Global Myopia Epidemic Linked to Dim Indoor Lighting, Study Suggests

Nearsightedness is reaching unprecedented levels worldwide, with the World Health Organization projecting nearly half of the global population will be myopic by 2050. While digital device use has long been implicated, new research suggests poor indoor lighting may play a significant role in this growing public health concern.

A groundbreaking study from the State University of New York (SUNY) College of Optometry has identified a specific mechanism that may trigger myopia development. The research challenges conventional understanding by suggesting it’s not the devices themselves causing the problem, but rather the lighting conditions in which they’re typically used.

Nearsightedness occurs when the eyeball becomes elongated, causing light to focus in front of the retina rather than directly on it, according to the American Optometric Association. This physical change makes distant objects appear blurry while close-up vision remains clear.

“When people focus on close objects indoors, such as phones, tablets or books, the pupil constricts—not because of brightness, but to sharpen the image,” explained Urusha Maharjan, the SUNY Optometry doctoral student who conducted the study. “In dim lighting, this combination may significantly reduce retinal illumination.”

The study’s hypothesis proposes a surprisingly straightforward mechanism: when the retina doesn’t receive adequate light during extended close-up work, it signals the eye to grow. In dimly lit environments, the naturally constricted pupil (which narrows when focusing on nearby objects) allows so little light through that the retina can’t generate a strong enough signal to halt eye growth.

This finding helps explain why outdoor activity has consistently been shown to reduce myopia risk in children. Outdoor environments typically provide light levels 10-100 times brighter than indoor settings, ensuring the retina receives sufficient illumination even when the pupil constricts during close-up focus.

“High-intensity natural light prevents myopia because it provides enough retinal stimulation to override the ‘stop growing’ signal, even when pupils are constricted,” the researchers noted.

The digital device connection still exists but may be indirect. Smartphones, tablets, and computers are typically used indoors in suboptimal lighting conditions, creating the perfect storm for myopia development—especially among children and adolescents whose eyes are still developing.

Current statistics underscore the urgency of addressing this issue. Studies show that combined heavy smartphone and computer use is associated with an 80% higher risk of myopia. As digital device use continues to increase globally, particularly among younger populations, myopia rates are expected to rise correspondingly.

The study’s senior author, Jose-Manuel Alonso, MD, PhD, and SUNY distinguished professor, emphasized that while this research represents a significant step forward, more investigation is needed. “This is not a final answer, but the study offers a testable hypothesis that reframes how visual habits, lighting and eye focusing interact,” he said.

The research team acknowledged some limitations, including the small subject group and technical challenges in measuring internal lens changes, as the bright backgrounds used to simulate outdoor conditions made pupils too small for standard equipment to evaluate effectively.

Despite these limitations, the findings suggest a potentially simple intervention: increasing indoor brightness during close-up work could help slow the global myopia epidemic. This approach would be particularly valuable in educational settings and workplaces where extended near-focus tasks are common.

The study, published in the journal Cell Reports, comes at a critical time as health authorities worldwide grapple with the increasing prevalence of vision problems. If confirmed through further research, these findings could inform public health guidelines and practical interventions to protect vision, particularly among vulnerable populations like children and adolescents.

For parents concerned about their children’s vision, the research suggests maintaining well-lit environments for reading and screen time, while still encouraging regular outdoor activities as a protective measure against myopia development.