Screen time and eye strain: what actually helps

Eye strain from screen use is one of the most common things patients mention at their appointments. The symptoms are real: tired eyes, headaches by mid-afternoon, difficulty focusing after a long day at a computer. The causes are also real, though they are not always what the marketing around blue light glasses would suggest. This article covers what is actually happening and what tends to help.

What causes screen-related eye strain ¶

The primary cause of eye strain from screen use is sustained near-focus effort. The focusing muscle inside the eye, the ciliary muscle, contracts to focus at close distances and relaxes for distance vision. Holding that contraction for hours at a time causes fatigue, in the same way that holding any muscle in a fixed position causes fatigue.

Reduced blink rate is a secondary factor. People blink roughly 15 times per minute in normal conditions and around 5 times per minute when concentrating on a screen. Fewer blinks mean the tear film is refreshed less often, which contributes to dryness and discomfort.

What blue light glasses do and do not do ¶

Blue light filtering lenses reduce the amount of short-wavelength light reaching the eye. The theory behind them is that blue light from screens disrupts sleep and causes retinal damage. The evidence for both claims is weaker than the marketing suggests.

A 2021 Cochrane review found no clinically meaningful benefit from blue light filtering lenses for eye strain or sleep quality. The College of Optometrists in the UK does not recommend them for this purpose. We do not sell them on the basis of eye strain claims, though we will fit them if a patient specifically requests them.

What does help is the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds. This gives the ciliary muscle a brief rest and prompts a blink. It costs nothing and the evidence for it is reasonable.

When a lens change might help ¶

For patients in their late 30s and 40s who are beginning to notice that near focus takes more effort than it used to, a small near-vision boost in the lower portion of a single-vision lens can reduce the strain significantly. The Hoya Sync III lenses we fit at Cedar Vision Works are designed for this purpose.

If your prescription has not been checked in the past two years and you are experiencing regular eye strain, an up-to-date examination is the most useful starting point.

Eye strain from screens is manageable in most cases with a combination of the right prescription, good working habits, and, where appropriate, a lens design suited to near work. If it has been a while since your last test, that is probably the right place to start.