Why do screens make your eyes dry?

Why screens dry your eyes

Your tear film starts to thin and evaporate between blinks, and each blink renews it. The 2023 TFOS report on the digital environment names reduced blink rate and completeness as the main ways screen work makes the eye’s surface worse, along with an uncorrected or partly corrected prescription, the mental demand of the task, and the position, size, brightness and glare of the screen.

Where you look matters too. Tsubota and Nakamori measured the exposed surface of the eye at about 1.2 square centimetres looking down, 2.2 looking ahead and 3.0 looking up, and tear evaporation rose with it, to more than twice as much looking ahead as looking down. A screen at or above eye level keeps the eyes wider open than a book in your lap.

The room adds to it. The American Academy of Ophthalmology notes that sitting near a vent can quickly dry out your eyes, and suggests a humidifier for dry, warm rooms.

What may help

Blinking: a cue to blink, with people told to blink when they saw it, raised blink rate and eased symptoms more than a placebo in Nosch and colleagues’ 2015 study. A full blink, with the lids meeting, matters as well as how often.

Breaks: in a 2023 trial, reminders to follow the 20-20-20 rule eased symptoms over two weeks, and the benefit was gone a week after they stopped (Talens-Estarelles, 2023).

Screen position: the American Optometric Association suggests the centre of the screen sit 15 to 20 degrees below eye level and 20 to 28 inches (about 50 to 70 cm) from your eyes. The AAO suggests about an arm’s length, with your gaze slightly downward.

Air: move out of the path of fans, heaters and air vents, and in a dry, warm room a humidifier may help (AAO). The TFOS report lists humidifiers among promising approaches that need more study.

Your prescription: TFOS advises a full correction for the distances you work at, so an eye test that takes your screen distance into account is worth having.

What doesn’t need buying

Blue-light glasses. A 2023 Cochrane review of 17 trials found they may make no difference to eye strain in the short term, the AAO doesn’t recommend them, and the College of Optometrists says the evidence doesn’t support them for the general population.

Supplements are less clear cut. In the DREAM trial, 535 people with moderate to severe dry eye took 3,000 mg of fish oil or an olive oil placebo daily for a year, and the fish oil did no better. The TFOS report still lists supplements as promising, so the evidence is mixed. Ask an optometrist or pharmacist before spending on them, or on eye drops: the AAO suggests artificial tears when eyes feel dry, and TFOS says larger trials are needed to show which help with screen use.

When to see someone

See an optometrist or eye doctor if your eyes stay dry or sore after you’ve changed how you work, or if they are often red, blurry or watery, become sensitive to light, or hurt (AAO). Get any change in your vision checked. Dry eyes have causes besides screens, and an eye examination can find them and check whether your glasses suit the distance you work at.