Screen Time, Eye Strain and What Helps

Several factors combine, and most of them are fixable.

Blinking deserves special attention. The AAO notes that people normally blink about 15 times a minute, but only about 5 to 7 times a minute while using computers and other digital devices. The digital eye strain review adds that incomplete blinks, where the upper eyelid does not cover the whole cornea, may be even more relevant to dry eye than the reduced blink rate itself.

Uncorrected vision is the most overlooked factor. The AOA says that in most cases symptoms occur because the visual demands of the task exceed the visual abilities of the individual to perform it comfortably, and that glasses prescribed for distance or reading may not suit the intermediate distance of a computer screen.

Small changes to the workstation remove much of the strain. The table below combines guidance from the AOA and the AAO.

Sources: AOA on computer vision syndrome and AAO on computers, digital devices and eye strain.

The screen height advice overlaps with general ergonomics guidance, which places the top of the monitor at or slightly below eye level. A slight downward gaze also exposes less of the eye's surface, which can help with dryness.

For laptops, the conflict between screen height and keyboard height is the main problem. A stand plus an external keyboard solves both the eye and the neck side.

With two monitors, put the one you use most directly in front of you and the second beside it at the same height and distance, angled toward you. If you use both equally, center the seam between them. Keeping both screens at a similar distance and brightness means the eyes do not have to refocus or adapt every time you glance from one to the other.

Phones deserve the same thought. Reading long documents on a small screen held close forces near focus for long periods. Move long reading to a larger screen at a comfortable distance, or to paper, when you can.

The best-known advice is the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds. The AOA recommends it, and it adds a longer rest: rest the eyes for 15 minutes after two hours of continuous computer use.

The research on the exact rule is mixed.

• A trial that found no effect. A study of 30 young adults doing a 40-minute reading task on a tablet compared 20-second breaks every 5, 10, 20 or 40 minutes. Symptoms rose in all conditions, and scheduled breaks had no significant effect on symptoms, reading speed or accuracy. The authors note there is relatively little peer-reviewed evidence for the rule.
• A trial that found a benefit. A study of 29 symptomatic computer users used software reminders based on the 20-20-20 rule for two weeks. People took more breaks, and digital eye strain and dry eye symptoms decreased with the reminders, but the improvement was not maintained a week after the reminders stopped, and dry eye signs did not change.
• A review of the literature. An article in Modern Optometry concludes that the relevant data on the 20/20/20 rule are unclear.

A reasonable reading is that breaks help some people, especially when a reminder makes them happen, and that the precise numbers matter less than the habit. Practical options:

• Use a reminder app or timer if you tend to lose track of time.
• Look out a window or across the room during calls where you mostly listen.
• Take longer screen-free breaks between focus blocks, such as a walk or a phone call away from the desk.
• Alternate tasks, as the AOA suggests, with work that does not require close focus.

Blue-light filtering glasses are widely marketed for eye strain, sleep and eye protection. The strongest evidence comes from a Cochrane review of 17 randomized controlled trials.

Cochrane's summary states that spectacles marketed to filter out blue light probably make no difference to eye strain caused by computer use or to sleep quality. The review also found no evidence that these lenses protect the retina. The senior author said the findings do not support prescribing these lenses to the general population, while noting that the certainty of the evidence is limited by short follow-up and small studies.

The full review in the Cochrane Database of Systematic Reviews reports that there may be no difference in subjective visual fatigue scores between blue-light filtering and non-filtering lenses at less than one week of follow-up, and it rates that evidence as low certainty. Ophthalmology Times, reporting on the review, summarized the outcomes as inconclusive for the main marketing claims.

Some professional sources still recommend tints and coatings, and the AOA page mentions them. Given the Cochrane findings, a better first investment is an eye exam and, if needed, glasses prescribed for screen distance.

Computer glasses are a different thing. The AAO describes prescription glasses that focus the eyes at intermediate screen distance, which can reduce strain for people who work on a computer for many hours. These correct focus, not light color.

Because blinking drops at the screen, dryness is one of the most common complaints. The AAO suggests several steps:

• Make a conscious effort to blink often, even with a reminder note on the screen.
• Use artificial tears when the eyes feel dry.
• Use a humidifier in a dry, warm room.

Contact lens wearers are more prone to ongoing dryness at screens. The AAO advises giving your eyes a break by wearing glasses instead, not sleeping in contact lenses even if they are labeled extended wear, and following good lens cleaning practices.

The AOA recommends that computer users get a thorough eye exam every year, and says even a mild glasses prescription may be needed to reduce vision stress on the job. It suggests telling the examiner about your job tasks and measuring the distance to your screens, so the prescription can match them.

The AAO lists signs that need prompt attention: eyes that are consistently red, blurry or watery, sensitive to light or painful are a reason to see an ophthalmologist. Symptoms that persist after you stop using screens also deserve an exam, since the AOA notes some people keep experiencing blurred distance vision.