Color perception with AcrySof Natural and AcrySof single-piece intraocular lenses under photopic and mesopic conditions

Blue Light Filtration in Intraocular Lenses: Effects on Visual Function and Systemic Health

Blue light-filtering (BLF) intraocular lenses (IOLs) are designed to mimic the healthy natural adult crystalline lens. Studies that evaluated the relative merit of ultraviolet-only IOL design (ie, blocking wavelengths <400 nm) versus BLF IOL design (ie, filtering wavelengths ~400-475 nm in addition to blocking wavelengths <400 nm) on protection and function of the visual system suggest that neither design had a deleterious impact on visual acuity or contrast sensitivity. A BLF design may reduce some aspects of glare, such as veiling and photostress. BLF has been shown in many contexts to improve visual performance under conditions that are stressed by blue light, such as distance vision impaired by short-wave dominant haze. Furthermore, some data (mostly inferential) support the notion that BLF IOLs reduce actinic stress. Biomimetic BLF IOLs represent a conservative approach to IOL design that provides no harm for visual acuity, contrast sensitivity, or color vision while improving vision under certain circumstances (eg, glare).

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.

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.

Influence of Intraocular Lens Asphericity and Blue Light Filtering on Visual Outcome, Contrast Sensitivity, and Aberrometry after Uneventful Cataract Extraction

Purpose

To evaluate the effect of asphericity and blue light filter (BLF) of three different intraocular lenses (IOLs) on the visual performance, second- and third-order aberrations (defocus, coma, trefoil), and contrast sensitivity after uneventful cataract surgery.

Methods

One hundred and twenty eyes of 60 patients with clinically significant cataract were randomly assigned to receive one of the three IOL types: Bioline Yellow Accurate (aspheric, with BLF, i-medical, Germany), BioAcryl 60125 (spherical, without BLF, Biotech, France), and H65C/N (aspheric, without BLF, PhysIOL, Belgium). Each IOL was implanted in 40 eyes. Complete ophthalmologic examination, functional acuity contrast testing and wavefront analysis were performed 60 days postoperatively.

Results

The mean postoperative best-corrected visual acuity (BCVA) was 0.95 ± 0.08, not differing statistically among the IOL groups (P = 0.83). Mean defocus and coma values did not yield any statistically significant difference through the IOL groups varying from –0.784 to –0.614 μm and 0.129 to 0.198 μm (P = 0.79 and 0.34, respectively). Bioline Yellow Accurate IOL presented less trefoil aberrations, 0.108 ± 0.05 μm, compared to the other two IOL types (BioAcryl [0.206 ± 0.19 μm] and Physiol [0.193 ± 0.17 μm], P< 0.05). Contrast sensitivity values did not differ among the groups under all lighting conditions. Bioline Yellow IOL showed a statistically higher loss of contrast sensitivity (between mesopic and mesopic with glare conditions) compared to the BioAcryl and PhysIOL in 12 and 3 cpd spatial frequencies, respectively (P< 0.05).

Conclusion

Bioline Yellow IOL indicated lower contrast sensitivity under mesopic conditions when glare was applied but resulted in less trefoil aberrations after uneventful cataract surgery. No further differences were noted in postoperative visual performance among three IOL groups.

The Effects of Blue Light-Filtering Intraocular Lenses on the Protection and Function of the Visual System

Filtration of high-energy short-wave visible light (blue light) to improve vision and protect against damage has evolved both in aquatic animals and terrestrial species. In humans, pigments in the inner layer of the macula absorb wavelengths between 400 and 520 nm and function to improve visual performance. In patients who undergo cataract surgery, replacing cataractous lenses with artificial intraocular lenses (IOLs) that do not mimic normal healthy adult lenses could result in preventable negative visual effects, including glare disability. Blue light-filtering (BLF) IOLs were designed to filter short-wave light in addition to ultraviolet light and mimic the natural crystalline lens. Current studies indicate that BLF IOLs may provide protection from blue light-induced retinal damage and slow the development and progression of age-related macular degeneration. Additionally, BLF IOLs have been shown to improve chromatic contrast, reduce photostress recovery time, reduce glare disability and discomfort, and generally improve visual performance under glare conditions. Although a number of concerns have been raised about the relative risks versus the benefits of BLF IOLs, recent studies reported no adverse effects on visual function or contrast under photopic conditions, no long-term effects on color vision, and no detrimental effects on circadian rhythms with BLF IOLs. Based on the current understanding of the field, evidence suggests that BLF IOLs would be returning the eye to a more natural state compared with non-BLF lenses.

Evaluation of Visual Quality in Pseudophakic Eyes with Different Ocular Spherical Aberrations

Purpose: To evaluate the effects of different residual total ocular spherical aberration (SA) on objective and subjective visual quality in pseudophakic eyes. Methods: This prospective consecutive study comprised 171 patients with age-related cataract and undergone unilateral uneventful phacoemulsification. All participants were divided into four groups based on residual ocular SA at 6 mm pupil: negative SA (≤-0.10 μm, group A), neutral SA (0.00 ± 0.05 μm, group B), slightly positive SA (0.10 ± 0.05 μm, group C), and more positive SA (0.20 μm, group D), respectively. Subjective visual acuity and contrast sensitivity, and objective optical quality and ocular aberrations were analyzed 3 months postoperatively. Results: There was no significant difference in baseline measurements across all groups. Postoperatively, no statistically significant differences were found in visual acuity between groups (P > .05), while differences reached statistical significance in mesopic contrast sensitivity at 12 and 18 cpd (P < .01). There were significant differences in ocular SA and higher-order aberrations at 6 mm pupil, as well as in optical quality parameters (P < .05). Group C showed a minimum value of objective scatter index (1.17 ± 0.55) but maximum values of modulation transfer function cutoff (31.94 ± 9.18) and optical quality value OV 100% (1.07 ± 0.31), indicating lower intraocular scattering and superior optical quality. Conclusions: This comprehensive evaluation is conducive to deepening the understanding of visual and optical performance of pseudophakic eye. A modest amount of positive ocular SA seemed to be a more preferable option for enhancing visual quality after aspheric ntraocular lense (IOL) implantation.

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.

Intraindividual Comparison of Color Perception and Contrast Sensitivity with and without a Blue Light-Filtering Intraocular Lens

Purpose

To investigate color perception and contrast sensitivity with and without additional glare in pseudophakic patients with a conventional intraocular lens (IOL) in one eye and a blue light-filtering IOL in the fellow eye.

Methods

Twenty-three bilaterally pseudophakic patients with a conventional IOL (Acr ySof SA60AT) and a blue light-filtering IOL (AcrySof Natural SN60AT) were tested for intraindividual comparison of visual acuity (ETDRS chart), color perception (Farnsworth-Munsell 100-Hue test), and contrast sensitivity with and without glare (Contrast Sensitivity Pattern Generator). Information about subjective perception was gathered through a questionnaire.

Results

Four patients (17.4%) observed some difference in monocular color perception. Color testing did not show significantly different results for the two IOL types expressed as total error score and segmental error subscores for protan, deutan, and tritan ranges. Regarding contrast sensitivity, 5 patients (21.7%) indicated noticeable difference between the two eyes. Contrast sensitivity testing, however, showed similar curves for the two IOL types with and without additional glare.

Conclusions

Despite some subjective difference in color and contrast perception in a minority of patients, the study did not show significantly different results for the two IOL types.

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.

Effect of blue light-filtering intraocular lens on color vision in patients with macular diseases after vitrectomy

To evaluate the color vision of patients with macular diseases after implanting a blue light-filtering intraocular lens (IOL) during vitrectomy. Twenty-seven patients had a blue light-filtering IOL implanted during vitrectomy for macular diseases (macular disease group), and 40 patients without macular disease had the same type of IOL implanted (non-macular disease group). The postoperative best-corrected visual acuity (BCVA) was ≥ 16/20 in all patients. The Farnsworth-Munsell 100-hue test was used to determine total error scores (TES) and mean error scores under photopic and mesopic conditions in both groups. The TES under mesopic conditions was significantly higher than that under photopic conditions in both groups (P < 0.05). However, the TES in the macular disease group was not significantly different from that of the non-macular disease group under both photopic and mesopic conditions. The mean error scores under photopic conditions for hues 11, 14, 16, 17, 18, and 20 (yellowish-red to yellow) were significantly higher in the macular disease group than in the non-macular disease group. The mean error scores for hues 7 and 85 (red) were significantly higher in the non-macular disease group than in the macular disease group. Under mesopic conditions, the mean error scores for hues 30, 60, and 61 were significantly higher in the non-macular disease group than in the macular disease group (P < 0.05). Our results indicate that blue light-filtering IOLs do not alter color discrimination in eyes with macular diseases, and these patients had good postoperative BCVA even under mesopic conditions.

Effect of the color of the intraocular lens on optical and visual quality

Purpose: To analyze the optical quality of intraocular lenses (IOL) with an orange (PC440Y) and a yellow (SN60AT) filter, and correlate these results with the visual quality of patients with these implants. Setting: Fisabio Oftalmologνa Mιdica, Valencia, Spain. Design: Randomized prospective study. Materials and Methods: The IOL optical quality was determined using the modulation transfer function (MTF) and the spectral transmission. The visual quality of 87 eyes with cataract (51 with orange filter and 36 with yellow filter) was determined by best corrected visual acuity (BCVA) and contrast sensitivity function (CSF) under photopic and mesopic conditions. To analyze the results, we use a Student's t-test. Results: Orange lens filtered more of the blue spectrum (cut-off wavelength of 370 nm) than the yellow lens (390 nm). The MTF of the yellow lens was better than the orange lens (average modulation of 0.676 for natural and 0.672 for orange). The patients' BCVA was 0.02 + 0.10 logMAR for both lenses. The CSF obtained with the yellow lens was slightly better, although without statistically significant differences (P > 0.05). Conclusions: Both lenses are of good optical quality. The patients' visual quality was similar with both lenses, and optical quality was also similar. The color of the lens does not affect the visual quality of the patient.

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.

Blue-light-blocking intraocular lens implantation improves the sleep quality of cataract patients

STUDY OBJECTIVES

To evaluate whether blue-light-blocking intraocular lens implantation affects the sleep quality of cataract patients.

DESIGN

Pre-test/post-test experiment.

SETTING

N/A.

PARTICIPANTS

40 patients having bilateral cataracts with level higher than N3 (LOCS II) nucleus hardness, including 26 females (65%) and 14 males (35%).

INTERVENTIONS

Cataract phacoemulsification followed by blue-light-blocking intraocular lens (IOLs, SN60WF, Alcon Laboratories, USA) implantation.

MEASUREMENTS AND RESULTS

Patients were contacted in site before cataract surgery and followed by telephone at least 2 months later after second-eye surgery. Pittsburgh Sleep Quality Index (PSQI) questionnaires were administered to evaluate sleep quality. Median age of patients was 74 years (IQR 70 to 78). The median PSQI globe scores were 7 before surgery and 4 after surgery (Z = -2.121, p = 0.037). More specifically, there were significant differences on subjective sleep quality (Z = -2.064, p = 0.045), sleep duration (Z = -2.037, p = 0.047) and daytime dysfunction (Z = -2.142, p = 0.034) when compared between before and after surgeries. The ratio of poor sleepers (PSQI > 5) was reduced significantly after surgery (χ² = 14.532, p < 0.001).

CONCLUSIONS

Blue-light-blocking IOL had a significantly beneficial effect on the sleep quality of cataract patients.

Contrast sensitivity and color perception with orange and yellow intraocular lenses

PURPOSE

To evaluate contrast sensitivity function (CSF) and color vision after implantation of either orange or yellow-tinted intraocular lenses (IOLs).

METHODS

Fifty-six eyes of 28 cataract patients who had bilateral implantation of orange-tinted (PC440Y Orange, Ophtec), yellow-tinted (AcrySof Natural SN60AT, Alcon), or clear (AcrySof SA60AT, Alcon) IOLs were examined. Six months postoperatively, monocular CSF under photopic and mesopic (with and without glare) conditions were measured using the Functional Visual Analyzer. Color discrimination was determined with the Farnsworth-Munsell 100-Hue test.

RESULTS

Patients implanted with orange-tinted, yellow-tinted, or clear IOLs displayed similar CSF values, with no statistically significant differences at any spatial frequency (p>0.05). There were no statistically significant differences in chromatic discrimination among the 3 groups of patients (p>0.05).

CONCLUSIONS

Orange or yellow blue-filtering IOL implantation is comparable to a clear IOL in terms of photopic and mesopic contrast sensitivity or color discrimination.

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.

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.

Intraocular lens short wavelength light filtering

There is increasing interest in the effects of reactive oxygen species ('free radicals') in ageing, both in the body overall and specifically in the eye. Cataract and age-related macular degeneration (AMD) are two major causes of blindness, with cataract accounting for 48 per cent of world blindness and AMD accounting for 8.7 per cent. Both cataract and AMD affect an older population (over 50 years of age) and while cataract is largely treatable provided resources are available, AMD is a common cause of untreatable, progressive visual loss. There is evidence that AMD is linked to exposure to short wavelength electromagnetic radiation, which includes ultraviolet, blue and violet wavelengths. The ageing crystalline lens provides some protection to the posterior pole because, as it yellows with age, its spectral absorption increasingly blocks the shorter wavelengths of light. Ultraviolet blocking intraocular lenses (IOLs) have been the standard of care for many years but a more recent trend is to include blue-blocking filters based on theoretical benefits. As these filters absorb part of the visible spectrum, they may affect visual function. This review looks at the risks and the benefits of filtering out short wavelength light in pseudophakic patients.

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.

The Effect of the AcrySof natural lens on glare disability and photostress

PURPOSE

To investigate whether implanting "blue-filtering" yellow intraocular lenses (IOL) could provide a visual benefit in terms of glare disability and photostress recovery.

DESIGN

A case-control study.

METHODS

Researchers masked to group assignments tested 58 subjects: 17 with yellow IOLs (AcrySof Natural; SN60WF; Alcon Laboratories Inc, Fort Worth, Texas, USA), 20 with clear IOLs, and 21 phakic controls. Photostress recovery and visual acuity under veiling glare conditions were assessed in a Maxwellian view optical system. Photostress recovery was assessed by measuring the time required to detect a grating stimulus (1 degree diameter) after a 5-second exposure to an intense circular disk (1 degree diameter) of broad-band xenon light. For the veiling glare experiment, subjects fixated on the grating stimulus, and the intensity of a broad-band xenon annulus (the glare source, 10 degrees inner, 12 degrees outer diameter) was adjusted until the grating stimulus was no longer seen.

RESULTS

Subjects with AcrySof Natural (P < .0001) and clear IOLs (P < .035) could withstand significantly more light than the phakic controls. Subjects with the AcrySof Natural lens could withstand significantly more light (P < .02) than subjects with clear IOLs. Photostress recovery was significantly longer for subjects with clear IOLs vs phakic controls (P < .01), but the AcrySof Natural lens was not different from phakic controls (P < .09). Photostress recovery was similar between subjects with clear or AcrySof Natural lens (P < .32).

CONCLUSION

The AcrySof Natural lens is related to reduced glare disability relative to a clear IOL or phakic controls.

Evaluation of early state of cyanopsia with subjective color settings immediately after cataract removal surgery

We evaluated cyanopsia by means of achromatic-point settings at several time points started from the day before intraocular lens (IOL) implantation for cataract removal surgery. We intensively measured the initial drift in color appearance; we started the measurement less than 30 min after eyepatch removal, and the measurement continued for several weeks. The shifts were mainly observed in the direction of color space that selectively varies short-wavelength-sensitive cone (S-cone) responses. The time constant of shifts in color appearance was estimated at the initial stage of cyanopsia by fitting exponential curves. The result of fitting suggests that color appearance is recalibrated during cyanopsia by some neural mechanisms with a time constant of several hours. It also became clear that the migration of the achromatic point becomes slower within approximately 12 h after eyepatch removal.

Effect of a blue-light-blocking intraocular lens on the quality of sleep

PURPOSE

To evaluate whether implantation of a blue-light-blocking intraocular lens (IOL) affects sleep quality.

SETTING

Repatriation General Hospital, Adelaide, Australia.

METHODS

This study comprised patients who had bilateral cataract surgery during the preceding 12 months with implantation of a conventional SI40NB IOL or an AcrySof Natural SN60WF blue-light-blocking IOL. Patients were contacted by telephone at least 6 months after second-eye surgery, and the Pittsburgh Sleep Quality Index (PSQI) questionnaire was administered. Results were compared between groups.

RESULTS

Of the 49 patients, 31 received conventional IOLs and 18, blue-light-blocking IOLs. The mean age of the patients was 80 years +/- 8.1 (SD). The median PSQI score was 6 (interquartile range 3 to 8). There were no statistically significant differences in PSQI scores between the 2 IOL groups (P = .65). This remained true after adjustment for sex, age, medication, and time since surgery.

CONCLUSION

The blue-light-blocking IOL had no effect on the sleep quality of patients, indicating that these IOLs might serve as an alternative to conventional IOLs without a detrimental effect on circadian rhythm.

Transmittance characteristics of ultraviolet and blue-light-filtering intraocular lenses

PURPOSE

To record the spectral transmittance curves of various ultraviolet (UV) and blue-light-filtering intraocular lenses (IOLs), evaluate their UV and blue-light-radiation- absorption capacities, and compare them with those of the natural crystalline lens.

SETTING

Department of Ophthalmology, Duisburg-Essen University, Essen, Germany.

METHODS

Eight IOLs from 6 manufacturers were evaluated. The transmittance of wavelengths from 200 nm to 800 nm was measured using a high-performance spectrophotometer with a diffuse transmittance accessory through a 1.5 mm aperture.

RESULTS

All assessed IOLs provided good UVC (200 to 280 nm) and UVB (280 to 320 nm) protection, but 2 IOLs lacked sufficient UVA (320 to 400 nm) protection. Major differences in the absorption capacities were observed in the blue-light range (400 to 500 nm).

CONCLUSIONS

The absorption characteristics of some UV and blue-light-filtering IOLs resembled those of the crystalline lens, but some differed. Long-term clinical trials should be performed to determine how blue-blocking IOLs affect the risk for progression of age-related macular degeneration.

Blue light-filter intraocular lenses in vitrectomy combined with cataract surgery: results of a randomized controlled clinical trial

PURPOSE

To evaluate the effect of the blue light-filter intraocular lenses (IOLs) in vitrectomy combined with cataract surgery, focusing on the surgeon's ability to perform specific vitreoretinal procedures and on the patients' outcome.

DESIGN

Randomized clinical trial.

METHODS

Sixty patients, recruited from our outpatient department, were assigned randomly to receive an ultraviolet-filter IOL (clear IOL group) or a blue light-filter IOL (yellow IOL group) combined with a vitreoretinal procedure. Main outcome measures were intraoperative conditions for the surgeon and the functional outcome. Second outcome measures were complication rates and vitreoretinal diagnoses.

RESULTS

The questionnaire responses showed that the blue light-filter IOLs did not represent an impediment to vitreoretinal surgery (P>.05). No intraoperative complications were encountered in either group. Patients in both IOL groups showed comparable functional results with respect to visual acuity, contrast sensitivity, color vision, and glare effect (P>.05). The functional outcome was influenced significantly by the vitreoretinal diagnosis (P<.01).

CONCLUSIONS

With the possible advantage of macular protection and no intraoperative or functional disadvantage, the routine use of the blue light-filter IOL in combined surgery can be recommended.

Prospective Randomized Study of Clinical Performance of 3 Aspheric and 2 Spherical Intraocular Lenses in 250 Eyes

PURPOSE

To compare the quality of vision with aspheric and spherical intraocular lenses (IOLs) in pseudophakic patients.

METHODS

This prospective, comparative, randomized study included 250 eyes of 125 patients with bilateral cataracts. Patients were randomly assigned to receive either IOLs with a spherical biconvex optic (Acrysof SN6OAT [Alcon] or Sensar AR40e [Advanced Medical Optics, AMO]) or IOLs with an aspheric optic (Acrysof IQ SN6OWF [Alcon], Tecnis Z9000 [AMO], or Sofport L161AO [Bausch & Lomb]). Ophthalmologic examination including best spectacle-corrected visual acuity, pupil size, ocular dominance investigation, contrast sensitivity under mesopic and photopic conditions, and wavefront analysis was performed 2 months postoperatively.

RESULTS

Aspheric IOLs showed better contrast sensitivity compared to spherical IOLs at spatial frequencies of 6, 12, and 18 cycles per degree (cpd) under photopic conditions and at all spatial frequencies under mesopic conditions. There was no significant difference among the three aspheric IOLs at all spatial frequencies under either photopic or mesopic conditions. Mean total spherical aberration was statistically lower in dominant eyes with aspheric IOLs (0.05 +/- 0.06, 0.11 +/- 0.1, and 0.19 +/- 0.08 pm for the Tecnis Z9000, Acrysof IQ SN6OWF, and Sofport L161AO, respectively) compared with eyes with spherical IOLs (0.62 +/- 0.24 and 0.46 +/- 0.19 microm for the Acrysof SN6OAT and Sensar AR40e, respectively) for a 5-mm pupil diameter.

CONCLUSIONS

The aspheric IOLs had less wavefront aberrations and performed better under both photopic and mesopic contrast sensitivity compared to the spherical IOLs. These findings confirm it is possible to improve the optical performance of IOLs by modifying the surfaces.

Luminance contrast with clear and yellow-tinted intraocular lenses

PURPOSE

To determine whether yellow-tinted intraocular lenses (IOLs) negatively affect luminance contrast in postoperative cataract patients.

SETTING

Department of Ophthalmology, Sir Mortimer B. Davis Jewish General Hospital, McGill University, Montreal, Quebec, Canada.

METHODS

Luminance contrast was measured using the minimum-motion technique. The stimulus consisted of blue and red sinusoidal gratings differing in luminance. Patients had implantation of a clear or yellow-tinted IOL and were tested monocularly 2 to 9 weeks after cataract surgery. No patient had concomitant ocular diseases or congenital color defects, assessed by their ophthalmologist, or flicker-sensitive epilepsy. All patients had a visual acuity of 20/40 or better a mean of 4 weeks+/-2 (SD) postoperatively.

RESULTS

Patients ranged in age from 55 to 89 years. An independent-samples Student t test showed that patients with a yellow-tinted IOL had significantly lower luminance contrast values than patients with a clear IOL (P<.05).

CONCLUSIONS

The results suggest that yellow-tinted IOLs affect the perception of luminance under photopic conditions. More blue light was required to make luminance judgments with a yellow-tinted IOL than with a clear IOL. Further study of the functional impact of luminance reduction by yellow-tinted IOLs is warranted.

Effect of a yellow intraocular lens on scotopic vision, glare disability, and blue color perception

PURPOSE

To compare the photopic and scotopic contrast sensitivity with and without glare as well as blue color perception between eyes with an AcrySof SN60AT Natural intraocular lens (IOL) (Alcon Laboratories Inc.) and eyes with a conventional AcrySof SA60AT IOL.

SETTING

Ankara University School of Medicine, Department of Ophthalmology, Ankara, Turkey.

METHODS

Right eyes of 38 patients with an AcrySof Natural IOL and right eyes of 38 age-matched patients with a conventional AcrySof SA60AT IOL were included in a study. Contrast sensitivity was measured with the Functional Acuity Contrast Test under photopic conditions. Scotopic contrast sensitivity in the presence or absence of glare was measured using the Mesotest II (Oculus GmbH). Blue-green color vision was evaluated with the Moreland equation of the HMC Anomaloskop MR (Oculus GmbH).

RESULTS

The mean age of patients was 66.6 years +/- 8.2 (SD) in the Natural IOL group and 66.4 +/- 8.0 years in the conventional IOL group. There was no statistically significant difference in photopic contrast sensitivity, scotopic contrast sensitivity with and without glare, or disability glare between the 2 groups (P>.05). Photopic and scotopic contrast sensitivity with and without glare significantly decreased with age in both groups (P<.01). There was no statistically significant difference in anomaloscope scores between the 2 groups (P>.05). The Moreland middle match point showed a significant shift toward blue with age in both groups (P<.01).

CONCLUSIONS

The AcrySof SN60AT Natural IOL provided contrast sensitivity under photopic and scotopic conditions (with and without glare) and blue color perception comparable that obtained with the AcrySof SA60AT IOL. Scotopic vision and blue color discrimination decreased with age with both IOLs.

Scotopic sensitivity and color vision with a blue-light-absorbing intraocular lens

PURPOSE

To investigate possible adverse effects of a yellow-tinted intraocular lens (IOL) on scotopic sensitivity and hue discrimination.

SETTING

Departments of Ophthalmology, Columbia University and New York University School of Medicine, New York, New York, USA.

METHODS

Nine patients with a yellow-tinted IOL in 1 eye and a colorless ultraviolet IOL in the fellow eye and 9 young phakic subjects with and without a yellow-tinted clip-on lens were tested. Hue discrimination was measured with the Farnsworth-Munsell (FM) 100-hue test. Dark-adapted thresholds to 440 nm, 500 nm, and 650 nm lights were measured at 23 locations using a modified Humphrey perimeter, and dark-adapted thresholds to white light were measured at 15 degrees temporal retina.

RESULTS

In the 9 patients, there were no significant differences in dark-adapted sensitivities to 440, 500, 650 nm, or white-light stimuli and no differences in FM 100-hue error scores between eyes with yellow-tinted IOLs and those with colorless IOLs. Similarly, in young phakic subjects, there were no significant differences in FM 100-hue error scores or dark-adapted sensitivity to the white light with and without the yellow-tinted clip-on lens. However, with the clip-on lens, mean sensitivities to the 440 nm, 500 nm, and 650 nm stimuli were significantly decreased by 2.7 to 2.8 dB, 0.7 to 1.0 dB, and 0 to 1.2 dB, respectively.

CONCLUSION

Results suggest that implantation of a yellow-tinted IOL has non-significant effect on scotopic sensitivity and hue discrimination.

Comparison of visual function following implantation of Acrysof Natural intraocular lenses with conventional intraocular lenses

BACKGROUND

Recently an intraocular lens (IOL) has been introduced which blocks blue light. As blocking blue light may be to the patient's detriment, this study was designed to evaluate visual function following implantation of a blue-blocking (Acrysof Natural) IOL.

METHODS

Patients were recruited for this non-randomized controlled interventional study, from those attending a private rural ophthalmology clinic for cataract surgery (n = 93). Only those who had previously had a conventional IOL implanted into one eye were offered an Acrysof Natural IOL for the second eye. Postoperatively patients underwent refracted Snellen visual acuity, contrast sensitivity using a CSV-1000E instrument and colour vision testing using a Farnsworth D-15 test, with a subset (n = 20) undergoing a Farnsworth-Munsell 100-Hue test. Results were then compared between eyes. Finally, a subset (n = 63) completed a survey designed to assess the subjective impact of the Acrysof Natural IOL.

RESULTS

There were no statistically significant differences between eyes implanted with conventional IOLs compared with Acrysof Natural IOLs for visual acuity (t = 0.57; P = 0.57), contrast sensitivity (t = 0.43; P = 0.67 for 3 cycles per degree [cpd], t = 0.56; P = 0.58 for 6 cpd, t = 0.09; P = 0.93 for 12 cpd and t = 0.16; P = 0.87 for 18 cpd) or colour vision with the Farnsworth D-15 (Chi(2) = 0.38; P = 0.55) or the Farnsworth-Munsell 100-Hue test t = 0.34; P = 0.74). Most subjects reported that they could not tell a difference between the two IOLs subjectively or that any difference experienced was not significant.

CONCLUSION

Our sample did not show any significant differences between eyes implanted with conventional IOLs and the Acrysof Natural IOL. We would suggest that the Acrysof Natural IOL may be used without any significant difference in visual function.