Influence of Blue-Light-Filtering Intraocular Lenses on Color Perception and Contrast Acuity

Blue Light and Digital Screens Revisited: A New Look at Blue Light from the Vision Quality, Circadian Rhythm and Cognitive Functions Perspective

Research conducted over the years has established that artificial light at night (ALAN), particularly short wavelengths in the blue region (~400-500 nm), can disrupt the circadian rhythm, cause sleep disturbances, and lead to metabolic dysregulation. With the increasing number of people spending considerable amounts of time at home or work staring at digital screens such as smartphones, tablets, and laptops, the negative impacts of blue light are becoming more apparent. While blue wavelengths during the day can enhance attention and reaction times, they are disruptive at night and are associated with a wide range of health problems such as poor sleep quality, mental health problems, and increased risk of some cancers. The growing global concern over the detrimental effects of ALAN on human health is supported by epidemiological and experimental studies, which suggest that exposure to ALAN is associated with disorders like type 2 diabetes, obesity, and increased risk of breast and prostate cancer. Moreover, several studies have reported a connection between ALAN, night-shift work, reduced cognitive performance, and a higher likelihood of human errors. The purpose of this paper is to review the biological impacts of blue light exposure on human cognitive functions and vision quality. Additionally, studies indicating a potential link between exposure to blue light from digital screens and increased risk of breast cancer are also reviewed. However, more research is needed to fully comprehend the relationship between blue light exposure and adverse health effects, such as the risk of breast cancer.

[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.

Association of clear vs blue-light filtering intraocular lenses with mental and behavioral disorders and diseases of the nervous system among patients receiving bilateral cataract surgery

PURPOSE

To analyze new-onset mental and behavioral disorders and nervous system diseases in patients with cataract implanted with either non-blue-light filtering (BLF) or BLF intraocular lenses (IOLs) in both eyes.

SETTING

Department of Ophthalmology, Kymenlaakso Central Hospital, Kotka, Finland.

DESIGN

A retrospective registry-based cohort study of patients operated between September 2007 and December 2018 who were followed until December 2021. We included 4986 patients who underwent bilateral cataract surgery.

METHODS

Patients were implanted with either non-BLF IOLs (N = 2609) or BLF IOLs (N = 2377) in both eyes. Follow-up before the first-eye surgery and between the first-eye and the second-eye surgery was performed to acknowledge the preexisting disorders and diseases. After the second-eye surgery, the groups were analyzed for the new-onset mental and behavioral disorders and diseases of the nervous system subcategorized by the International Classification of Diseases codes.

RESULTS

1707 male and 3279 female patients, aged 73.2 ± 8.6 years at the first-eye surgery and 74.3 ± 8.8 years at the second-eye surgery, were identified. In univariate log-rank tests, the use of BLF IOLs showed no association in overall new-onset disorders or diseases over non-BLF IOLs, in any subtype diagnosis codes except for sleep disorders, which favored BLF IOLs ( P = .003). A multivariate analysis adjusted for age and sex identified no associations in any new-onset disorders or diseases. Multivariate analysis of sleep disorders showed a nonsignificant advantage for BLF-IOLs (hazard ratio 0.756, 95% CI 0.534-1.070, P = .114).

CONCLUSIONS

BLF IOLs were not associated with mental and behavioral disorders or diseases of the nervous system.

Clinical Evaluation of a Modified Light Transmission Short-Wavelength Filtering Intraocular Lens Compared to a Colorless Control

INTRODUCTION

The aim of this study was to evaluate the safety and efficacy of a violet-light filtering intraocular lens (IOL) compared to a colorless IOL control.

METHODS

This was a prospective, bilateral, randomized, comparative, patient/evaluator-masked multi-center clinical trial at 12 sites in the USA. Patients underwent standard small-incision phacoemulsification cataract extraction. Visual acuity, contrast sensitivity, and color vision were tested 12 months postoperatively. Patient satisfaction and vision-related quality of life were evaluated based on directed patient responses obtained from a binocular subjective questionnaire.

RESULTS

A total of 250 subjects were bilaterally implanted with the violet-light filtering TECNIS monofocal ZV9003 (n = 126) and colorless TECNIS monofocal ZA9003 (n = 124). Mean uncorrected distance visual acuity (UDVA) was 0.123 LogMAR for ZV9003 and 0.116 LogMAR for the ZA9003 group. Mean corrected distance visual acuity (CDVA) was 0.00 LogMAR for both groups. No significant difference was found between the groups for 22/25 questionnaire categories, including color perception. A significant difference was found in favor of the ZV9003 group for day driving, night driving, and frustration with vision. Contrast sensitivity mean difference was < 0.05 log units across all lighting conditions and spatial frequencies.

CONCLUSION

No difference was found between groups for visual acuity, contrast sensitivity, color testing, and adverse events as well as with the majority of optical/visual symptoms. A statistical difference was noted in driving and frustration with eyesight that may be related to benefits of using a violet-light filtering chromophore. Overall, the violet-light filtering ZV9003 showed excellent visual acuity and contrast sensitivity results with a low incidence of optical/visual symptoms.

Association of Blue Light-Filtering Intraocular Lenses With All-Cause and Traffic Accident-Related Injuries Among Patients Undergoing Bilateral Cataract Surgery in Finland

IMPORTANCE

Blue light-filtering (BLF) intraocular lenses (IOLs) have been widely used in clinical practice for more than 20 years and have been implanted in millions of patients with cataracts worldwide. However, little evidence on the association of BLF IOLs with injuries is available.

OBJECTIVE

To assess the association of BLF IOLs with all-cause and traffic accident-related injuries and quality of vision while driving after bilateral cataract surgery.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective registry-based cohort study included patients who underwent bilateral cataract surgery between September 3, 2007, and December 14, 2018, and were followed until December 14, 2021. Surgery was performed at the Department of Ophthalmology, Kymenlaakso Central Hospital, Kotka, Finland. The 4986 participants received non-BLF IOLs (n = 2609) or BLF IOLs (n = 2377) in both eyes. Patients undergoing bilateral surgery between 2015 to 2016 with non-BLF IOLs (n = 102) or BLF IOLs (n = 91) and currently driving a car were interviewed using a structured questionnaire for visual performance while driving.

EXPOSURES

Follow-up for a mean (SD) of 2166 (1110) days after second eye surgery.

MAIN OUTCOMES AND MEASURES

Kaplan-Meier and multivariable Cox proportional hazards regression analyses for the risk of all-cause and traffic accident-related injuries after surgery in the second eye obtained from the patient medical records were assessed. To improve follow-up precision, both death and the end of the follow-up were used as censoring events.

RESULTS

A total of 4986 patients were included in the analysis (1707 [34.2%] men and 3279 [65.8%] women; mean [SD] age, 73.2 [8.6] years at the first surgery and 74.3 [8.8] years at the second). Injury-free survival rates preceding the first eye surgery were comparable between the non-BLF and BLF IOL groups (hazard ratio adjusted for age and sex, 0.95 [95% CI, 0.81-1.13; P = .57]). In multivariable Cox proportional hazards regression analysis controlling for age and sex, the use of BLF IOLs showed no advantage in overall injuries compared with the use of non-BLF IOLs (hazard ratio, 0.99 [95% CI, 0.88-1.11]; P = .85) or in any injury subtype. Subjective visual performance parameters for driving were all comparable between the non-BLF and BLF IOL groups except for glare when driving in the dark (evening or night), which occurred among 9 of 80 patients with BLF IOLs compared with 0 of 83 non-BLF IOLs (P < .001).

CONCLUSIONS AND RELEVANCE

The findings of this cohort study suggest that use of BLF IOLs was not associated with reduced risk of injuries, whereas glare during nighttime driving was significantly worse in the BLF IOL group with pseudophakia.

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.

The Influence of Intraocular Lenses (IOLs) on the Properties of Filters Protecting Human Eyes against Optical Radiation in the Work Environment

Under the specific illumination conditions of many workplaces, e.g., in the metallurgical industry, decreased lighting may impair workers’ vision and, as a result, their productivity. Spectrophotometric tests of two types of protective optical filters (welding filters and infrared protection filters), two types of intraocular lenses (IOLs with and without yellow chromophore), and filter-IOL systems were carried out. In spectrophotometric studies, the spectral characteristics of transmission and the coefficients for the assessment of light transmission were determined. This study explores the relationship between the eye protection levels offered by filters and the use of intraocular lenses (IOLs), and especially those containing a yellow chromophore which may lower the luminous transmittance of protective filters. In our previous works, we studied a large number of optical protective filters and many factors influencing their performance. A review of the literature has shown the absence of prior research on the subject. For this purpose, transmittance reduction factors were defined for the evaluation of the filter-IOL system. The spectral characteristics of luminous transmittance for the tested IOLs indicate a significant decrease of transmittance for those with yellow chromophore within the range up to approx. 475 nm, as compared to IOLs without chromophore. The main objective of this study was to determine whether people with IOLs need different protective filters against harmful optical radiation as well as whether IOLs may change the required category of protective filters. The key finding is that while the use of IOLs in conjunction with protective filters does change the light transmission coefficient, it does not affect the filter protection levels. The transmittance reduction factors were similar (0.95 to 0.99 relative units) for all filter-IOL systems irrespective of the presence or absence of yellow chromophore. It must be said clearly that, in reference to the requirements specified in the standards, IOLs did not affect the filter protection levels. This means that the quality of vision did not change significantly when using the analyzed filters and IOLs.

The Effects of a Blue-Light Filtering Versus Clear Intraocular Implant on Color Appearance

Purpose

More than a dozen studies have investigated whether blue-light filtering (BLF) intraocular lens (IOL) implants influence color vision, generally finding they do not. These studies have not tested color vision per se; rather, they have measured color vision deficiencies or chromatic discrimination. Here, we used additive trichromatic colorimetry to assess color appearance in participants with BLF and clear IOL.

Methods

Seventy-six participants were recruited from two populations: older participants (n = 52) with BLF and clear IOL (n = 98 eyes; M = 67.33 ± 7.48 years; 58.8% female; 25.5% non-White), and young adult control participants (n = 24; M = 21.0 ± 5.13 years; 70.8% female; 41.5% non-White). Participants used a custom-built tricolorimeter to mix three primaries until a perceived perfect neutral white was achieved. Color appearance, expressed as chromaticity coordinates, was measured with a spectral radiometer (ILS950).

Results

Between subjects, the BLF IOL chromaticity coordinates (x = 0.34, y = 0.35, u′ = 0.21, v′ = 0.48) were not significantly different from the clear IOL (x = 0.34, y = 0.33, u′ = 0.22, v′ = 0.48). BLF and clear IOL were also not different within-contralateral subjects (n = 21; BLF x = 0.34, y = 0.33, u′ = 0.22, v′ = 0.47; clear x = 0.34, y = 0.33, u′ = 0.21, v′ = 0.48). Both IOL groups differed from young adults (v′[0.45; P = 0.001], x[0.31; P = 0.008], and y[ 0.30, P < 0.000], but not u′[0.21]).

Conclusions

One advantage of geometric representation of color space is the ability to specify the appearance (rather than spectral composition) of any light mixture by specific coordinates. Using this system, only minor differences in color appearance were found between a BLF, clear IOL, and young natural lens.

Translational Relevance

When color perception is directly measured, the BLF and clear IOL are not meaningfully different.

The effect of blue light filtering lenses on speed perception

Blue-light filtering lenses (BFLs) are marketed to protect the eyes from blue light that may be hazardous to the visual system. Because BFLs attenuate light, they reduce object contrast, which may impact visual behaviours such as the perception of object speed which reduces with contrast. In the present study, we investigated whether speed perception is affected by BFLs. Using a two-interval forced-choice procedure in conjunction with Method of Constant Stimuli, participants (n = 20) judged whether the perceived speed of a moving test stimulus (1.5–4.5°/s) viewed through a BFL was faster than a reference stimulus (2.75°/s) viewed through a clear lens. This procedure was repeated for 3 different BFL brands and chromatic and achromatic stimuli. Psychometric function fits provided an estimate of the speed at which both test and reference stimuli were matched. We find that the perceived speed of both chromatic and achromatic test stimuli was reduced by 6 to 20% when viewed through BFLs, and lenses that attenuated the most blue-light produced the largest reductions in perceived speed. Our findings indicate that BFLs whilst may reduce exposure to hazardous blue light, have unintended consequences to important visual behaviours such as motion perception.

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.

Effect of blue-blocking lenses on colour discrimination

CLINICAL RELEVANCE

Tinted lenses may adversely affect colour discrimination. Before recommending tinted lenses to patients, practitioners should bear in mind any effects on colour discrimination. The effects of 'blue-blocking' spectacle lenses with high luminous transmittance on colour vision is not a concern.

BACKGROUND

Blue-blocking lenses have been widely promoted by manufacturers and practitioners. The more blue-blocking lenses are known to affect colour vision significantly but there has been no study of the effects of 'blue-blocking' spectacle lenses.

METHODS

The transmittances of commercially available lenses were measured and the three lenses with the lowest blue light transmittance were selected. Subjects undertook the following computer-based colour vision tests: Colour Assessment and Diagnosis; the Cambridge Colour Test; and the Farnsworth-Munsell 100 Hue Test.

RESULTS

Blue and luminous transmittances of lenses were documented. The reduction in blue transmittance varied from 12 to 40 per cent (two to 30 per cent compared with an untinted lens). The lenses were found to have no significant, statistical or possibly practical, effect on the results of the three colour vision tests (t-test, analysis of variance, Mann-Whitney, Kruskal-Wallis).

CONCLUSION

The modest blue light transmittance reduction of the 'blue-blocking' spectacle lenses examined was not sufficient to have a statistically significant effect on colour vision.

The Effect of Blue-blocking Lenses on Photostress Recovery Times

SIGNIFICANCE

The selective reduction in visible wavelengths transmitted through commercially available blue-blocking lenses (BBLs) is known to influence the appearance and contrast detection of objects, particularly at low light levels. This influence may impair the human retinal receptor response time to dynamic light changes during photostress events.

PURPOSE

This study aimed to assess whether BBLs selectively affect photostress recovery times (PSRTs) for chromatic and achromatic stimuli of different Weber contrasts that were viewed on a dark black background.

METHODS

Photostress recovery times were measured in 12 younger participants (18 to 39 years old) with no history of ocular disease or abnormal vision. Photostress recovery times were evaluated for four brands of BBLs, which were compared with a control lens. In these experiments, after exposure to an intense light source for 5 seconds, the time taken to recover vision and correctly identify a computer-generated letter stimulus viewed under low and high luminance levels was determined, which means perception is likely to be governed by mesopic and photopic conditions. Across conditions, the letter stimulus was achromatic and chromatic and could differ in luminance contrast.

RESULTS

Under photopic stimulus conditions, although reducing luminance contrast increased PSRTs, BBLs had no significant effect on PSRTs relative to control lens. However, under mesopic stimulus conditions, BBLs significantly affect PSRTs for both achromatic (F2.006,8.02 = 61.95, P < .0001) and chromatic stimuli (F3,16 =139.01, P < .0001), particularly for blue targets, which had considerably longer PSRTs (38.40 seconds). The brand of BBL was also shown to selectively affect PSRTs, with those with transmittance profiles that block the most blue light having longer PSRTs.

CONCLUSIONS

The present study suggests that, although the color and contrast of the target stimuli affected recovery times, the difference in recovery times between different types of BBLs was noticed only under low-light-level stimulus conditions.

Blue-light filtering intraocular lenses (IOLs) for protecting macular health

BACKGROUND

An intraocular lens (IOL) is a synthetic lens that is surgically implanted within the eye following removal of the crystalline lens, during cataract surgery. While all modern IOLs attenuate the transmission of ultra-violet (UV) light, some IOLs, called blue-blocking or blue-light filtering IOLs, also reduce short-wavelength visible light transmission. The rationale for blue-light filtering IOLs derives primarily from cell culture and animal studies, which suggest that short-wavelength visible light can induce retinal photoxicity. Blue-light filtering IOLs have been suggested to impart retinal protection and potentially prevent the development and progression of age-related macular degeneration (AMD). We sought to investigate the evidence relating to these suggested benefits of blue-light filtering IOLs, and to consider any potential adverse effects.

OBJECTIVES

To assess the effects of blue-light filtering IOLs compared with non-blue-light filtering IOLs, with respect to providing protection to macular health and function.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 9); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the ICTRP. The date of the search was 25 October 2017.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), involving adult participants undergoing cataract extraction, where a blue-light filtering IOL was compared with an equivalent non-blue-light filtering IOL.

DATA COLLECTION AND ANALYSIS

The prespecified primary outcome was the change in distance best-corrected visual acuity (BCVA), as a continuous outcome, between baseline and 12 months of follow-up. Prespecified secondary outcomes included postoperative contrast sensitivity, colour discrimination, macular pigment optical density (MPOD), proportion of eyes with a pathological finding at the macula (including, but not limited to the development or progression of AMD, or both), daytime alertness, reaction time and patient satisfaction. We evaluated findings related to ocular and systemic adverse effects.Two review authors independently screened abstracts and full-text articles, extracted data from eligible RCTs and judged the risk of bias using the Cochrane tool. We reached a consensus on any disagreements by discussion. Where appropriate, we pooled data relating to outcomes and used random-effects or fixed-effect models for the meta-analyses. We summarised the overall certainty of the evidence using GRADE.

MAIN RESULTS

We included 51 RCTs from 17 different countries, although most studies either did not report relevant outcomes, or provided data in a format that could not be extracted. Together, the included studies considered the outcomes of IOL implantation in over 5000 eyes. The number of participants ranged from 13 to 300, and the follow-up period ranged from one month to five years. Only two of the studies had a trial registry record and no studies referred to a published protocol. We did not judge any of the studies to have a low risk of bias in all seven domains. We judged approximately two-thirds of the studies to have a high risk of bias in domains relating to 'blinding of participants and personnel' (performance bias) and 'blinding of outcome assessment' (detection bias).We found with moderate certainty, that distance BCVA with a blue-light filtering IOL, at six to 18 months postoperatively, and measured in logMAR, was not clearly different to distance BCVA with a non-blue-light filtering IOL (mean difference (MD) -0.01 logMAR, 95% confidence interval (CI) -0.03 to 0.02, P = 0.48; 2 studies, 131 eyes).There was very low-certainty evidence relating to any potential inter-intervention difference for the proportion of eyes that developed late-stage AMD at three years of follow-up, or any stage of AMD at one year of follow-up, as data derived from one trial and two trials respectively, and there were no events in either IOL intervention group, for either outcome. There was very low-certainty evidence for the outcome for the proportion of participants who lost 15 or more letters of distance BCVA at six months of follow-up; two trials that considered a total of 63 eyes reported no events, in either IOL intervention group.There were no relevant, combinable data available for outcomes relating to the effect on contrast sensitivity at six months, the proportion of eyes with a measurable loss of colour discrimination from baseline at six months, or the proportion of participants with adverse events with a probable causal link with the study interventions after six months.We were unable to draw reliable conclusions on the relative equivalence or superiority of blue-light filtering IOLs versus non-blue-light filtering IOLs in relation to longer-term effects on macular health. We were also not able to determine with any certainty whether blue-light filtering IOLs have any significant effects on MPOD, contrast sensitivity, colour discrimination, daytime alertness, reaction time or patient satisfaction, relative to non-blue-light filtering IOLs.

AUTHORS' CONCLUSIONS

This systematic review shows with moderate certainty that there is no clinically meaningful difference in short-term BCVA with the two types of IOLs. Further, based upon available data, these findings suggest that there is no clinically meaningful difference in short-term contrast sensitivity with the two interventions, although there was a low level of certainty for this outcome due to a small number of included studies and their inherent risk of bias. Based upon current, best-available research evidence, it is unclear whether blue-light filtering IOLs preserve macular health or alter risks associated with the development and progression of AMD, or both. Further research is required to fully understand the effects of blue-light filtering IOLs for providing protection to macular health and function.

Role of short-wavelength filtering lenses in delaying myopia progression and amelioration of asthenopia in juveniles

AIM

To evaluate the positive effects of blue-violet light filtering lenses in delaying myopia and relieving asthenopia in juveniles.

METHODS

Sixty ametropia juveniles (aged range, 11-15y) were randomized into two groups: the test group (30 children, 60 eyes), wearing blue-violet light filtering lenses; and the control group (30 children, 60 eyes), wearing ordinary aspherical lenses. Baseline refractive power of the affected eyes and axial length of the two groups was recorded. After 1-year, the patients underwent contrast sensitivity (glare and non-glare under bright and dark conditions), accommodation-related testing, asthenopia questionnaire assessment, and adverse reaction questionnaire assessment.

RESULTS

After 1y of wearing the filtering lenses, changes in refractive power and axial length were not significantly different between the two groups (P>0.05). Under bright conditions, the contrast sensitivities at low and medium-frequency grating (vision angles of 6.3°, 4.0°, and 2.5°) with glare in the test group were significantly higher than in the control group (P<0.05), while the contrast sensitivity at low-frequency grating (vision angles of 6.3° and 4.0°) in the absence of glare in the test group was higher than in the control group (P<0.05). Under glare and non-glare dark conditions, the contrast sensitivities of various frequencies in the test group did not show significant differences compared with those in the control group (P>0.05). In the test group, the amplitude of accommodation, accommodative lag, and accommodative sensitivity of patients wearing glasses for 6 and 12mo were significantly elevated (P<0.05), while the asthenopia gratings were significantly decreased (P<0.05). Nevertheless, in the control group, the amplitude of accommodation, accommodative lag, and accommodative sensitivity after 12mo were not significantly altered compared with baseline (P>0.05), and the asthenopia grating was not significantly decreased (P>0.05). In addition, after wearing glasses for 6 to 12mo, the asthenopia grating of patients in the test group decreased significantly compared with the control group (P<0.05). At 12mo, the constituent ratio of adverse reactions did not show significant difference between the two groups (P>0.05).

CONCLUSION

A 1-year follow-up reveal that compare with ordinary glasses, short-wavelength filtering lenses (blue/violet-light filters) increase the low- and medium-frequency contrast sensitivity under bright conditions and improved accommodation. They effectively relieved asthenopia without severe adverse reactions, suggesting potential for clinical application. However, no significant advantages in terms of refractive power or axial length progression were found compared with ordinary aspheric lenses.

Psychophysical Measurements of Luminance Contrast Sensitivity and Color Discrimination with Transparent and Blue-Light Filter Intraocular Lenses

Introduction

The purpose of this study was to measure luminance contrast sensitivity and color vision thresholdfs in normal subjects using a blue light filter lens and transparent intraocular lens material.

Methods

Monocular luminance grating contrast sensitivity was measured with Psycho for Windows (version 2.36; Cambridge Research Systems) at 3.0, 6.0, 12.0, 20.0, and 30.0 cycles per degree of visual angle (cpd) in 15 normal subjects (eight female), with a mean age of 21.6 years (SD = 3.8 years). Chromatic discrimination was assessed with the Cambridge colour test (CCT) along the protan, deutan, and tritan color confusion axes. Both tests were performed in a darkened room under two situations: with a transparent lens and with blue light filter lens. Subjective impressions were taken by subjects regarding their visual experience under both conditions.

Results

No difference was found between the luminance contrast sensitivity measured with transparent and blue light filter. However, 13/15 (87%) of the subjects reported more comfortable vision with the blue filter. In the color vision test, tritan thresholds were significantly higher for the blue filter compared with the transparent filter (p = 0.003). For protan and deutan thresholds no differences were found.

Conclusion

Blue-yellow color vision is impaired with the blue light filter, and no impairment occurs with the transparent filter. No significant differences in thresholds were found in the luminance contrast sensitivity comparing the blue light and transparent filters. The impact of short wavelength light filtering on intrinsically photosensitive retinal ganglion cells is also discussed.

Optimizing cataract surgery in patients with age-related macular degeneration

Age-related macular degeneration (AMD) is one of the leading causes of visual impairment. The development of cataract in AMD patients poses challenges in assessing timing of surgery, predicting potential benefit to the patient of surgery, and predicting short- and long-term effects of surgery on progression of their AMD. Although traditional cataract surgery remains the mainstay of treatment, recently several devices have been developed to address the specific needs of AMD patients with cataract. We look at the associations between cataract and AMD and outline the treatment approaches to cataract surgery in AMD, looking at the potential benefits and risks of both traditional approaches and newer devices. We provide clinicians treating patients with AMD and cataract with a framework for choosing the appropriate management.

Effect of yellow-tinted intraocular lens on standard automated perimetry and short wavelength automated perimetry in patients with glaucoma

Purpose:

To investigate the effect of cataract surgery and yellow-tinted intraocular lens (IOLs) implantation on perimetry indices of short-wavelength automated perimetry (SWAP) and standard automated perimetry (SAP) testing in patients with coexisting cataract and glaucoma.

Materials and Methods:

In this prospective comparative case series, phacoemulsification with implantation of yellow-tinted Acrysof Natural IOL was performed in 16 eyes of 16 patients with visually significant cataract (best-corrected visual acuity (VA) better than 20/120) and mild to moderate glaucoma. Pre- and postoperative values for VA and for perimetry indices including mean deviation (MD), pattern standard deviation (PSD), and foveal threshold (FT) from both SAP and SWAP testing were compared.

Results:

Postoperative VA improved significantly after cataract surgery and yellow-tinted IOL implantation (P < 0.001). After cataract extraction and IOL implantation, MD and FT on SWAP testing improved significantly (P = 0.001); however, there was no statistically significant change with SAP testing between the pre- and postoperative perimetry indices. There was no statistically significant change in PSD with either SAP or SWAP testing postoperatively. The differences between pre- and postoperative values for all perimetry indices under study were not significant when comparing SAP with SWAP tests, except for MD which had improved statistically significantly in SWAP testing (P = 0.03).

Conclusions:

In mild to moderate glaucoma patients with cataracts, the perimetry indices of SWAP testing improved after phacoemulsification and yellow-tinted IOL implantation. This suggests that the yellow-tinted IOLs have less effect on SWAP testing than visually significant cataracts.

Patient-Reported Difference following Implantation of a Blue Light-Filtering Aspheric Intraocular Lens and a UV-Filtering Aspheric Intraocular Lens

We report on a series of 6 patients who experienced yellow vision after uncomplicated cataract surgery in their second eye. In the first eye, an aspheric blue-light filtering intraocular lens (IOL) was implanted, followed by the implantation of a 1-Piece aspheric IOL in the second eye. The time between the surgeries ranged from 12 months to 3 years. The patients experienced noticeable differences between the yellow and the clear lens. It is suggested to avoid mixing blue light-filtering and UV-filtering IOLs in the same patient, particularly in those who have high expectations following cataract surgery.

Premium IOLs in Glaucoma

Advanced technology or premium intraocular lenses have been developed to meet the patient expectations of perfect distance and near vision without the need for spectacles. Careful patient selection is critical when implanting these implants. This brief review focusses mainly on multifocal and toric IOLs and their application and limitations in patients with glaucoma.

How to cite this article: Ichhpujani P, Bhartiya S, Sharma A. Premium IOLs in Glaucoma. J Current Glau Prac 2013;7(2): 54-57.

Comparison of blue light-filtering IOLs and UV light-filtering IOLs for cataract surgery: a meta-analysis

BACKGROUND

A number of published randomized controlled trials have been conducted to evaluate visual performance of blue light-filtering intraocular lenses (IOL) and UV light-filtering intraocular lenses (IOL) after cataract phacoemulsification surgery. However, results have not always been consistent. Therefore, we carried out a meta-analysis to compare the effectiveness of blue light-filtering IOLs versus UV light-filtering IOLs in cataract surgery.

METHODS AND FINDINGS

Comprehensive searches of PubMed, Embase, Cochrane Library and the Chinese BioMedical literature databases were performed using web-based search engines. Fifteen trials (1690 eyes) were included for systematic review, and 11 of 15 studies were included in this meta-analysis. The results showed that there were no significant differences in postoperative mean best corrected visual acuity, contrast sensitivity, overall color vision, or in the blue light spectrum under photopic light conditions between blue light-filtering IOLs and UV light-filtering IOLs [WMD = -0.01, 95%CI (-0.03, 0.01), P = 0.46; WMD = 0.07, 95%CI (-0.04, 0.19), P = 0.20; SMD = 0.14, 95%CI (-0.33, 0.60), P = 0.566; SMD = 0.20, 95%CI (-0.04, 0.43), P = 0.099]. However, color vision with blue light-filtering IOLs was significantly reduced in the blue light spectrum under mesopic light conditions [SMD = 0.74, 95%CI (0.29, 1.18), P = 0.001].

CONCLUSION

This meta-analysis demonstrates that postoperative visual performance with blue light-filtering IOLs is approximately equal to that of UV light-filtering IOLs after cataract surgery, but color vision with blue light-filtering IOLs demonstrated some compromise in the blue light spectrum under mesopic light conditions.

Does the eye benefit from wearing ultraviolet-blocking contact lenses?

OBJECTIVES

The human eye is exposed to toxic ultraviolet radiation (UVR) from sunlight and artificial sources. The UVR-induced damage occurs in ocular tissues from the corneal surface to the retina. Although the cornea and crystalline lens provide inherent UVR protection, the anterior ocular surface and the limbus, which contains stem cells, receive toxic levels of UVR from relatively short solar exposures.

METHODS

Shading headwear and some UVR-blocking sunglasses are designed to reduce direct solar exposure but may not protect the eye from diffuse ambient and surface reflected light. If the squint mechanism is reduced because of the reduction of visible light, the ocular surface is then exposed to ambient and reflected UVR. In addition, laterally incident radiation that is focused across the cornea onto the limbus, a phenomenon known as peripheral light focusing, can increase the dose at the nasal limbus by a factor of 20.

RESULTS

The UVR-blocking contact lenses that cover the limbus provide protection from all sources of ocularly incident UVR. Although directly relating solar UVR dose to ocular damage is epidemiologically challenging, irradiation of ocular cell cultures can estimate the toxic effects of UVR exposure. The use of UVR-blocking contact lenses greatly increases the time the wearer can be exposed to solar UVR before a toxic ocular dose is reached.

CONCLUSIONS

There is a need for the development of a scientifically rigorous, clinically applicable ocular protection factor metric, based not only on the transmittance of eyewear but on the protection afforded from the total UVR field and the length of that exposure.

Effect of blue-light filtering on multifocal visual-evoked potentials

PURPOSE

To perform an objective functional assessment of the impact of blue-light filters on cortical processing to evaluate the potential side effects of the filters on higher tier visual function at the neural level.

SETTING

Department of Ophthalmology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany.

DESIGN

Cohort study.

METHODS

Multifocal pattern-reversal visual-evoked potentials (multifocal VEPs) were recorded monocularly in pseudophakic patients with a clear intraocular lens (IOL) under 2 conditions: (1) stimulus perception through a yellow filter with the filter characteristics of an AF-1 YA-60BB IOL (blue filtering); (2) stimulus perception through a neutral filter that homogeneously attenuates the effective stimulus intensity as under the blue-light filtering condition but independent of the wavelength (neutral filtering). Second-order kernel multifocal VEPs were extracted for 60 visual field locations, and amplitude and latency effects were determined for 6 stimulus eccentricities.

RESULTS

The study evaluated 20 patients. Typical multifocal VEPs were obtained for the blue-light and neutral filtering conditions at all eccentricities. No significant effects on amplitudes were obtained, and a subtle latency effect (<0.5 millisecond delay for neutral filtering; P<.02) did not reach significance in an eccentricity-specific analysis.

CONCLUSIONS

The induced short-term change in the spectral composition of the visual stimulus left neural activity at the level of the primary visual cortex largely unaffected, providing an objective account of the integrity of visual processing under this condition.

Recent studies provide an updated clinical perspective on blue light-filtering IOLs

Background

Recent reviews of blue light-filtering intraocular lenses (IOLs) have stated their potential risks for scotopic vision and circadian photoentrainment. Some authors have challenged the rationale for retinal photoprotection that these IOLs might provide. Our objective is to address these issues by providing an updated clinical perspective based on the results of the most recent studies.

Methods

This article evaluates the currently available published papers assessing the potential risks and benefits of blue light-filtering IOLs. It summarizes the results of seven clinical and two computational studies on photoreception, and several studies related to retinal photoprotection, all of which were not available in the previous reviews. These results provide a clinical risk/benefit analysis for an updated review for these IOLs.

Results

Most clinical studies comparing IOLs with and without the blue light-filtering feature have found no difference in clinical performance for; visual acuity, contrast sensitivity, color vision, or glare. For blue light-filtering IOLs, three comparative clinical studies have shown improved contrast sensitivity and glare reduction; but one study, while it showed satisfactory overall color perception, demonstrated some compromise in mesopic comparative blue color discrimination. Comparative results of two recent clinical studies have also shown improved performance for simulated driving under glare conditions and reduced glare disability, better heterochromatic contrast threshold, and faster recovery from photostress for blue light-filtering IOLs. Two computational and five clinical studies found no difference in performance between IOLs with or without blue light-filtration for scotopic vision performance and photo entrainment of the circadian rhythm. The rationale for protection of the pseudophakic retina against phototoxicity is discussed with supporting results of the most recent computational, in-vitro, animal, clinical, and epidemiological investigations.

Conclusions

This analysis provides an updated clinical perspective which suggests the selection of blue light-filtering IOLs for patients of any age, but especially for pediatric and presbyopic lens exchange patients with a longer pseudophakic life. Without clinically substantiated potential risks, these patients should experience the benefit of overall better quality of vision, reduced glare disability at least in some conditions, and better protection against retinal phototoxicity and its associated potential risk for AMD.

Electronic supplementary material

The online version of this article (doi:10.1007/s00417-011-1697-6) contains supplementary material, which is available to authorized users.

Comparison of photochromic, yellow, and clear intraocular lenses in human eyes under photopic and mesopic lighting conditions

PURPOSE

To evaluate the results of the first blue light-filtering photochromic intraocular lens (IOL) and compare them with those of a regular yellow blue light-filtering IOL and a clear ultraviolet-filtering IOL in human eyes under various lighting conditions.

SETTING

Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, China.

DESIGN

Prospective comparative clinical study.

METHODS

This study evaluated eyes that had implantation of 1 of the following 3 IOLs: photochromic Aurium Matrix acrylic, model 400; yellow AF-1 (UY); or clear MC611MI. All eyes were followed for 3 months. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, contrast vision (lighting 400 lux, 30 lux, 5 lux), contrast sensitivity, color vision (Farnsworth-Munsell 100-hue test under 400 lux, 30 lux), and patient questionnaire responses were evaluated.

RESULTS

The photochromic IOL group comprised 39 eyes; the yellow IOL group, 41 eyes; and the clear IOL group, 38 eyes. There were no significant differences between the 3 IOLs in UDVA, CDVA, contrast sensitivity, or questionnaire responses. The photochromic group had significantly better color vision than the yellow IOL group at 30 lux and better contrast vision at 5% contrast (P < .05); however, there were no significant differences between the photochromic IOL group and the clear IOL group (P > .05).

CONCLUSION

The photochromic blue light-filtering IOL performed as well as the yellow and clear IOLs under photopic conditions. Under mesopic conditions, the yellow IOL gave poor color vision and contrast sensitivity.

Comparison of visual performance with blue light-filtering and ultraviolet light-filtering intraocular lenses

PURPOSE

To compare the contrast sensitivity, glare, color perception, and visual acuity at different light intensities with yellow-tinted and clear intraocular lenses (IOLs) by different manufacturers.

SETTING

Ludwig Boltzmann Institute of Retinology and Biomicroscopic Laser-Surgery, Department of Ophthalmology, Rudolf Foundation Clinic, Vienna, Austria.

DESIGN

Comparative case series.

METHODS

Eyes were randomized to 1 of the following IOLs: AF-1 (UY) (yellow tinted), AcrySof SN60AT (yellow tinted), AF-1 (UV) (clear), or AcrySof SA60AT (clear). One week and 2 months postoperatively, monocular contrast sensitivity function and color discrimination were tested and the corrected distance and near visual acuities were evaluated. All tests were performed under different light intensities (10 to 1000 lux).

RESULTS

Of the 80 patients enrolled, 76 completed the study; there were 37 eyes in the yellow-tinted IOL group and 39 in the clear IOL group. There were no significant differences between yellow-tinted IOLs and clear IOLs except in color vision under mesopic conditions (10 lux). Patients with a yellow-tinted IOL made significantly more mistakes in the blue-light spectrum than patients with clear IOLs (P = .00015). There was no significant difference under photopic conditions (1000 lux).

CONCLUSIONS

The yellow-tinted IOLs were equivalent to the clear IOLs in postoperative contrast sensitivity, visual acuity, and color perception under photopic conditions. Patients with yellow-tinted IOLs made statistically significantly more mistakes in the blue range under dim light than patients with clear IOLs.

Spectral transmittance of intraocular lenses under natural and artificial illumination: criteria analysis for choosing a suitable filter

PURPOSE

To compare the spectral transmission of different intraocular lenses (IOLs) with either ultraviolet (UV) or blue-light filters, and to analyze the performance of these filters with artificial light sources as well as sunlight.

DESIGN

Experimental study.

METHODS

The spectral transmission curve of 10 IOLs was measured using a PerkinElmer Lambda 800 UV/VIS spectrometer (Waltham, MA). Different filtering simulations were performed using the D65 standard illuminant as daylight and standard incandescent lamp and fluorescent bulb illuminants.

MAIN OUTCOMES MEASURES

Spectral transmittance of the IOLs.

RESULTS

All the IOLs studied provide good UVC (200-280 nm) and UVB (280-315 nm) protection, except for one that presented an appreciable window at 270 nm. Nevertheless, both natural and artificial sources have practically no emission under 300 nm. In the UVA (315-380 nm) range the curves of the different IOLs manifested different degrees of absorption.

CONCLUSIONS

Not all the UV filters incorporated in different IOLs protect equally. The filters that provide greater photoprotection against UV radiation, even blue light, are yellow and orange. Then, yellow and orange IOL filters may be best suited for cases requiring special retinal protection. The filters that favor better photoreception of visible light (380-780 nm) are those that transmit this radiation close to 100%. Artificial illumination practically does not emit in the UV range, but its levels of illumination are very low when compared with solar light. A possible balance between photoprotection and photoreception could be a sharp cutoff filter with the cutoff wavelength near 400 nm and a maximum transmittance around 100%.

Blue-blocking IOLs: a complete review of the literature

Intraocular lenses (IOLs) that block both ultraviolet and blue wavelength light (<500 nm)were introduced in the 1990s. Since then, the potential benefits and harm from blocking blue light has been debated. We report the results of a complete review of all peer-reviewed published studies regarding the impact of blocking the transmission of blue light. Fifty-six published reports on subjects related to blue-blocking lenses including sleep disturbance, visual outcomes, cataract surgery, lens transmittance, sunlight exposure, and macular disease were found in peer reviewed journals from 1962 to 2009. Eleven reports specifically compared visual outcomes between blue-blocking IOLs and nonblue-locking IOLs. Of these, 10 independent studies (10/11, 91%) concluded that there are no significant effects of blue-blocking IOLs on various meters of visual performance including visual acuity, contrast sensitivity, color perception, and photopic, mesopic, and scotopic sensitivities. Only one group of authors reported that the use of blue-blocking IOLs may have detrimental effects on scotopic vision and circadian rhythms. However, the actual clinical significance of these potential negative effects on scotopic vision and on sleep patterns is uncertain. The benefits of blocking the transmission of blue light to the macula and the relationship between progression of age-related macular degeneration remain unclear. However, the published studies clearly state that the use of blue-blocking IOLs is not detrimental in visual acuity, color perception, and contrast sensitivity. The reported potential negative effects on scotopic vision and sleep disturbance appear to be minimal and may not be clinically relevant. (Surv Ophthalmol 55:284--289, 2010. 2010 Elsevier Inc. All rights reserved.)

Color discrimination by patients with different types of light-filtering intraocular lenses

PURPOSE

To evaluate photopic and mesopic color discrimination in patients with different types of light-filtering intraocular lenses (IOLs).

SETTING

Peking University Third Hospital, Peking University Eye Center, Beijing, China.

METHODS

Cataract patients with different types of IOLs were enrolled 3 months postoperatively. Overall and partial color discrimination under photopic (1000 lux) and mesopic (40 lux) conditions were evaluated with the Farnsworth-Munsell (FM) 100-hue test. Corrected distance visual acuity (CDVA) was tested under both conditions. Subjective visual quality was assessed with the 25-item National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25).

RESULTS

The study evaluated 43 patients with a blue light-filtering IOL (15 photochromic, 13 yellow tinted) or an IOL filtering ultraviolet light only (n = 15). The difference in the FM 100-hue total error scores under photopic or mesopic conditions was not statistically significant between groups. There were no statistically significant differences in partial error scores in the 10 bands of the FM 100-hue color circle under photopic conditions. Under mesopic condition, there were statistically significant differences in partial error scores in the green to blue-green band (color caps 36 to 46) and the blue-green to blue band (color caps 46 to 54) (P = .005 and P = .030, respectively). There were no statistically significant differences in mean overall or subheading NEI VFQ-25 scores.

CONCLUSIONS

Filtering blue lights under mesopic conditions seemed to modify color discrimination in the green-to-blue bands postoperatively. The modification did not disturb overall color discrimination or cause subjective discomfort.

Blue-blocking IOLs decrease photoreception without providing significant photoprotection

Violet and blue light are responsible for 45% of scotopic, 67% of melanopsin, 83% of human circadian (melatonin suppression) and 94% of S-cone photoreception in pseudophakic eyes (isoilluminance source). Yellow chromophores in blue-blocking intraocular lenses (IOLs) eliminate between 43 and 57% of violet and blue light between 400 and 500 nm, depending on their dioptric power. This restriction adversely affects pseudophakic photopic luminance contrast, photopic S-cone foveal threshold, mesopic contrast acuity, scotopic short-wavelength sensitivity and circadian photoreception. Yellow IOL chromophores provide no tangible clinical benefits in exchange for the photoreception losses they cause. They fail to decrease disability glare or improve contrast sensitivity. Most epidemiological evidence shows that environmental light exposure and cataract surgery are not significant risk factors for the progression of age-related macular degeneration (AMD). Thus, the use of blue-blocking IOLs is not evidence-based medicine. Most AMD occurs in phakic adults over 60 years of age, despite crystalline lens photoprotection far greater than that of blue-blocking IOLs. Therefore, if light does play some role in the pathogenesis of AMD, then 1) senescent crystalline lenses do not prevent it, so neither can blue-blocking IOLs that offer far less photoprotection, and 2) all pseudophakes should wear sunglasses in bright environments. Pseudophakes have the freedom to remove their sunglasses for optimal photoreception whenever they choose to do so, provided that they are not encumbered permanently by yellow IOL chromophores. In essence, yellow chromophores are placebos for prevention of AMD that permanently restrict a pseudophake's dim light and circadian photoreception at ages when they are needed most. If yellow IOLs had been the standard of care, then colorless UV-blocking IOLs could be advocated now as "premium" IOLs because they offer dim light and circadian photoreception roughly 15-20 years more youthful than blue-blocking IOLs.