The global rise in nearsightedness has largely been attributed to our phone addiction, but researchers now suggest that incessant scrolling is not solely to blame.
A team of scientists from the SUNY College of Optometry found that dim indoor lighting, combined with prolonged, up-close focus, may be straining the eyes. The study, published in Cell Reports, suggests that myopia, or nearsightedness, is not aggravated solely by the use of personal devices.
Up close and dark
Nearsightedness has been rapidly increasing across the world, with current estimates suggesting that it will affect nearly 50% of the global population by 2050. Shortsighted people have slightly stretched eyeballs, making it difficult to focus on distant objects.
Although the increasing number of shortsighted people has largely been linked to excessive use of our phones, the new study suggests it’s not that simple. Instead, focusing on objects up close in low-light environments strains the retina.
“In bright outdoor light, the pupil constricts to protect the eye while still allowing ample light to reach the retina,” Urusha Maharjan, SUNY Optometry doctoral student and lead author of the study, said in a statement. “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.”
Prolonged focus on objects in dim lighting further enhances this pupil constriction, especially for people who are already nearsighted.
Squint season
Myopia may develop when insufficient light reaches the retina during prolonged close focus in dim indoor environments, according to the new study. When the light is too dim, it causes the pupils to narrow excessively at short viewing distances, making it difficult to develop normal vision.
On the other hand, in brightly lit environments, the pupil constricts in response to light rather than focusing distance, maintaining healthy stimulation of the retina.
The theory is speculative and requires further testing to confirm. If it holds up, however, it could have significant implications for preventing nearsightedness. “This is not a final answer,” Jose-Manuel Alonso, a professor at SUNY and co-author of the study, said in a statement. “But the study offers a testable hypothesis that reframes how visual habits, lighting, and eye focusing interact.”
Correction: An earlier version of this article incorrectly made note of reading glasses. The condition described here is myopia, which requires glasses for distance.