Effect of Individualized Ocular Refraction Customization Spectacle Lenses on Astigmatism in Myopic Children
This two-year study demonstrates that individualized ocular refraction customization (IORC) spectacle lenses do not induce clinically meaningful or dose-dependent changes in corneal or refractive astigmatism in myopic children, supporting their optical safety.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
For millions of children around the world, the eyes are slowly losing their ability to focus on distant objects, a condition known as myopia. As the eye grows too long from front to back, light focuses in front of the retina instead of directly on it, creating a blurry image. While glasses can correct the blur, rapid eye growth carries serious risks later in life, including retinal detachment and other sight-threatening complications. To slow this growth, eye doctors have turned to special spectacle lenses that alter how light enters the eye. These lenses are designed to create a specific optical signal in the peripheral vision, essentially telling the eye to stop growing as fast. However, because every eye has a unique shape and curvature, a standard lens design might not work perfectly for every child. This has led researchers to develop personalized lenses that are custom-made to match the specific optical profile of each child's eye. But as these complex, custom lenses become more common, a new question arises: could the very features designed to stop eye growth inadvertently change the shape of the cornea, the clear front window of the eye, in ways that create new vision problems?
A team of researchers at West China Hospital of Sichuan University set out to answer this question by tracking a group of children over two years. They recruited 184 children between the ages of 8 and 12 who already had myopia. In the first year of the study, the children were randomly assigned to wear one of four types of glasses. Three groups wore the new personalized lenses, but each group received a different strength of the special peripheral signal: a high strength, a medium strength, or a low strength. The fourth group wore standard, single-vision glasses that offered no special growth-slowing signal. The goal was to see if the strength of the signal in the personalized lenses caused the astigmatism, or the irregular curvature of the eye, to change differently than in the standard glasses. After one year, every child in the study, regardless of which group they started in, switched to the high-strength personalized lens for the second year. This design allowed the researchers to observe how the eyes reacted to the lenses over time and whether the initial treatment left a lasting mark on the eye's shape.
The researchers measured the children's eyes every few months, paying close attention to two types of astigmatism. One type comes from the cornea itself, and the other is the total astigmatism the child experiences when looking through a lens, which includes the cornea and the internal structures of the eye. They tracked these measurements using a mathematical system that breaks down the curvature into two main directions: one that runs vertically and horizontally, and another that runs diagonally. Over the course of the study, they found that the eyes of the children did change slightly, but these changes were consistent across all groups, whether they wore the high-strength personalized lenses, the low-strength ones, or the standard glasses. Specifically, the vertical and horizontal curvature of the cornea shifted very slowly in a predictable direction, increasing by less than one-tenth of a diopter per year. This small shift is a natural part of how eyes develop during childhood and is not caused by the glasses. The diagonal curvature remained completely stable, showing no signs of the irregular changes that would suggest the lenses were warping the eye.
Crucially, the study found no evidence that the strength of the personalized lens mattered. The children who wore the high-strength lenses did not experience different changes in their eye shape compared to those who wore the low-strength lenses or the standard glasses. Even when all the children switched to the high-strength lens in the second year, the rate of change in their eye shape did not suddenly speed up or slow down. This suggests that the lenses are optically safe and do not force the cornea to remodel itself in response to the treatment. While the researchers did notice a moderate link between the growth of the eye and changes in the total astigmatism, this connection was not seen with the cornea alone. This indicates that the changes observed were likely due to the natural, coordinated adjustments of the entire eye system as it grows, rather than a direct effect of the lenses reshaping the cornea.
By the end of the two years, the vast majority of children showed only tiny shifts in their astigmatism. Less than five percent of the eyes showed a change large enough to be considered clinically significant, and this small number was the same across all groups. The findings provide strong reassurance that these advanced, custom-made lenses can be used to slow down myopia without introducing new, unintended vision problems. The study confirms that the personalized approach, which tailors the lens to the individual child, does not create a dose-dependent risk where stronger signals lead to greater changes in eye shape. For parents and eye care professionals, this means that the pursuit of better myopia control through personalized optics does not come at the cost of altering the fundamental shape of the eye in a harmful way. The lenses appear to work as intended, guiding the eye's growth without distorting its surface.
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