and overall satisfaction was significantly improved for the Interview and Gradal RD lens ( p < 0.05 ) . There were no significant changes for Technica and single vision lenses . Conclusion . Lens design s that cover viewing distances from near and out to approximately 2 meters work well compared to lens design s trying to cover greater range of clear vision . When tasks analysis shows that single vision correction may be used , this is still an acceptable solution A distinct body of literature supports the association between clinical postures of the dental practitioner and work-related musculoskeletal disorders ( WRMD ) . Several aids or devices have been tested to improve clinical posture in the interest of decreasing WRMD . The use of magnification lenses while performing dental procedures may increase the quality of work and decrease the likelihood of musculoskeletal problems . To date , only anecdotal and personal opinions had existed regarding the benefits of using magnification lenses , and no empirical evidence had authenticated the contention that use of magnification lenses exerts a positive change in operator posture . The objective of this study was to assess the effect magnification lenses had on the posture of dental hygiene students . Using a r and omized crossover design , research ers videotaped nineteen senior dental hygiene students performing an intra-oral procedure with and without the use of magnification lenses . The tapes were then evaluated by a panel of five dental hygiene educators calibrated in the use of Branson 's Posture Assessment Instrument ( PAI ) . Results of a paired t-test indicate that the posture of the students while wearing magnification lenses was more acceptable ( p=.019 ) than when wearing traditional safety glasses . Results of this study indicate a quantifiable change in acceptability of posture for clinicians wearing magnification lenses  and suggest that the use of such lenses in dental education may be warranted PURPOSE To evaluate and compare the functional and perceived benefits of wearing coloured lenses by patients with age-related macular degeneration ( ARMD ) . METHOD Ten subjects with early ARMD and five elderly controls wore a selection of NoIR wrap-around coloured lenses ( yellow 29.7 % light transmission , orange 22.9 % , red 16.8 % and grey 10.3 % ) , each for a duration of 7 days . Contrast sensitivity , colour vision , visual acuity , the effect of glare and peripheral sensitivity were measured for each lens and compared with a control ( no lens ) condition . Subjective ratings of visual performance were also scored . RESULTS Compared with the no filter condition , red and grey lenses reduced contrast sensitivity whereas yellow and orange lenses increased contrast sensitivity . These objective changes were supported by subjective ratings in subjects with ARMD . Grey lenses reduced the loss of contrast sensitivity usually suffered in the presence of glare , whereas visual acuity and peripheral sensitivity decreased with red lenses . Colour vision became distorted with red lenses in control subjects , but was relatively unaffected by the use of coloured lenses in subjects with ARMD . CONCLUSIONS The subjective benefit of coloured lenses appears to be due to a minor enhancement of contrast sensitivity Light in the short wavelength range ( blue light : 446 - 483 nm ) elicits direct effects on human melatonin secretion , alertness and cognitive performance via non-image-forming photoreceptors . However , the impact of blue-enriched polychromatic light on human sleep architecture and sleep electroencephalographic activity remains fairly unknown . In this study we investigated sleep structure and sleep electroencephalographic characteristics of 30 healthy young participants ( 16 men , 14 women ; age range 20 - 31 years ) following 2 h of evening light exposure to polychromatic light at 6500 K , 2500 K and 3000 K.  Sleep structure across the first three non-rapid eye movement non-rapid eye movement - rapid eye movement sleep cycles did not differ significantly with respect to the light conditions . All-night non-rapid eye movement sleep electroencephalographic power density indicated that exposure to light at 6500 K result ed in a tendency for less frontal non-rapid eye movement electroencephalographic power density , compared to light at 2500 K and 3000 K. The dynamics of non-rapid eye movement electroencephalographic slow wave activity ( 2.0 - 4.0 Hz ) , a functional index of homeostatic sleep pressure , were such that slow wave activity was reduced significantly during the first sleep cycle after light at 6500 K compared to light at 2500 K and 3000 K , particularly in the frontal derivation . Our data suggest that exposure to blue-enriched polychromatic light at relatively low room light levels impacts upon homeostatic sleep regulation , as indexed by reduction in frontal slow wave activity during the first non-rapid eye movement episode
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 .