Zeiss BlueGuard lenses at Direct Vision Opticians Birmingham

Do blue light glasses work? An optometrist's honest answer

July 3, 2025

Blue light lenses are one of the things we're asked about most. Here's the honest answer: there's no good evidence that blue light from phones, tablets and computers damages your eyes, or that blue light filtering lenses prevent eye strain. Some people still like them, and that's fine, but it's worth knowing what actually makes eyes tired at a screen.

Is blue light from screens harmful?

Screens give off far less blue light than daylight. Current evidence doesn't show that the amount from digital devices harms the retina. The College of Optometrists, the professional body for optometrists in the UK, does not recommend blue light filtering lenses to protect eyes from screens.

So why do my eyes feel tired after screen time?

Digital eye strain is real, but it's mostly caused by how we use screens rather than the light itself:

We blink less when concentrating, so eyes dry out and feel sore
Focusing up close for hours tires the focusing muscles
An out-of-date prescription, or a small uncorrected one, makes your eyes work harder
Screen position and glare from windows or overhead lights

What actually helps

The 20-20-20 rule: every 20 minutes, look at something about 20 feet away for 20 seconds
Blink fully and often, and keep the air from drying out
Set your screen an arm's length away and slightly below eye level
Have an eye test to check your prescription is right for screen distance
Consider screen or occupational lenses if you spend long days at a desk. These are designed for computer and desk distances and can be much more comfortable than standard single vision or varifocal lenses. Ask about Zeiss occupational lenses on our Zeiss lenses page.

What about sleep?

Bright screens late at night can make it harder to wind down, but the evidence that blue light filtering glasses improve sleep is mixed. Turning screens down or off before bed is the simplest step.

Should I get blue light lenses?

If you like the idea, they're safe to wear, and coatings such as Zeiss BlueGuard also include anti-reflective properties that cut reflections on the lens. Just choose them as a preference, not as treatment for an eye problem. If your eyes are uncomfortable at a screen, the first step is an eye test.