Phone in the Dark: How Bad?

Smartphones and tablets are everywhere. Adults and kids use them, and lots of people scroll before bed with the lights off.

Online claims about eye damage from this vary—some make sense, others overhype. As an eye doctor, here’s the scoop.

Eye Surface Damage

The biggest issue is with your tear film (the moisture layer) and cornea. Normally, you blink about 20 times a minute, but less when staring at screens. In the dark, the bright screen makes it worse: tears dry up, and the tear film breaks down. Bad cases even get tiny scratches on the cornea.

This causes dry eye—symptoms like tiredness, gritty feelings, burning, redness, or pain.

Glaucoma Risk? Possible.

Rumors say dim light keeps pupils wide, blocking fluid and causing glaucoma (even blindness). Could that happen?

Maybe. Eye pressure stays balanced with fluid that circulates. In dim light, focusing close tenses eye muscles—lens bulges, pupils widen—and pressure can rise. Over time, this might permanently damage the optic nerve.

People with small eyes or shallow eye chambers are more at risk. For them, long phone use in the dark could trigger acute glaucoma, badly harming the nerve.

Macular Damage? Not Proven.

The macula is where sharpest vision happens. Damage here causes blurriness or distortion. Most issues are age-related, but young people sometimes get problems linked to stress or fatigue (cause unclear).

No studies prove phones harm the macula. Some doctors see younger cases, but no research ties phone use in the dark to it.

Still: A bright screen in darkness, stared at up close, floods eyes with high-energy light. Could long-term use hurt the macula? Maybe—but we don’t know for sure.

Bottom Line

Using your phone in the dark is harmful: it damages the eye surface, raises glaucoma risk, and might harm the macula.

As an eye doctor, skip long screen time in the dark. Protect your eyes.