Is Dim Indoor Light Fueling The Nearsightedness Boom?

Nearsightedness (myopia) has exploded in recent decades. In many countries, a large share of teenagers and young adults now need glasses or contact lenses to see clearly at a distance. For years, most of the blame has been put on phones, tablets and computers.

New research suggests the picture may be more complicated. It may not just be the screens themselves, but the combination of prolonged close‑up work in dim indoor light that puts extra strain on growing eyes.

Why researchers are looking beyond “too much screen time”

When we are outside, daylight is usually far brighter than normal room lighting. Even though our pupils get smaller to protect the eye, plenty of light still reaches the retina. Indoors, especially in soft or low lighting, things are different.

When you focus on something up close – a book, phone or laptop – your eyes adjust their focus and your pupils tend to constrict. If the room is already dim, that focusing response can mean that very little light is actually reaching the back of the eye.

The new work proposes that this mix of long stretches of close focus + small pupils + weak ambient light might reduce the amount of retinal stimulation in a way that encourages the eye to become more myopic over time. It offers a single explanation that could link several things we already know:

• Intense near work appears to raise myopia risk.
• Time spent outdoors in daylight seems to protect children’s eyesight.
• Some lenses and eye‑drop treatments that change how the eye focuses can slow myopia progression.

Focusing, lenses and how light reaches the retina

In the study, researchers modelled how different focusing demands and lenses affect pupil size and retinal light levels. They found that:

• Near focusing for tens of minutes at a time causes the pupils to constrict and reduces the total amount of light hitting the retina.
• Negative lenses (the type used to correct myopia) and short viewing distances increase this effect.
• Eyes that are already myopic appear to behave differently when they focus, which may deepen the problem over time.

The authors suggest that treatments which reduce the effort needed for close focus – such as some multifocal lenses, special contrast‑altering lenses or low‑dose atropine drops – may help in part because they prevent the pupil from clamping down so hard during reading and screen work. That could keep retinal light levels healthier.

At the same time, they argue that any treatment is likely to work better if daily visual habits change as well – meaning less time spent doing close‑up tasks in poor lighting.

Practical steps to protect your eyes (and your kids’)

This is still a theory that needs more testing, but it lines up with existing advice from many eye‑care professionals. The good news is that the suggested changes are simple and low‑risk.

1. Turn up the lights for reading and screen use

• Avoid doing detailed work or scrolling on your phone in very dim rooms.
• Use a decent room light plus, ideally, a desk lamp for reading or computer work.
• Discourage long sessions of reading in bed or on the sofa with only a tiny lamp on.

The idea is to avoid the situation where your eyes are locked on something very close, your pupils are tiny, and the overall light level is low.

2. Build “distance and daylight” breaks into the day

Many studies have shown that children who spend more time outdoors have a lower risk of developing myopia. Bright daylight and looking at distant objects seem to be key.

• For children, aim for at least a couple of hours of outdoor play spread across the day when possible.
• For adults, try to get outside in daylight every day, even if it is just for a short walk.
• Use simple rules like the “20‑20‑20 rule”: every 20 minutes, look at something roughly 6–7 metres away for at least 20 seconds.

3. Avoid marathon near‑work sessions in one go

The new theory points to long, uninterrupted periods of close focus in dim light as especially unhelpful. To break this pattern:

• Encourage children to take regular breaks from homework and devices rather than working for hours without looking up.
• For yourself, set reminders to pause, look into the distance and, ideally, stand up and move around.

4. Follow your eye‑care professional’s advice

If you or your child already have myopia, your optometrist or ophthalmologist may suggest specific strategies to slow progression, such as special lenses, contact lenses or eye drops, alongside changes in daily habits. The new research supports the idea that combining treatment + better lighting + more time outdoors is likely to be more effective than relying on any single measure alone.

Key takeaway

The rise in nearsightedness is unlikely to be caused by just one factor, and the latest work does not claim to have all the answers. But it adds an important piece to the puzzle: the way we use our eyes indoors, and especially the light levels we choose while doing long bouts of near work, may matter more than we realised.

For now, some simple habits can stack the odds in your favour:

• Keep indoor lighting bright when you or your children read or use screens.
• Limit long, uninterrupted periods of close‑up work.
• Make outdoor daylight and distance‑viewing a daily priority.
• Get regular eye checks, particularly for children and teenagers.

These changes are easy to start today, cost very little, and align with the best current evidence on how modern visual habits may be shaping our eyesight.