Analysis of a Systematic Review About Blue Light-Filtering Intraocular Lenses for Retinal Protection: Understanding the Limitations of the Evidence

Impact of red and blue monochromatic light on the visual system and dopamine pathways in juvenile zebrafish

BACKGROUND

The development of the zebrafish visual system is significantly influenced by exposure to monochromatic light, yet investigations into its effects during juvenile stages are lacking. This study evaluated the impacts of varying intensities and durations of red and blue monochromatic light on the visual system and dopamine pathways in juvenile zebrafish.

METHODS

Juvenile zebrafish were exposed to red (650 nm) and blue (440 nm, 460 nm) monochromatic lights over four days at intensities ranging from 500 to 10,000 lx, for durations of 6, 10, and 14 h daily. A control group was maintained under standard laboratory conditions. Post-exposure assessments included the optokinetic response (OKR), retinal structural analysis, ocular dopamine levels, and the expression of genes related to dopamine pathways (Th, Dat, and Mao).

RESULTS

(1) OKR enhancement was observed with increased 440 nm light intensity, while 460 nm and 650 nm light exposures showed initial improvements followed by declines at higher intensities. (2) Retinal thinning in the outer nuclear layer was observed under the most intense (10,000 lx for 14 h) light conditions in the 440 nm and 650 nm groups, while the 460 nm group remained unaffected. (3) Dopamine levels increased with higher intensities in the 440 nm group, whereas the 460 nm group exhibited initial increases followed by decreases. The 650 nm group displayed similar trends but were statistically insignificant compared to the control group. (4) Th expression increased with light intensity in the 440 nm group. Dat showed a rising and then declining pattern, and Mao expression significantly decreased. The 460 nm group exhibited similar patterns for Th and Dat to the behavioral observations, but an inverse pattern for Mao. The 650 nm group presented significant fluctuations in Th and Dat expressions, with pronounced variations in Mao.

CONCLUSIONS

Specific red and blue monochromatic light conditions promote visual system development in juvenile zebrafish. However, exceeding these optimal conditions may impair visual function, highlighting the critical role of dopamine pathway in modulating light-induced effects on the visual system.

Do blue light filter applications improve sleep outcomes? A study of smartphone users' sleep quality in an observational setting

Exposure to blue light at bedtime, suppresses melatonin secretion, postponing the sleep onset and interrupting the sleep process. Some smartphone manufacturers have introduced night-mode functions, which have been claimed to aid in improving sleep quality. In this study, we evaluate the impact of blue light filter application on decreasing blue light emissions and improving sleep quality. Participants in this study recorded the pattern of using their mobile phones through a questionnaire. In order to evaluate sleep quality, we used a PSQI questionnaire. Blue light filters were used by 9.7% of respondents, 9.7% occasionally, and 80% never. The mean score of PSQI was more than 5 in 54.10% of the participants and less than 5 in 45.90%. ANOVA test was performed to assess the relationship between using blue light filter applications and sleep quality (p-value = 0.925). The findings of this study indicate a connection between the use of blue light filter apps and habitual sleep efficiency in the 31-40 age group. However, our results align only to some extent with prior research, as we did not observe sustained positive effects on all parameters of sleep quality from the long-term use of blue light filtering apps. Several studies have found that blue light exposure can suppress melatonin secretion, exacerbating sleep problems. Some studies have reported that physical blue light filters, such as lenses, can affect melatonin secretion and improve sleep quality. However, the impact of blue light filtering applications remains unclear and debatable.

Blue-Light Filtering Monofocal Intraocular Lenses: A Study on Optical Function and Tolerance to Misalignment

PURPOSE

To investigate the optical performance and tolerance to misalignment of blue-light filtering monofocal intraocular lenses (IOLs).

METHODS

The optical properties of two monofocal IOLs featuring yellow chromophores, CT Lucia 621 PY (Carl Zeiss Meditec AG) and Clareon CNA0T0 (Alcon Laboratories, Inc), were assessed in monochromatic and polychromatic light while introducing spherical aberration (SA). Optical quality metrics derived from the modulation transfer function were assessed after optimal IOL centration at 3- and 4.5-mm pupils. In addition, each IOL's tolerance to misalignment was examined by inducing up to 1 mm of decentration and the effect of tilting it by 5 degrees at 3 mm.

RESULTS

The IOLs' resolution and contrast, while tested using a 3-mm aperture and an SA-neutral corneal model, indicated the CT Lucia 621 PY had a slightly higher modulation transfer function (MTF) at 50 lp/mm than the CNA0T0 under monochromatic conditions (0.77 vs 0.69). On introducing SA with (0.49 vs 0.40) and without (0.75 vs. 0.70) chromatic aberration, the CT Lucia 621 PY maintained its minimally better performance. When assessed with a 4.5-mm aperture in monochromatic light, the CT Lucia 621 PY displayed improved MTF with aberration-free cornea (0.71 vs 0.40) but performed worse after introducing SA (0.44 vs 0.62). However, both lenses achieved comparable MTF values under spherical and chromatic aberrations (0.28 vs 0.27). The IOL misalignment test revealed a better tolerance to tilt and decentration of the CT Lucia 621 PY across all conditions.

CONCLUSIONS

The CT Lucia 621 PY and CNA0T0 showed similar optical quality in different situations, with equal simulated distance visual acuity for both models. However, the CT Lucia 621 PY's aspheric design offers an advantage when dealing with often imperfect physiological conditions, displaying a more robust performance under tilt and decentration. [J Refract Surg. 2024;40(2):e79-e88.].

[Blue light and intraocular lenses (IOLs): Beliefs and realities]

The first intraocular lenses (IOLs) used for cataract surgery transmitted both ultraviolet (UV) radiation and visible light to the retina. Colorless UV-blocking IOLs were introduced and rapidly adopted in the 1980s. Yellow-tinted blue-blocking (also known as blue-filtering) IOLs were marketed in the early 1990s. Blue-blocking IOLs were intended to simulate age-related crystalline lens yellowing to reduce the cyanopsia that some patients experienced after cataract surgery. When blue-filtering IOLs were introduced in North America, however, blue-blocking chromophores were advocated as a way to protect patients from age-related macular degeneration (AMD) despite the lack of evidence that normal environmental light exposure causes AMD. The "blue light hazard" is a term that describes the experimental finding that acute, abnormally intense light exposures are potentially more phototoxic to the retina when short rather than long wavelengths are used. Thus, in brief exposures to intense light sources such as welding arcs, ultraviolet radiation is more hazardous than blue light, which is more hazardous than longer wavelength green or red light. International commissions have cautioned that the blue light hazard does not apply to normal indoor or outdoor light exposures. Nonetheless, the hazard is used for commercial purposes to suggest misleadingly that ambient environmental light can cause acute retinal phototoxicity and increase the risk of AMD. Very large epidemiological studies show that blue-blocking IOLs do not reduce the risk or progression of AMD. Additionally, blue-filtering IOLs or spectacles cannot decrease glare disability, because they decrease image and glare illuminance in the same proportion. Blue light is essential for older adults' scotopic photoreception needed to reduce the risk of nighttime falling and related injuries. It is also critical for circadian photoreception that is essential for good health, sleep and cognitive performance. Unfortunately, age-related pupillary miosis, retinal rod and ganglion cell photoreceptor degeneration and decreased outdoor activity all reduce the amount of healthful blue light available to older adults. Blue-restricting IOLs further reduce the available blue light at a time when older adults need it most. Patients and ophthalmologists are exposed to hypothesis-based advertisements for blue-filtering optical devices that suppress short wavelength light critical for vision in dim lighting and for good physical and mental health. Spectacle and intraocular lens selections should be based on scientific fact, not conjecture. Ideal IOLs should improve photoreception rather than limit it permanently. Practice efficiency, surgical convenience and physician-manufacturer relationships may eliminate a patient's opportunity to choose between colorless blue-transmitting IOLs and yellow-tinted, blue-restricting IOLs. Cataract surgeons ultimately determine whether their patients have the opportunity to make an informed choice about their future photoreception.

Blue-light filtering spectacle lenses for visual performance, sleep, and macular health in adults

BACKGROUND

'Blue-light filtering', or 'blue-light blocking', spectacle lenses filter ultraviolet radiation and varying portions of short-wavelength visible light from reaching the eye. Various blue-light filtering lenses are commercially available. Some claims exist that they can improve visual performance with digital device use, provide retinal protection, and promote sleep quality. We investigated clinical trial evidence for these suggested effects, and considered any potential adverse effects.

OBJECTIVES

To assess the effects of blue-light filtering lenses compared with non-blue-light filtering lenses, for improving visual performance, providing macular protection, and improving sleep quality in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; containing the Cochrane Eyes and Vision Trials Register; 2022, Issue 3); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and WHO ICTRP, with no date or language restrictions. We last searched the electronic databases on 22 March 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), involving adult participants, where blue-light filtering spectacle lenses were compared with non-blue-light filtering spectacle lenses.

DATA COLLECTION AND ANALYSIS

Primary outcomes were the change in visual fatigue score and critical flicker-fusion frequency (CFF), as continuous outcomes, between baseline and one month of follow-up. Secondary outcomes included best-corrected visual acuity (BCVA), contrast sensitivity, discomfort glare, proportion of eyes with a pathological macular finding, colour discrimination, proportion of participants with reduced daytime alertness, serum melatonin levels, subjective sleep quality, and patient satisfaction with their visual performance. We evaluated findings related to ocular and systemic adverse effects. We followed standard Cochrane methods for data extraction and assessed risk of bias using the Cochrane Risk of Bias 1 (RoB 1) tool. We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

We included 17 RCTs, with sample sizes ranging from five to 156 participants, and intervention follow-up periods from less than one day to five weeks. About half of included trials used a parallel-arm design; the rest adopted a cross-over design. A variety of participant characteristics was represented across the studies, ranging from healthy adults to individuals with mental health and sleep disorders. None of the studies had a low risk of bias in all seven Cochrane RoB 1 domains. We judged 65% of studies to have a high risk of bias due to outcome assessors not being masked (detection bias) and 59% to be at high risk of bias of performance bias as participants and personnel were not masked. Thirty-five per cent of studies were pre-registered on a trial registry. We did not perform meta-analyses for any of the outcome measures, due to lack of available quantitative data, heterogenous study populations, and differences in intervention follow-up periods. There may be no difference in subjective visual fatigue scores with blue-light filtering lenses compared to non-blue-light filtering lenses, at less than one week of follow-up (low-certainty evidence). One RCT reported no difference between intervention arms (mean difference (MD) 9.76 units (indicating worse symptoms), 95% confidence interval (CI) -33.95 to 53.47; 120 participants). Further, two studies (46 participants, combined) that measured visual fatigue scores reported no significant difference between intervention arms. There may be little to no difference in CFF with blue-light filtering lenses compared to non-blue-light filtering lenses, measured at less than one day of follow-up (low-certainty evidence). One study reported no significant difference between intervention arms (MD - 1.13 Hz lower (indicating poorer performance), 95% CI - 3.00 to 0.74; 120 participants). Another study reported a less negative change in CFF (indicating less visual fatigue) with high- compared to low-blue-light filtering and no blue-light filtering lenses. Compared to non-blue-light filtering lenses, there is probably little or no effect with blue-light filtering lenses on visual performance (BCVA) (MD 0.00 logMAR units, 95% CI -0.02 to 0.02; 1 study, 156 participants; moderate-certainty evidence), and unknown effects on daytime alertness (2 RCTs, 42 participants; very low-certainty evidence); uncertainty in these effects was due to lack of available data and the small number of studies reporting these outcomes. We do not know if blue-light filtering spectacle lenses are equivalent or superior to non-blue-light filtering spectacle lenses with respect to sleep quality (very low-certainty evidence). Inconsistent findings were evident across six RCTs (148 participants); three studies reported a significant improvement in sleep scores with blue-light filtering lenses compared to non-blue-light filtering lenses, and the other three studies reported no significant difference between intervention arms. We noted differences in the populations across studies and a lack of quantitative data. Device-related adverse effects were not consistently reported (9 RCTs, 333 participants; low-certainty evidence). Nine studies reported on adverse events related to study interventions; three studies described the occurrence of such events. Reported adverse events related to blue-light filtering lenses were infrequent, but included increased depressive symptoms, headache, discomfort wearing the glasses, and lower mood. Adverse events associated with non-blue-light filtering lenses were occasional hyperthymia, and discomfort wearing the spectacles. We were unable to determine whether blue-light filtering lenses affect contrast sensitivity, colour discrimination, discomfort glare, macular health, serum melatonin levels or overall patient visual satisfaction, compared to non-blue-light filtering lenses, as none of the studies evaluated these outcomes.

AUTHORS' CONCLUSIONS

This systematic review found that blue-light filtering spectacle lenses may not attenuate symptoms of eye strain with computer use, over a short-term follow-up period, compared to non-blue-light filtering lenses. Further, this review found no clinically meaningful difference in changes to CFF with blue-light filtering lenses compared to non-blue-light filtering lenses. Based on the current best available evidence, there is probably little or no effect of blue-light filtering lenses on BCVA compared with non-blue-light filtering lenses. Potential effects on sleep quality were also indeterminate, with included trials reporting mixed outcomes among heterogeneous study populations. There was no evidence from RCT publications relating to the outcomes of contrast sensitivity, colour discrimination, discomfort glare, macular health, serum melatonin levels, or overall patient visual satisfaction. Future high-quality randomised trials are required to define more clearly the effects of blue-light filtering lenses on visual performance, macular health and sleep, in adult populations.

The Effect of Blue-Light Filtering Intraocular Lenses on the Development and Progression of Glaucoma

PRCIS

Among patients who underwent uneventful cataract surgery, an advantage was seen to blue-light filtering (BLF) intraocular lenses (IOLs) in terms of glaucoma-free survival and glaucoma procedure-free survival. Among patients with preexisting glaucoma, no advantage was seen.

PURPOSE

To assess the effect of BLF IOLs on the development and progression of glaucoma after cataract surgery.

PATIENTS AND METHODS

A retrospective cohort study of patients who underwent uneventful cataract surgery between 2007 and 2018 at Kymenlaakso Central Hospital, Finland. Survival analyses for the overall risk of developing glaucoma or undergoing glaucoma procedures were assessed between patients who received a BLF IOL (SN60WF) and a non-BLF IOL (ZA9003 and ZCB00). A separate analysis was performed on patients with preexisting glaucoma.

RESULTS

Included 11,028 eyes of 11,028 patients with a mean age of 75 ± 9 years (62% females). The BLF IOL was used in 5188 eyes (47%) and the non-BLF IOL in 5840 eyes (53%). During the follow-up (mean: 55 ± 34 mo), 316 cases of glaucoma were diagnosed. Glaucoma-free survival rates showed an advantage to the BLF IOL ( P = 0.036). In a Cox regression analysis controlling for age and sex the use of a BLF IOL was again associated with a lower ratio of glaucoma development (hazard ratio:0.778; 95% CI: 0.621-0.975). Furthermore, glaucoma procedure-free survival analysis revealed an advantage to the BLF IOL (hazard ratio:0.616; 95% CI: 0.406-0.935). Among 662 cases, which already had glaucoma at the time of surgery, no significant differences were seen in any outcome.

CONCLUSIONS

Among a large cohort of patients who underwent cataract surgery, the use of BLF IOLs was associated with favorable glaucoma outcomes compared with the use of non-BLF IOLs. Among patients with preexisting glaucoma, no significant advantage was seen.

Faricimab for the Treatment of Diabetic Macular Edema and Neovascular Age-Related Macular Degeneration

Nowadays; intravitreal anti-vascular endothelial growth factor (VEGF) drugs are considered the first-line therapeutic strategy for treating macular exudative diseases; including wet age-related macular degeneration (w-AMD) and diabetic macular edema (DME). Despite the important clinical achievements obtained by anti-VEGF drugs in the management of w-AMD and DME; some limits still remain; including high treatment burden; the presence of unsatisfactory results in a certain percentage of patients and long-term visual acuity decline due to complications such as macular atrophy and fibrosis. Targeting the angiopoietin/Tie (Ang/Tie) pathway beyond the VEGF pathway may be a possible therapeutic strategy; which may has the potential to solve some of the previous mentioned challenges. Faricimab is a new; bispecific antibody targeting both VEGF-A and the Ang-Tie/pathway. It was approved by FDA and; more recently; by EMA for treating w-AMD and DME. Results from phase III trials TENAYA and LUCERNE (w-AMD) and RHINE and YOSEMITE (DME) have shown the potential of faricimab to maintain clinical efficacy with more prolonged treatment regimens compared to aflibercept (12 or 16 weeks) with a a good safety profile.

TFOS Lifestyle: Impact of the digital environment on the ocular surface

Eye strain when performing tasks reliant on a digital environment can cause discomfort, affecting productivity and quality of life. Digital eye strain (the preferred terminology) was defined as "the development or exacerbation of recurrent ocular symptoms and/or signs related specifically to digital device screen viewing". Digital eye strain prevalence of up to 97% has been reported, due to no previously agreed definition/diagnostic criteria and limitations of current questionnaires which fail to differentiate such symptoms from those arising from non-digital tasks. Objective signs such as blink rate or critical flicker frequency changes are not 'diagnostic' of digital eye strain nor validated as sensitive. The mechanisms attributed to ocular surface disease exacerbation are mainly reduced blink rate and completeness, partial/uncorrected refractive error and/or underlying binocular vision anomalies, together with the cognitive demand of the task and differences in position, size, brightness and glare compared to an equivalent non-digital task. In general, interventions are not well established; patients experiencing digital eye strain should be provided with a full refractive correction for the appropriate working distances. Improving blinking, optimizing the work environment and encouraging regular breaks may help. Based on current, best evidence, blue-light blocking interventions do not appear to be an effective management strategy. More and larger clinical trials are needed to assess artificial tear effectiveness for relieving digital eye strain, particularly comparing different constituents; a systematic review within the report identified use of secretagogues and warm compress/humidity goggles/ambient humidifiers as promising strategies, along with nutritional supplementation (such as omega-3 fatty acid supplementation and berry extracts).

Blue Light Exposure: Ocular Hazards and Prevention-A Narrative Review

INTRODUCTION

Exposure to blue light has seriously increased in our environment since the arrival of light emitting diodes (LEDs) and, in recent years, the proliferation of digital devices rich in blue light. This raises some questions about its potential deleterious effects on eye health. The aim of this narrative review is to provide an update on the ocular effects of blue light and to discuss the efficiency of methods of protection and prevention against potential blue light-induced ocular injury.

METHODS

The search of relevant English articles was conducted in PubMed, Medline, and Google Scholar databases until December 2022.

RESULTS

Blue light exposure provokes photochemical reactions in most eye tissues, in particular the cornea, the lens, and the retina. In vitro and in vivo studies have shown that certain exposures to blue light (depending on the wavelength or intensity) can cause temporary or permanent damage to some structures of the eye, especially the retina. However, currently, there is no evidence that screen use and LEDs in normal use are deleterious to the human retina. Regarding protection, there is currently no evidence of a beneficial effect of blue blocking lenses for the prevention of eye diseases, in particular age-related macular degeneration (AMD). In humans, macular pigments (composed of lutein and zeaxanthin) represent a natural protection by filtering blue light, and can be increased through increased intake from foods or food supplements. These nutrients are associated with lower risk for AMD and cataract. Antioxidants such as vitamins C, E, or zinc might also contribute to the prevention of photochemical ocular damage by preventing oxidative stress.

CONCLUSION

Currently, there is no evidence that LEDs in normal use at domestic intensity levels or in screen devices are retinotoxic to the human eye. However, the potential toxicity of long-term cumulative exposure and the dose-response effect are currently unknown.

The role of the light source in antimicrobial photodynamic therapy

Antimicrobial photodynamic therapy (APDT) is a promising approach to fight the growing problem of antimicrobial resistance that threatens health care, food security and agriculture. APDT uses light to excite a light-activated chemical (photosensitiser), leading to the generation of reactive oxygen species (ROS). Many APDT studies confirm its efficacy in vitro and in vivo against bacteria, fungi, viruses and parasites. However, the development of the field is focused on exploring potential targets and developing new photosensitisers. The role of light, a crucial element for ROS production, has been neglected. What are the main parameters essential for effective photosensitiser activation? Does an optimal light radiant exposure exist? And finally, which light source is best? Many reports have described the promising antibacterial effects of APDT in vitro, however, its application in vivo, especially in clinical settings remains very limited. The restricted availability may partially be due to a lack of standard conditions or protocols, arising from the diversity of selected photosensitising agents (PS), variable testing conditions including light sources used for PS activation and methods of measuring anti-bacterial activity and their effectiveness in treating bacterial infections. We thus sought to systematically review and examine the evidence from existing studies on APDT associated with the light source used. We show how the reduction of pathogens depends on the light source applied, radiant exposure and irradiance of light used, and type of pathogen, and so critically appraise the current state of development of APDT and areas to be addressed in future studies. We anticipate that further standardisation of the experimental conditions will help the field advance, and suggest key optical and biological parameters that should be reported in all APDT studies. More in vivo and clinical studies are needed and are expected to be facilitated by advances in light sources, leading to APDT becoming a sustainable, alternative therapeutic option for bacterial and other microbial infections in the future.

m6A Modification-Association with Oxidative Stress and Implications on Eye Diseases

Oxidative stress (OS) refers to a state of imbalance between oxidation and antioxidation. OS is considered to be an important factor leading to aging and a range of diseases. The eyes are highly oxygen-consuming organs. Due to its continuous exposure to ultraviolet light, the eye is particularly vulnerable to the impact of OS, leading to eye diseases such as corneal disease, cataracts, glaucoma, etc. The N6-methyladenosine (m6A) modification is the most investigated RNA post-transcriptional modification and participates in a variety of cellular biological processes. In this study, we review the role of m6A modification in oxidative stress-induced eye diseases and some therapeutic methods to provide a relatively overall understanding of m6A modification in oxidative stress-related eye diseases.

Changes in Macular Thickness after Cataract Surgery in Patients with Open Angle Glaucoma

BACKGROUND

The purpose of this study was to examine the changes in IOP, total macular and RNFL, ganglion cell layer (GCL) thickness, and aqueous humour flare in open angle glaucoma (OAG) patients before and 6 months after cataract surgery.

METHODS

This was a prospective observational case-control age- and gender-matched study. Groups: 40 subjects in a controlled OAG (OAG_c) group, 20 subjects in an uncontrolled OAG (OAG_u) group, and 60 control group subjects.

EXAMINATION

complete ophthalmic evaluation, IOP measurement, anterior and posterior segment Optical Coherence Tomography (OCT), and laser flare photometry before and 6 months postoperatively.

RESULTS

Six months postoperatively IOP decreased in all groups. An increase in macular thickness was found postoperatively in all groups. Preoperative aqueous humour flare was higher in the OAG_c group than in the control group. After cataract surgery, aqueous humour flare was higher in the control group compared to the preoperative result.

CONCLUSIONS

Changes in IOP following cataract surgery were strongly negatively correlated with preoperative IOP. An increase in macular thickness was observed 6 months postoperatively in all groups. Aqueous humour flare did not differ in OAG_c and OAG_u groups pre- and postoperatively but significantly increased in the control group postoperatively.

Blue-blocking filters do not alleviate signs and symptoms of digital eye strain

CLINICAL RELEVANCE

There is some controversy about the utility of prescribing blue-blocking filters to mitigate digital eye strain. We found that using commercially available blue-blocking filters was ineffective in reducing orbicularis oculi muscle activity and visual symptomatology during a 30-min reading task from a computer screen.

BACKGROUND

There are some claims that blue-blocking (B-B) filters may be effective in reducing symptoms and signs of digital eye strain. However, recent studies have suggested that there is no sufficient evidence to support their use. This study assessed the short-term effects of a commercially available, B-B filter on orbicularis oculi (OO) muscle activity and symptoms of digital eye strain during the execution of a 30-min reading tas.

METHODS

Twenty-three healthy young adults (22.9 ± 3.2 years of age) performed two reading tasks from a computer screen with or without a B-B filter on two different days. OO muscle activity was recorded by surface electromyography 4-5, 9-10, 14-15, 19-20, 24-25 and 29-30 min into the trial. Participants reported their perceived levels of visual discomfort and activation before and after completing the reading task.

RESULTS

A Bayesian analysis favoured the null hypothesis that there was no change in OO muscle activity with or without using the B-B filter (Bayes Factor01 [BF01] = 7.08). Regarding symptomatology, the analysis favoured the time model that reading increased visual fatigue and discomfort but reduced activation levels (BF01 < 0.33 in all cases). However, our data did not support the alternative model that using B-B filter affected these visual symptoms.

CONCLUSIONS

The B-B filter did not alter OO muscle activity or visual symptomatology significantly during the execution of a 30-min reading task in asymptomatic subjects. These findings support the idea that B-B filters do not attenuate signs and symptoms of digital eye strain.

The Blue Light Hazard Versus Blue Light Hype

PURPOSE

The blue light hazard is the experimental finding that blue light is highly toxic to the retina (photic retinopathy), in brief abnormally intense exposures, including sungazing or vitreoretinal endoillumination. This term has been misused commercially to suggest, falsely, that ambient environmental light exposure causes phototoxicity to the retina, leading to age-related macular degeneration (AMD). We analyze clinical, epidemiologic, and biophysical data regarding blue-filtering optical chromophores.

DESIGN

Perspective.

METHODS

Analysis and integration of data regarding the blue light hazard and blue-blocking filters in ophthalmology and related disciplines.

RESULTS

Large epidemiologic studies show that blue-blocking intraocular lenses (IOLs) do not decrease AMD risk or progression. Blue-filtering lenses cannot reduce disability glare because image and glare illumination are decreased in the same proportion. Blue light essential for optimal rod and retinal ganglion photoreception is decreased by progressive age-related crystalline lens yellowing, pupillary miosis, and rod and retinal ganglion photoreceptor degeneration. Healthful daily environmental blue light exposure decreases in older adults, especially women. Blue light is important in dim environments where inadequate illumination increases risk of falls and associated morbidities.

CONCLUSIONS

The blue light hazard is misused as a marketing stratagem to alarm people into using spectacles and IOLs that restrict blue light. Blue light loss is permanent for pseudophakes with blue-blocking IOLs. Blue light hazard misrepresentation flourishes despite absence of proof that environmental light exposure or cataract surgery causes AMD or that IOL chromophores provide clinical protection. Blue-filtering chromophores suppress blue light critical for good mental and physical health and for optimal scotopic and mesopic vision.

Effect of Blue Light Filters on Tear and Contrast Sensitivity in Individuals Using Electronic Devices

OBJECTIVES

To investigate the effect of contact lenses with blue light filters on contrast sensitivity and any alteration in tear quantity and quality.

METHODS

This prospective longitudinal pilot study required three visits by each participant. Monocular visual acuity, contrast sensitivity, phenol red thread test, and tear breakup time were measured at each visit.

RESULTS

There were significant differences in logarithmic contrast sensitivity between the groups. The breakup time (BUT) was significantly lower after using video display terminals than before (P<0.05). No differences in BUT were found between groups video display terminals and contact lenses having the blue filter (P>0.05). However, higher mean values were observed in the group after video display terminal use with contact lenses having the blue filter than that with standard contact lenses (P>0.05 in both groups). Furthermore, the mean value of phenol red thread test on the group after video display terminal use with contact lenses having the blue filter was lower than the group before its use (P>0.05).

CONCLUSION

The results establish a possible relationship between tear stability, improved contrast sensitivity, and the use of a blue filter in contact lenses.

Animal Models of LED-Induced Phototoxicity. Short- and Long-Term In Vivo and Ex Vivo Retinal Alterations

Phototoxicity animal models have been largely studied due to their degenerative communalities with human pathologies, e.g., age-related macular degeneration (AMD). Studies have documented not only the effects of white light exposure, but also other wavelengths using LEDs, such as blue or green light. Recently, a blue LED-induced phototoxicity (LIP) model has been developed that causes focal damage in the outer layers of the superior-temporal region of the retina in rodents. In vivo studies described a progressive reduction in retinal thickness that affected the most extensively the photoreceptor layer. Functionally, a transient reduction in a- and b-wave amplitude of the ERG response was observed. Ex vivo studies showed a progressive reduction of cones and an involvement of retinal pigment epithelium cells in the area of the lesion and, in parallel, an activation of microglial cells that perfectly circumscribe the damage in the outer retinal layer. The use of neuroprotective strategies such as intravitreal administration of trophic factors, e.g., basic fibroblast growth factor (bFGF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF) or pigment epithelium-derived factor (PEDF) and topical administration of the selective alpha-2 agonist (Brimonidine) have demonstrated to increase the survival of the cone population after LIP.

Prevention of the Onset of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) represents the leading cause of irreversible blindness in elderly people, mostly after the age of 65. The progressive deterioration of visual function in patients affected by AMD has a significant impact on quality of life and has also high social costs. The current therapeutic options are only partially able to slow down the natural course of the disease, without being capable of stopping its progression. Therefore, better understanding of the possibilities to prevent the onset of the disease is needed. In this regard, a central role is played by the identification of risk factors, which might participate to the development of the disease. Among these, the most researched are dietary risk factors, lifestyle, and light exposure. Many studies showed that a higher dietary intake of nutrients, such as lutein, zeaxanthin, beta carotene, omega-3 fatty acids and zinc, reduced the risk of early AMD. Regarding lifestyle habits, the association between smoking and AMD is currently accepted. Finally, retinal damage caused by ultraviolet rays and blue light is also worthy of attention. The scope of this review is to summarize the present knowledge focusing on the measures to adopt in order to prevent the onset of AMD.

Effect of Blue Light Filtering Intraocular Lenses on Visual Perception

Background and Objectives: This retrospective consecutive case control study compares best-corrected visual acuity (BCVA), mesopic contrast sensitivity (CS), color vision, and glare between a group of eyes with blue-light-filtering intraocular lenses and another with UV-light-filtering intraocular lenses. Materials and Methods: We used Early Treatment Diabetic Retinopathy Study charts to compare BCVA, Rabin charts for mesopic CS testing, Oculus HMC Anomaloscope MR to test for chromatic discrimination, and Oculus Mesotest II to measure scotopic CS with glare. For analysis, we used descriptive statistics and compared means with parametric and non-parametric tests. The level of significance was set as α = 0.05. Results: For the group with the blue-light-filtering intraocular lens, the average results were BCVA = 0.96 (SD ± 0.09), CS = 1.78 log (SD ± 0.12), chromatic discrimination results M = 63.91 (SD ± 11.88), R = 60.07 (SD ± 7.89). For mesopic CS with glare, the group achieved on average 2.54 (SD ± 1.50) points out of 4. For the group with the UV-light-filtering intraocular lens, the average results were BCVA = 0.93 (SD ± 0.14), CS = 1.79 log (SD ± 0.13), chromatic discrimination results M = 65.38 (SD ± 17.14), R = 60.79 (SD ± 10.39). For mesopic CS with glare, this group achieved an average of 2.79 (SD ± 1.53) points out of 4. Conclusion: No significant differences (p > 0.05) were found in any of the tested parameters between the analyzed groups. Slight shift in color vision was observed, although not statistically significant.

Blue light filtering ophthalmic lenses: A systematic review

Background: Blue blocking (BB) lenses, including spectacles and intraocular lenses, work by attenuating short-wavelength light. BB glasses are being marketed with the aim to reduce eye fatigue symptoms when using digital devices, improve sleep quality and potentially confer protection from retinal phototoxicity. BB intraocular lenses following cataract surgery may be implanted because they are thought to prevent age-related macular degeneration (AMD) progression.Methods: The present study is a systematic review aiming to analyze BB lenses clinical efficacy in preventing blue light-related ocular disorders, including AMD progression, eye fatigue, and their impact on sleep quality. We searched Medline, PubMed, Web of Science and the Cochrane Library until May 2020.Results:Although several studies have been performed investigating BB lenses, clinical efficacy for preventing or attenuating the above-mentioned ocular disorders is often theorical or based on laboratory or animal experiments. Conclusions: To date, there is a lack of consistent evidence for a larger-sclale introduction of BB lenses in the routine clinical practice.

Visible light. Part II: Photoprotection against visible and ultraviolet light

Cutaneous photobiology studies have focused primarily on the ultraviolet portion of the solar spectrum. Visible light (VL), which comprises 50% of the electromagnetic radiation that reaches the Earth's surface and, as discussed in Part I of this CME, has cutaneous biologic effects, such as pigment darkening and erythema. Photoprotection against VL includes avoiding the sun, seeking shade, and using photoprotective clothing. The organic and inorganic ultraviolet filters used in sunscreens do not protect against VL, only tinted sunscreens do. In the United States, these filters are regulated by the Food and Drug Administration as an over-the-counter drug and are subject to more stringent regulations than in Europe, Asia, and Australia. There are no established guidelines regarding VL photoprotection. Alternative measures to confer VL photoprotection are being explored. These novel methods include topical, oral, and subcutaneous agents. Further development should focus on better protection in the ultraviolet A1 (340-400 nm) and VL ranges while enhancing the cosmesis of the final products.

Faricimab: an investigational agent targeting the Tie-2/angiopoietin pathway and VEGF-A for the treatment of retinal diseases

INTRODUCTION

Intravitreal antivascular endothelial growth factor (VEGF) drugs represent the first-line treatment option for wet age-related macular degeneration (w-AMD) and diabetic macular edema (DME); however, the frequent injection intervals have illuminated to the necessity for new molecules allowing a more prolonged treatment regimen. Faricimab is a promising bispecific drug targeting VEGF-A and the Ang-Tie/pathway. Phase II STAIRWAY and AVENUE Trials showed its clinical efficacy for the treatment of w-AMD, while the phase II BOULEVARD Trial revealed its superiority to monthly ranibizumab in the management of DME with a monthly treatment regimen. The agents are awaiting approval for the treatment of w-AMD and DME.

AREAS COVERED

This article presents an overview of w-AMD and diabetic retinopathy and examines the progress of Faricimab through clinical trials. It offers insights on where Faricimab may be placed in the future market of anti-VEGF treatments and discusses the role of Ang/Tie pathway as a potential additive weapon for the treatment of w-AMD, DME, and retinal vein occlusion (RVO).

EXPERT OPINION

The possibility of administering faricimab with more prolonged treatment intervals represents an important advantage to decrease the treatment burden and improve patient compliance. Further phase III trials should provide more evidence on clinical efficacy.

Treatment of age-related macular degeneration after cataract surgery: a study from the Swedish National Cataract and Macula Registers

PURPOSE

To characterize pre- and perioperative factors associated with treatment for wet age-related macular degeneration (wet AMD) after cataract surgery.

METHODS

This register-based cohort study with data from the Swedish National Cataract Register (NCR) and the Swedish Macula Register (SMR) from 2010 to 2017 compared eyes with and without preoperative AMD that had undergone cataract surgery and was subsequently treated for wet AMD to eyes not treated within the study period. All first-eye surgeries registered in the NCR from 2010 to 2017 and matching eyes found in the SMR that had undergone treatment for wet AMD ≥ 1 year after the cataract procedure were included. Data for cataract surgery date, age and gender, use of a blue-blocking IOL, preoperative visual acuity, ocular comorbidities, posterior capsule rupture and date of AMD treatment initiation were extracted.

RESULTS

The only independent factor associated with postoperative treatment of wet AMD in both groups was female gender (67.3% vs. 58.8%, p < 0.001 and 66.4% vs. 60.6%, p = 0.001, respectively). Older age was an independent factor in eyes without preoperative AMD (78.4 ± 6.5 vs. 73.4 ± 9.6 years, p < 0.001). A blue-blocking IOL appeared to decrease the likelihood of subsequent wet AMD treatment slightly but not statistically significant in eyes with preoperative AMD (52.7% vs. 56.8%, p = 0.110).

CONCLUSIONS

Some factors (female gender, high age) are associated with undergoing subsequent treatment for wet AMD to a higher extent. If the use of a blue-blocking IOL offers any protection from undergoing AMD treatment after cataract surgery, such an effect must be very small.

Effects of a blue-blocking screen filter on accommodative accuracy and visual discomfort

INTRODUCTION

The prescription of blue-blocking (B-B) filters for the management of visual symptoms and signs associated with the use of electronic devices is routinely performed by eye care specialists. However, the utility of B-B filters is a matter of debate and discussion by the scientific community due to the lack of evidence supporting their use. Here, we aimed to determine the effects of using B-B filters on the dynamics of the accommodative response and pupil size and perceived levels of visual discomfort, while performing a 30-min reading task at a close distance in subjects who routinely use electronic devices.

METHODS

Nineteen healthy young adults (22.0 ± 2.7 years) read two 30-min passages on a computer screen placed at 50 cm, either while using a commercially available B-B filter or without any filter on two different days. The magnitude and variability of both the accommodative response and pupil size were dynamically measured for 60 s using the WAM-5500 open field autorefractometer at 4-5, 9-10, 14-15, 19-20, 24-25, and 29-30 min into the trial. The perceived levels of visual discomfort were also obtained.

RESULTS

The lag and variability of accommodation were insensitive to the blue light level (p = 0.34 and 0.62, respectively). There was a time-on-task effect for the variability of accommodation, showing greater instability over time regardless of the blue light level. The use of the B-B filter was associated with improved reading speed (p = 0.02), with an increase of 16.5 words per minute. However, it was not associated with any significant change in pupil dynamics or the perceived levels of visual discomfort (p> 0.05 in both cases).

CONCLUSIONS

Our data showed that the use of a B-B filter had no effect on accommodative dynamics or visual symptomatology. Based on these findings, there is no support for the prescription of B-B filters to attenuate the visual symptoms and signs associated with the use of electronic devices in healthy young adults.

Effects of the Emitted Light Spectrum of Liquid Crystal Displays on Light-Induced Retinal Photoreceptor Cell Damage

Liquid crystal displays (LCDs) are used as screens in consumer electronics and are indispensable in the modern era of computing. LCDs utilize light-emitting diodes (LEDs) as backlight modules and emit high levels of blue light, which may cause retinal photoreceptor cell damage. However, traditional blue light filters may decrease the luminance of light and reduce visual quality. We adjusted the emitted light spectrum of LED backlight modules in LCDs and reduced the energy emission but maintained the luminance. The 661W photoreceptor cell line was used as the model system. We established a formula of the ocular energy exposure index (OEEI), which could be used as the indicator of LCD energy emission. Cell viability decreased and apoptosis increased significantly after exposure to LCDs with higher emitted energy. Cell damage occurred through the induction of oxidative stress and mitochondrial dysfunction. The molecular mechanisms included activation of the NF-κB pathway and upregulation of the expression of proteins associated with inflammation and apoptosis. The effect was correlated with OEEI intensity. We demonstrated that LCD exposure-induced photoreceptor damage was correlated with LCD energy emission. LCDs with lower energy emission may, therefore, serve as suitable screens to prevent light-induced retinal damage and protect consumers’ eye health.