Study suggests short-sightedness caused by how we use our eyes indoors

By Stephen Beech

Short-sightedness is driven by how we use our eyes indoors, suggests a new study.

The common condition – also known as myopia – may be driven less by screens and more by a common indoor visual habit, say American scientists.

For years, rising rates of myopia have been attributed to increased screen time, especially among children and young adults.

But new research by scientists at the State University of New York (SUNY) College of Optometry suggests the story may be more complicated – and more human.

Their findings hint that myopia may be on the rise due to prolonged close-up focus in low-light environments, limiting how much light reaches the retina.

Study senior author Professor Jose-Manuel Alonso said: “Myopia has reached near-epidemic levels worldwide, yet we still don’t fully understand why.

“Our findings suggest that a common underlying factor may be how much light reaches the retina during sustained near work – particularly indoors.”

He explained that myopia blurs vision at far distance and is becoming a world epidemic, affecting nearly half of young adults in Europe and US and close to 90% in parts of East Asia.

While genetics play an important role, Alonso says rapid increases over just a few generations suggest environmental factors are also critical.

He said the disease can be induced in animal models with visual deprivation or negative lenses, and the two induction processes are thought to involve different neuronal mechanisms.

Opticians control the progression of myopia using a range of approaches that are thought to engage multiple mechanisms

Scientists at SUNY College of Optometry propose a unifying neuronal mechanism to explain all current approaches to myopia induction and control.

The research offers a new hypothesis that could help explain why so many seemingly different factors – from near work and dim indoor lighting to treatments such as multifocal lenses – all appear to influence myopia progression.

Study lead author Urusha Maharjan, a SUNY doctoral student, said: “In bright outdoor light, the pupil constricts to protect the eye while still allowing ample light to reach the retina.

“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.”

She explained that, according to the mechanism, myopia develops when poor retinal illumination fails to generate robust retinal activity because the light sources are too dim and pupil constriction is too excessive at short viewing distances.

Conversely, myopia doesn’t develop when the eye is exposed to bright light and the pupil constriction is regulated by image brightness instead of viewing distance.

The new study, published in the journal Cell Reports, shows that negative lenses reduce retinal illumination by constricting the pupil through a process known as accommodation.

Such pupil constriction becomes stronger when accommodation is increased by shortening viewing distance or wearing excessively-strong negative lenses.

And pupil constriction becomes even stronger when lens accommodation is sustained for extended periods of time, and even stronger when the eye becomes myopic.

If proven correct, the researchers say the mechanism proposed could lead to a “paradigm shift” in the understanding of myopia progression and control.

It suggests myopia can be controlled by exposing the eye to safe bright light levels under limited accommodative pupil constriction.

Alonso says accommodative pupil constriction can be limited by reducing accommodation strength with lenses, blocking directly the muscles driving pupil constriction, or by simply spending time outdoors without looking at far distances.

He says the new mechanism also predicts that any approach to myopia control will fail if the eye is exposed to excessive accommodation indoors under low light for prolonged periods of time.

Alonso said: “This is not a final answer.

“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.”

He added: “More research is needed, but it gives us a new way to think about prevention and treatment.”