More and more people worldwide are suffering from myopia. Screen work is a possible trigger. A study now suggests that it’s less the screens themselves that are the problem, but rather focusing on close objects in low-light environments. Accordingly, when working closely indoors, the pupils constrict excessively to enable sharp vision, but in doing so, too little light falls on the retina. As a result, the visual pathways are activated unevenly and weakened over time. Good lighting and regular time outdoors looking into the distance can help counteract myopia.
If you are nearsighted, you can only see objects in the distance blurred. In Germany, around one in three people is affected, and in parts of East Asia even almost 90 percent of young adults are affected. The proportion is increasing sharply, especially among children and young people. “Myopia has reached near-epidemic proportions worldwide, but we still don’t fully understand why,” says senior author Jose-Manuel Alonso of the State University of New York. Even if genetic factors play a role, they cannot explain why the problem has worsened so rapidly in just a few generations. A lot of time spent on screens is often discussed as the cause, but the possible mechanisms for this are still unclear.
Work for the eyes
Together with a team led by first author Urusha Maharjan, Alonso has now researched how our eyes react to close visual stimuli and which processes may promote myopia. To do this, the researchers asked 21 short-sighted and 13 normal-sighted volunteers to focus on a small square with one eye. Using an electrically adjustable lens, the team blurred the square so that subjects had to strain their eyes to see it clearly again. During this so-called accommodation, the eye muscles ensure that the lens thickens and images close objects more sharply. The pupil contracts for additional sharpness. In addition, the two eyes move towards each other to focus on the close object.
While the test subjects successively focused on numerous light and dark squares with different contrasts to the background, the researchers measured the changes in pupil size and eye position and also recorded the extent to which the different visual pathways were activated. Some nerve cells in the retina react to light, others to darkness. These so-called ON and OFF visual pathways process brightness contrasts differently and transmit the signals separately to the brain.
Too little light on the retina
This showed that the more the test subjects had to work to focus on the square, the more their eyes moved towards each other and the narrower their pupils became – regardless of the absolute brightness. In dim lighting, this meant that only a small amount of light fell on the retina through the constricted pupils. Accordingly, the light-responsive ON pathways were less activated compared to the OFF pathways. In nearsighted people, all observed effects were significantly more pronounced: their pupils constricted more and their OFF pathways, which react to darkness, were more dominant than the ON pathways.
According to the study, this could be exactly where the problem lies: the uneven activation of the nerve pathways could promote long-term structural changes in the eye, including excessive linear growth of the eyeball – the physiological cause of myopia. “This mechanism could explain why myopia increases during activities that maximize pupil constriction, such as close work,” the research team writes. At the same time, the results also point to prevention options. Regular stays outdoors, where you can relax and gaze into the distance, can help preserve your eyesight. When doing indoor activities, however, adequate lighting is crucial so that enough light falls on the retina, even when the pupil constricts.
“Our study does not provide a definitive answer, but does provide testable hypotheses that redefine the interactions between viewing habits, lighting and eye focusing,” says Alonso. “More research is needed, but it gives us a new way of thinking about prevention and treatment.”
Source: Urusha Maharjan (State University of New York College of Optometry, USA) et al., Cell Reports, doi: 10.1016/j.celrep.2026.116938