The nearsightedness explosion may be fueled by dim indoor light, not just screens
For years, the sharp rise in myopia — or nearsightedness — has largely been blamed on growing screen use,
For years, the sharp rise in myopia — or nearsightedness — has largely been blamed on growing screen use, particularly among children and young adults. However, new research from scientists at the SUNY College of Optometry suggests the explanation may be more nuanced. A study scheduled for publication in Cell Reports proposes that myopia may be influenced less by screens themselves and more by a common indoor behavior: extended close-up focusing in dim lighting, which reduces the amount of light reaching the retina.
“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 (nearsightedness) causes distant objects to appear blurry and has become increasingly common around the globe. 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. Although genetics contribute to risk, the rapid rise over just a few generations points strongly to environmental influences.
In laboratory research, myopia can be triggered in animal models through visual deprivation or the use of negative lenses, and these two methods are believed to involve different neuronal pathways. Doctors also slow myopia progression using multiple strategies that likely act through separate biological mechanisms (multifocal lenses, ophthalmic atropine, contrast-reduction, promoting time outdoors, and others). Researchers at the State University of New York (SUNY) College of Optometry now suggest there may be a single neuronal explanation that connects these different methods of both inducing and controlling myopia.
A New Theory About Retinal Light and Eye Focus
This new hypothesis attempts to solve 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 seem to affect how myopia progresses?
“In bright outdoor light, the pupil constricts to protect the eye while still allowing ample light to reach the retina,” explained Urusha Maharjan, 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 (i.e., an accommodative 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 prologued periods of time (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.
