“Myopia has reached near-epidemic levels worldwide, yet we still don’t fully understand why,” said Jose-Manuel Alonso, MD, PhD, SUNY Distinguished Professor and senior author of the study. “Our findings suggest that a common underlying factor may be how much light reaches the retina during sustained near work — particularly indoors.”
Myopia Rates Are Climbing Worldwide
Myopia, or nearsightedness, causes distant objects to appear blurry and has become increasingly prevalent globally. It now affects nearly 50 percent of young adults in the United States and Europe, and close to 90 percent in parts of East Asia. While genetics play a role in the risk of developing myopia, the rapid increase over just a few generations strongly indicates environmental influences.
In laboratory research, myopia can be induced in animal models through visual deprivation or the use of negative lenses, which are believed to involve different neuronal pathways. Doctors also employ multiple strategies to slow myopia progression, such as multifocal lenses, ophthalmic atropine, contrast-reduction, and promoting time outdoors, each likely acting through separate biological mechanisms. Researchers at the State University of New York (SUNY) College of Optometry now propose a single neuronal explanation that may connect these diverse methods of inducing and controlling myopia.
A New Theory About Retinal Light and Eye Focus
This new hypothesis seeks to address a long-standing question in vision science: why do such varied factors, from close-up work and dim indoor lighting to treatments like atropine drops, multifocal lenses, and increased time outdoors, all appear to influence myopia progression?
“In bright outdoor light, the pupil constricts to protect the eye while still allowing ample light to reach the retina,” explained Urusha Maharjan, a SUNY Optometry doctoral student who conducted the study. “When people focus on close objects indoors, such as phones, tablets, or books, the pupil can also constrict, not because of brightness, but to sharpen the image. In dim lighting, this combination may significantly reduce retinal illumination.”
Under this proposed mechanism, myopia may develop when insufficient light reaches the retina during sustained close-up work in low-light settings. If lighting is too dim and the pupil narrows excessively at short viewing distances, retinal activity may not be strong enough to support normal visual development. In contrast, exposure to bright light allows the pupil to constrict in response to brightness rather than focusing distance, helping maintain healthier retinal stimulation.
How Accommodation and Negative Lenses Play a Role
The study also found that negative lenses decrease retinal illumination by causing the pupil to narrow through accommodation—an increase in the lens power of the eye when focusing images at short distances. This narrowing intensifies when viewing distance is shortened or when overly strong negative lenses are worn. It becomes even more pronounced when accommodation is sustained for prolonged periods (e.g., tens of minutes), and increases further once the eye has already become myopic. Researchers also observed additional disruptions in eye turning during accommodation and reduced effectiveness of eye blinks in triggering pupil constriction in myopic eyes.
Implications for Myopia Prevention and Treatment
If validated, this proposed mechanism could significantly change how scientists and clinicians think about myopia progression. The theory suggests that maintaining safe exposure to bright light while limiting accommodative pupil constriction may help control myopia. That reduction in constriction can be achieved by lowering accommodative demand with lenses (multifocal or contrast-reduction), directly blocking the muscles responsible for pupil constriction (atropine drops), or spending time outdoors without engaging accommodation (looking at far distances).
Importantly, the researchers predict that any treatment approach may be less effective if individuals continue prolonged close-up focusing indoors under dim lighting conditions.
“This is not a final answer,” Alonso emphasized. “But the study offers a testable hypothesis that reframes how visual habits, lighting, and eye focusing interact. It’s a hypothesis grounded in measurable physiology that brings together many pieces of existing evidence. More research is needed, but it gives us a new way to think about prevention and treatment.”
The study was conducted by Urusha Maharjan and colleagues in the laboratories of Jose-Manuel Alonso at the SUNY College of Optometry.
