Effect of Blue Light Filtering Intraocular Lenses on Visual Perception

Use of the perceptual point-spread function to assess dysphotopsias

Nowadays many patients are choosing EDOF or multifocal lenses for replacement of natural lens in cataract surgery. This can result in issues such as presence of dysphotopsias, namely halo and glare. In this work, we propose a new perimetry method to describe dysphotopsias in far-field region in a presence of bright, point-like light source. We constructed a custom device and designed measurement procedure for quantitative measurement of dysphotopias in the center of visual field and used it to examine patients with mild cataracts or implanted IOLs. Our approach may help in establishing an objective method to study and compare dysphotopsias.

Analyzing the effect of blue-blocking lenses on color vision tests using the chromaticity coordinate method

Significance

Blue light with wavelengths of 380-445 nm can harm the retina, leading to the development of blue-blocking lenses (BBLs). Understanding whether BBLs affect color vision test outcomes and color discrimination ability is crucial for people in color-associated jobs.

Aim

This study aimed to evaluate the effect of BBLs on color vision tests and analyze color discrimination using mathematical models of color spaces.

Approach

Six pseudoisochromatic (PIC) tests and two Farnsworth-Munsell (FM) tests were conducted to assess participants' color vision. Friedman signed rank test was used to compare the outcomes of the Farnsworth-Munsell 100-Hue Tests (FM 100-Hue Tests) between the BBLs and ordinary lenses groups. The CIE color difference formula and a spectral illuminometer were employed to evaluate the color differences with and without BBLs.

Results

All subjects showed normal outcomes in all PIC tests and Farnsworth-Munsell Dichotomous D-15 Tests (FM D-15 Tests). There were no significant differences between ordinary lenses group and BBLs groups in FM 100-Hue Tests. In the color space, the effect of BBLs on each color light was equivalent to a translation on the CIE 1931 chromaticity diagram with minor distortion. Since BBLs do not disrupt the continuity of the chromaticity diagram, or cause different colors to appear the same, they do not lead to color confusion. However, colors with short wavelengths exhibited more changes in color difference when wearing BBLs.

Conclusions

BBLs do not impair the wearer's ability to discriminate colors or perform color vision tests accurately. However, BBLs can cause color differences especially in the recognition of blue hues.

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).

Comparison of visual performances of enhanced monofocal versus standard monofocal IOLs in a mini-monovision approach

PURPOSE

To compare visual performance and quality of life in patients who received either monofocal intraocular lenses (IOLs) or an enhanced monofocal IOL in a mini-monovision target approach.

BACKGROUND

Monofocal lenses are the most common intraocular IOLs employed during cataract surgery because of their relatively low cost and good performance for distance sight. However, these lenses, generally, do not exonerate patients from spectacle use for near or intermediate tasks. On the other hand, enhanced monofocal IOLs (e.g., Tecnis Eyhance®) feature optical properties providing patients with good intermediate visual outcomes. Satisfactory near visual acuity results, regardless of IOL type, may be achieved through mini-monovision. We assessed visual performance outcomes between these IOLs, in a mini-monovision approach.

METHODS

Retrospective case series of patients who underwent bilateral cataract surgery at our institution with implantation of Alcon SN60WF, J&J Tecnis DCB00 or J&J Tecnis Eyhance® DIB00 with a pre-operative mini-monovision target. The postoperative spherical equivalent was measured by a Nidek® auto-refractometer. Best-uncorrected binocular visual acuity (BUBVA) at far (3 m), intermediate (66 cm), and near (40 cm) distance and binocular contrast sensitivity (100%, 25%, and 5%, all at 1 m) were measured using Snellen and Pelli-Robson charts, respectively. Visual performance in daily life was evaluated with the Cataract VF-14 quality of life survey.

RESULTS

71 patients (35 in the monofocal IOL and 37 enhanced IOL group) were enrolled. Patients implanted with enhanced IOL exhibited statistically significant better BUBVA results at 66 cm and 40 cm distances compared to patients in the monofocal group. Additionally, patients in the enhanced IOL group presented a better contrast sensitivity in lower contrast conditions (5%) than patients with monofocal IOL. The quality of life survey showed statistically significant higher scores in daily activities without spectacles for patients with enhanced IOL.

CONCLUSION

Enhanced monofocal IOLs, combined with a mini-monovision approach, provided patients with good visual performance at all tested distances, with superiority of enhanced monofocal IOLs at near and intermediate distances.

A review of the current state of research on artificial blue light safety as it applies to digital devices

Light is necessary for human health and well-being. As we spend more time indoors, we are being increasingly exposed to artificial light. The development of artificial lighting has allowed us to control the brightness, colour, and timing of our light exposure. Yet, the widespread use of artificial light has raised concerns about the impact of altering our light environment on our health. The widespread adoption of personal digital devices over the past decade has exposed us to yet another source of artificial light. We spend a significant amount of time using digital devices with light-emitting screens, including smartphones and tablets, at close range. The light emitted from these devices, while appearing white, has an emission spectrum with a peak in the blue range. Blue light is often characterised as hazardous as its photon energy is higher than that of other wavelengths of visible light. Under certain conditions, visible blue light can cause harm to the retina and other ocular structures. Blue light can also influence the circadian rhythm and processes mediated by melanopsin-expressing intrinsically photosensitive retinal ganglion cells. While the blue component of sunlight is necessary for various physiological processes, whether the low-illuminance artificial blue light emitted from digital devices presents a risk to our health remains an ongoing area of debate. As technological advancements continue, it is relevant to understand how new devices may influence our well-being. This review examines the existing research on artificial blue light safety and the eye, visual performance, and circadian functions.

The Long-Term Effect of Blue-Light Blocking Spectacle Lenses on Adults’ Contrast Perception

Purpose

To evaluate the long-term effect of two different degrees of blue-light blocking (BB) spectacle lenses on adults’ contrast perception under various lighting conditions.

Methods

In total, 144 healthy adults aged 24.70 (±4.32 years) were recruited to this randomized controlled trial. The participants were randomly divided into three groups and used three different spectacle lenses (15% BB: 15% blue-blocking spectacle lenses; 30% BB: 30% blue-blocking spectacle lenses; RC: regular clear lenses serving as control). Contrast sensitivity under four light conditions (scotopic and photopic, both with/without glare) was measured using standard clinical tests at baseline, 1 month, 3 months and 6 months of use. The area under the log contrast sensitivity function (AULCSF) was also computed as an index for their overall contrast sensitivity across spatial frequencies.

Results

There was no significant difference in AULCSFs among the three types of spectacle lenses under any light condition (all P > 0.81). No statistical difference was found in the AULSCF among the four time points (all P > 0.39), with no interaction between the effects of group and time (all P > 0.42).

Conclusion

Wearing blue-light blocking lens had no clinically significant effect on adults’ long-term contrast perception under scotopic or photopic conditions, or with 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.