Blue-light glasses are said to reduce eye strain when using computers, improve your sleep and protect your eye health. You can buy them yourself or your optometrist can prescribe them.

But do they work? Or could they do you harm?

We reviewed the evidence. Here's what we found.

What are they?

Blue-light glasses, blue light-filtering lenses or blue-blocking lenses are different terms used to describe lenses that reduce the amount of short-wavelength visible (blue) light reaching the eyes.

Most of these lenses prescribed by an optometrist decrease blue light transmission by 10-25%. Standard (clear) lenses do not filter blue light.

A wide variety of lens products are available. A filter can be added to prescription or non-prescription lenses. They are widely marketed and are becoming increasingly popular.

There's often an added cost, which depends on the specific product. So, is the extra expense worth it?