Refractive
July 2023
by Ellen Stodola
Editorial Co-Director
Daniel Chang, MD, and George Waring IV, MD, have studied and used light-blocking and light-filtering IOL technology in clinical practice, and they discussed the concepts behind blocking and filtering certain violet and blue light.
Dr. Chang said Alcon popularized the idea of short wavelength/high energy light filtering with its Natural chromophore more than 15 years ago. This was a blue light filter, and it was marketed as a feature for macular protection. There have been studies looking at this chromophore and its potential impact on contrast and tolerance to dysphotopsias, bright lights, and challenging lighting conditions, he said.
Johnson & Johnson Vision received FDA approval for its OptiBlue chromophore as well. OptiBlue is now a key enabling technology of the InteliLight portfolio, which recently launched with the Tecnis Synergy and Tecnis Symfony OptiBlue with InteliLight IOLs, Dr. Chang said. He was an investigator on the original clinical trials for OptiBlue back in 2006, now published.1 The technology was studied in monofocal IOLs, and it was shown to decrease difficulty with driving in both day and nighttime conditions, and there was less frustration with vision, Dr. Chang said. Subsequently, Johnson & Johnson Vision added this technology to its range of vision lens portfolio to reduce dysphotopsias at nighttime as well.
Dr. Waring has also evaluated light-filtering technology. “Recently we have had an evolution in IOL technology with the advent of the first violet light-filtering IOL available in the U.S. as part of the InteliLight portfolio,” Dr. Waring said. “This is an improvement in IOL performance for better quality of vision and mitigation of dysphotopsia.”
Violet light filtration is designed to mitigate halo, glare, and starbursts, resulting in fewer disturbances during nighttime activities, Dr. Waring said. In addition, the achromatic technology corrects for chromatic aberrations for improved contrast, and the high resolution echelette design reduces light scatter and halo intensity. Dr. Waring and Dr. Chang were two of the first surgeons in the U.S. to have pre-market access to the Tecnis Symfony OptiBlue with InteliLight. “We performed an informal pilot evaluation in a contralateral series of patients with legacy Symfony in one eye and Tecnis Symfony OptiBlue with InteliLight, or the violet light filter, in the other eye, and with non-directed questioning, the patients noticed less dysphotopsia in the eye with Tecnis Symfony OptiBlue with InteliLight,” he said. “It seemed to be that there was more of an improvement in the starburst type of dysphotopsia in particular.”
Dr. Waring explained that low wavelength visible light is becoming more prevalent with LED lights. “We see that with violet filtration, which is in a shorter wavelength than blue light filtration,” he said. Violet light produces the most scatter, and it turns out that violet filters reduce halo intensity as well. “In the pilot and original studies comparing the Tecnis violet with clear, it was seen that nighttime driving was statistically better with a violet filtration,” he said. “There are other benefits of blocking violet where we might want to preserve blue light.” This can regulate circadian rhythms, which is beneficial for sleep and cognitive function.
Dr. Waring said that this aids in low-light contrast, and it has been used in diffractive presbyopia-correcting IOLs in the U.S. before. There is better nighttime performance and better image quality because of better contrast sensitivity in general. Dr. Waring added that it’s important to mention that blue light is defined as between 450–500 nanometers (nm) in wavelength, and violet light is shorter than 450 nm in wavelength and is typically associated with higher degrees of light scatter.
Dr. Chang noted some recent work on the topic of high energy light filtration. The first is a paper published in the Journal of Ophthalmic Studies that looked at the broad and diverse impact of high energy light.2 “We broke down the issues into three areas: vision, macular protection/potential retinal phototoxicity protection, and general health (circadian rhythm),” he said. We realized that the literature on high energy light filtration is vague, Dr. Chang said. “High energy, blue, and violet light are frequently grouped together, but it’s important to differentiate the specific wavelengths being filtered because that can affect real-world performance.
“When you put a chromophore in the eye, patients will look through it for the rest of their lives. If the particular chromophore is transmitting too much light, they can easily put on sunglasses, but if a chromophore blocks a percentage of useful light, the patient will never be able to recover that. Therefore, it’s better to filter out what is always bad and transmit what may sometimes be good. To do this effectively, one must consider narrow wavelength bands, 10 nm segments, when looking at the filter,” Dr. Chang continued.
Dr. Chang said that visual performance is the most important consideration when selecting a chromophore. He recently co-authored a laboratory study looking at the effect of a violet light filter on clinical performance of the Tecnis Symfony.3 The study showed a 19% improvement in halo performance, up to 17% reduction in retinal veiling luminance (glare, halos, and starbursts), and up to 13% improvement in contrast under challenging light conditions.
This aligns with a retrospective study that he presented at the 2022 ASCRS Annual Meeting, in which he compared the clinical performance of Tecnis Symfony OptiBlue with InteliLight to colorless Tecnis Symfony.4 He demonstrated up to 45% reduction in dysphotopsia complaints and up to 72% reduction in postoperative dysphotopsia counseling in patients with Tecnis Symfony OptiBlue with InteliLight.
Chromatic aberration can significantly degrade visual quality. The proper chromophore can potentially lessen the negative effects of chromatic aberration from a lens with low Abbe number (high chromatic aberration) by filtering out high energy, short wavelength light that may be out of focus due to the high dispersion. Nevertheless, starting with a high Abbe number material with low dispersion and low chromatic aberration is still the preferred approach.
Scotopic vision requires participation of rod photoreceptors, which are sensitive to blue light. Filtering out that blue light can reduce scotopic or low light vision. The ideal chromophore would filter violet and not blue light, protecting scotopic vision while reducing dysphotopsias.
When looking at retinal photoprotection, Dr. Chang said, the shorter the wavelength, the higher the energy, and the more damage it can do. In general, wavelengths in the range of 410 nm and below have increasingly greater toxicity. Ultraviolet light is 380 nm and below.
“Both higher energy violet and blue light can have some potential phototoxicity effects,” he said. But since blue light can impact functional vision, you would prefer to filter it with a pair of sunglasses. You want to make sure you’re only blocking the primarily negative wavelengths in the eye.
Finally, with circadian rhythm, Dr. Chang said there are the intrinsically photosenstive retinal ganglion cells, which have sensitivity in the blue light spectrum. When you wake up in the morning to a lot of blue light, this increases melanopsin production and inhibits melatonin production. The idea is to reduce blue light exposure as the day goes on to help maintain circadian rhythm. Blocking blue light may thus interfere with circadian rhythm function.
Looking at the absorption spectrum, the AcrySof IOL (Alcon) blue light-filtering chromophore filters up to a third of blue light wavelengths, and because it has a broad spectrum range, filtration depends on the IOL power, so it’s not consistent. The Johnson & Johnson Vision violet light-filtering chromophore has a steep peak. More importantly, you’re keeping blue and filtering violet, Dr. Chang said. The Alcon chromophore filters out blue light, which potentially could affect scotopic vision and circadian rhythm, but it doesn’t filter out all of the high energy violet light, with up to 25% of the 410 nm violet still being transmitted vs. 0% for the Johnson & Johnson Vision chromophore.
In a presentation that looked at the theoretical comparative impact of a violet vs. blue light filter, Dr. Chang shared data showing the Johnson & Johnson Vision violet light filter having less decrease in scotopic vision, less impact on circadian rhythm, and the same amount of macular photoprotection.5
Dr. Waring said he has largely moved to violet filtration for presbyopia-correcting IOLs, but he added that InteliLight is reserved for diffractive presbyopia-correcting IOLs. Johnson & Johnson Vision is currently the only manufacturer to offer this, and it is not offered in a monofocal or monofocal toric. “More patients are seeking presbyopia correction, but those who are not a candidate would still benefit from violet filtration in the monofocal and monofocal toric.”
Dr. Waring emphasized that the benefit of violet filtration for low light contrast sensitivity is typically the most challenging visual environment, in particular with diffractive presbyopia-correcting IOLs. The violet filtration helps by reducing light scatter and improving image quality, improving low light contrast, improving low light reading performance, and mitigating and reducing dysphotopsias, he said.
In terms of patients for whom high energy light filtering would be most beneficial, Dr. Chang said that while there are many potential benefits, demonstrating them clinically can be challenging. “Traditional clinical vision tests are simply not designed to study the visual impact of high energy light filters, much less differentiate them.” As an example, the emission spectra of lighting or glare sources used in vision tests are not routinely characterized. Warmer vs. cooler lights, fluorescent vs. LED lights, white vs. monochromatic light may all impact testing results, particularly when considering the effect of a chromophore, yet few studies even consider these factors. There have been some population-based epidemiological studies, but it’s hard to isolate the impact of the chromophore alone. “Part of the problem is blue light-filtering has become a marketing concept,” he said. “The challenge is to address the topic with enough specificity for relevance without so much complexity that people are unable to follow.”
Dr. Chang said he would be interested to learn more on this topic through further studies. Fundamentally, clinical testing of vision is quite limited, he said. Our vision tests were not created to understand visual quality in real-world contrast and lighting conditions, which are key to understanding IOL performance. For now, he said it’s important to increase awareness that high energy light filtering is about more than just macular protection and more than just marketing hype.
About the physicians
Daniel Chang, MD
Cataract and Refractive Surgeon
Empire Eye and Laser Center
Bakersfield, California
George Waring IV, MD
Waring Vision Institute
Mt. Pleasant, South Carolina
References
- Chang DH, et al. Clinical evaluation of a modified light transmission short-wavelength filtering intraocular lens compared to a colorless control. Ophthalmol Ther. 2023;12:1775–1785.
- Chang DH, et al. Violet and blue light: impact of high-energy light on vision and health. J Ophthalmic Stud. 2020;3. E-pub.
- van der Mooren M, et al. Effect of violet light-filtering and manufacturing improvements in an extended depth-of-focus intraocular lens on visual performance. Clin Ophthalmol. 2023;17:701–709.
- Chang DH, et al. The effect of violet light filtration and manufacturing improvements on the clinical performance of an extended depth of focus IOL. Presentation at the 2022 ASCRS Annual Meeting, Washington, D.C.
- Chang DH, et al. Violet light-filtering IOLs: visual and non-visual benefits. Presentation at the 2020 American Academy of Ophthalmology Annual Meeting, virtual.
Relevant disclosures
Chang: Johnson & Johnson Vision
Waring: Johnson & Johnson Vision
Contact
Chang: dchang@empireeyeandlaser.com
Waring: georgewaringiv@gmail.com
