Biotechnology

A new lens analysis approach could improve treatments for nearsightedness

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A new lens analysis approach could improve treatments for nearsightedness
Instrumentation recreates the nature of myopic eyes to test lenses that prevent vision loss

A new lens analysis approach could improve treatments for nearsightedness
Instrumentation recreates the nature of myopic eyes to test lenses that prevent vision loss

WASHINGTON — Researchers have developed a new instrument to rigorously measure and compare the light-focusing properties of special eyeglass lenses used to slow the progression of myopia, or nearsightedness. The information obtained with this new approach could help inform future lens designs that are even more effective at preventing vision loss.

Nearsightedness is on the rise worldwide, especially among children. If current trends continue, half of the world’s population will be nearsighted by 2050, according to a report from the Brien Holden Vision Institute in Australia. Although the drivers of this worrying trend are not entirely clear, special eyeglass lenses have been shown to prevent myopia from getting worse. This is especially important for children and adolescents who often experience developmental conditions as their bodies grow.

In the OPTICALthe Optica Publishing Group journal for high-impact research, researchers from the ZEISS Vision Science Lab at the University of Tübingen, in Germany, and the University of Murcia, in Spain, describe their new instrument, which measures lens performance under real-world viewing conditions. They also report results from measuring the light focusing characteristics of various lenses used to slow the progression of myopia.

“Insights into the relationship between the optical properties of the lens in the management of myopia progression and effectiveness in real-world scenarios will pave the way to more effective treatments,” said study author Augusto Arias-Gallego, from the ZEISS Vision Science Lab. “This can help millions of children and is fundamental in understanding the mechanism of action of this lens.”

Capture real-life viewing conditions
Myopia is usually caused when a person’s eyes become slightly elongated. This causes distant objects to appear blurry because they are focused in front, not on the retina. While traditional eyeglass lenses can correct this blurring, they do not prevent myopia from getting worse. The development of myopia can increase the chance of other eye problems and permanent blindness.

Lenses that modify retinal signaling to reduce myopia progression have been clinically tested and are currently available on the market. Researchers hypothesize that this lens slows the growth of the eyeball, preventing it from becoming more elongated. These lenses incorporate different types of structures, such as microlenses or microdiffusers, to manipulate image properties in the peripheral retina while correcting central vision. However, the optical properties of this relatively new technology have not been extensively studied and compared.

In the new work, the researchers wanted to thoroughly characterize currently available lenses under real-world viewing conditions. “After exploring its sophistication, we did not find a method that could be used to characterize the optical properties of these spectacle lenses under real viewing conditions,” said Arias-Gallego. “Therefore, we developed a new instrument that can measure the optical response of the lens to different lighting angles while reproducing myopic pupils and refractive errors.”

This new instrument uses an illumination source mounted on an arm that rotates around the lens. After light passes through the lens, a rudder mirror guides it toward a spatial light modulator (SLM), which consists of tiny liquid crystal cells that modify the traveling light with high spatial resolution.

The SLM is the heart of the instrument because it reproduces the refractive error and the shape of the pupil of a myopic eye. This allowed the researchers to reproduce, for the first time, the apparent aberrations produced by different lighting angles for different myopic eyes when testing the lenses. The deviations are programmed as a phase map using the SLM.

In addition, programmed defocus can be induced with SLM, which allows researchers to perform through-focus testing. This test captures image quality in the proximity of a simulated retinal position, highlighting how the lens interacts with signaled eye elongation on the retina.

The researchers also calculated the light scattering properties of the lenses, which is important because one of the lenses tested was based on reducing contrast by adding scatter. For this, they devised a special setup that does not require the special detectors and moving parts conventionally required for scattering quantification.

Compare lens properties
“By combining through-focus results with light scattering measurements, we can accurately characterize several types of eyeglass lenses,” said Arias. “We then compared our measurements for each lens with their reported clinical efficacy for slowing myopia progression. The results raise new questions that need further study while also indicating potential strategies that can increase the effectiveness of future designs.”

In this work, lenses are characterized using a single wavelength of light to simplify the analysis of image properties. Because illumination in real scenarios contains multiple wavelengths, the researchers worked to adapt the instrument to include sources with different wavelengths.

Paper: A. Arias, A. Ohlendorf, P. Artal, S, Wahl, “In-depth optical characterization of spectacle lenses for the management of myopia progression,” 10, 5 (2023). DOI: 10.1364/OPTICA.486389.

ZEISS Vision Science Lab is the “Industry on Campus Professorship” working group at the University of Tübingen. As part of the University Excellence Initiative, new collaborative projects with industry are being launched at the lab, focused on application-inspired research in the fields of myopia, presbyopia and artificial intelligence.

About OPTICAL
OPTICAL is an open access journal dedicated to the rapid dissemination of high-impact peer-reviewed research across the optical and photonic spectrum. Published monthly by the Optica Publishing Group, the Journal provides a forum for pioneering research to be quickly accessed by the international community, be it theoretical or experimental, fundamental or applied research. OPTICAL maintains a distinguished editorial board of more than 60 associate editors from around the world and overseen by Editor-in-Chief Prem Kumar, Northwestern University, USA. For more information, visit OPTICAL.

About Optica Publishing Group (formerly OSA)

Optica Publishing Group is a division of Optica (formerly OSA), Advancing Optics and Photonics Worldwide. It publishes the largest collection of peer-reviewed content in optics and photonics, including 18 prestigious journals, society’s flagship member magazines, and papers from more than 835 conferences, including 6,500+ related videos. With more than 400,000 journal articles, conference papers, and videos to search, find, and access, the Optica Publishing Group represents research in this field from around the world.

Media Contact:
Aaron Cohen
(301) 633-6773
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