A Clearer Have a look at the Rise of Myopia

The human eye responds rapidly to changing light and distance. Based on this, scientists hypothesized that focusing on close-up objects in dim environments has driven the rise in myopia.

The human race is becoming increasingly short-sighted. That’s not a comment on political or economic progress, but a reflection on the growing rates of the eye condition myopia, also called nearsightedness. People with this condition have slightly stretched eyeballs, which makes it difficult to focus on distant objects.

In the year 2000, 23 percent of the human population was nearsighted. By the year 2050, that is projected to more than double, and half of the world’s population will need glasses, contact lenses, or surgery to help them see into the distance.¹ Already, nearly 90 percent of young adults in East and Southeast Asia have the condition.² While genetic factors are likely involved, researchers believe that some contributions from our environment are stoking these rapid rises.

While scientists have routinely blamed this myopia epidemic on the excessive use of screens, especially among young people, the fine details of why myopia has surged have remained blurry.

A new study, published in Cell Reports, suggests the cause is slightly more complicated: focusing on close-up objects in low-light environments has driven the rise in myopia.³

“Our findings suggest that a common underlying factor may be how much light reaches the retina during sustained near work—particularly indoors,” said Jose-Manuel Alonso, a visual neuroscientist at State University of New York (SUNY) and coauthor of the new study in a statement.

Accommodating a New Theory of Myopia

In their paper, Alonso and his colleagues asked 13 normal-sighted and 21 nearsighted volunteers to view dark- or light-colored targets through a lens that defocused the targets by minus five diopters (equivalent to looking through a thick pair of glasses). They studied how neural activity patterns in the eye, known as the ON and OFF pathways, responded to the images. ON pathways activate in bright light, and OFF pathways activate in dim light.

The researchers wanted to explore how these pathways affect the physical changes in the eye known as accommodation. During accommodation, the lens shape adjusts subtly to alter its thickness, allowing the eye to maintain focus.

The researchers found that accommodative pupil restriction increased when participants focused on objects very close to them or used the excessively strong negative lenses. The accommodation effects were even stronger in myopic participants.

These effects combine to greatly reduce the amount of light reaching the retina. “In bright outdoor light, the pupil constricts to protect the eye while still allowing ample light to reach the retina,” said Urusha Maharjan, an optometry researcher and study coauthor in the 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.”

Eye Drops and Distance Could Prevent Myopia

The researchers’ theory suggests that poor retinal illumination directly worsens myopia. Importantly, the theory proposes that if the eye is regularly exposed to bright light and long distances, myopia could be prevented. Atropine drops, which block the muscles that constrict the pupils, may also help.

The researchers say their theory remains speculative and that future tests will be needed to confirm it. “This is not a final answer,” said Alonso. “But the study offers a testable hypothesis that reframes how visual habits, lighting, and eye focusing interact.”