04 November 2022

Computer Eye Breaks

Welcome back. Have you ever heard of the 20-20-20 rule? I hadn’t. Apparently, taking a break of at least 20 seconds, every 20 minutes, to look at least 20 feet away has long been recommended as a way of easing eye strain when staring at a computer display. 

20-20-20 rule break reminder issued by software screen (Fig 2, www.contactlensjournal.com/article/S1367-0484(22)00199-0/fulltext).

I came upon the rule because a recent study confirmed that adopting the guideline does indeed help ease some symptoms of prolonged computer use. The study, conducted by a team of researchers affiliated with Spain’s University of Valencia, Slovakia’s Slovak University of Technology in Bratislava, and the UK’s Aston University, was the first to properly validate the rule.

Digital Eye Strain
Long sessions at the computer have been associated with eye and vision problems generally labeled “computer vision syndrome” or “digital eye strain.” It’s estimated that at least half of the people using computers in their regular work have some form of digital eye strain. The symptoms fall into two categories:

External symptoms, related to dry eye, include burning, irritation, dryness, tearing, foreign body sensation, sensitivity to bright lights and discomfort.

Internal symptoms, linked to accommodative or binocular vision stress, include eye strain, eye ache, headache, diplopia, blurred vision and difficulty in refocusing.

Study Elements
Participants The researchers enlisted 29 volunteers for the controlled clinical study. Inclusion criteria were digital eye strain determined by a standard questionnaire, best-corrected distance visual acuity at least 20/30 in both eyes, and computer use of a minimum of 4 hr/day, at least 5 days/week. (The average computer use reported by the participants was 7±2 hr/day, 6±1 days/week.)

Software A software application (https://www.blinkingmatters.com/) was modified to use each participant’s laptop computer webcam to assess user breaks, eye gaze and blinking and emit 20-20-20 rule reminders.

Eye blink and gaze detection software testing; the green square indicates the user is looking at the screen (Fig 1, www.contactlensjournal.com/article/S1367-0484(22)00199-0/fulltext).
Over the course of four visits one or two weeks apart, the researchers screened participants, installed the software onto participants’ laptops and instructed participants in the use of the 20-20-20 rule reminders. They also conducted two weeks of measurement sessions of about 45 minutes in the same laboratory, the same day of the week, from 9 to 11 a.m., under the same environmental conditions (temperature and humidity).

Digital eye strain, binocular vision and dry eye were assessed before and after two weeks of using the reminders and one week after discontinuing. These included symptom questionnaires, a full suite of binocular measurements (visual acuity, accommodative posture, stereopsis, fixation disparity, ocular alignment, accommodative facility, positive/negative vergences and near point of convergence), and dry eye sign assessments (tear meniscus height, conjunctival redness, blink rate and incomplete blinking, lipid layer thickness, non-invasive keratograph break-up time, corneal and conjunctival staining and lid wiper epitheliopathy).


With the 20-20-20 reminders operating, the participants spent less time on computer work. Although they took more breaks, the length of breaks decreased.

The only change to any binocular parameter after the management period was an increase in accommodative facility. Dry eye symptoms and digital eye strain decreased with the rule reminders, though that improvement was not maintained after the rule reminders ended. There were no changes on any ocular surface and tear film parameter with the rule reminders.

Data collected by study software before and after activation of 20-20-20 rule reminders with mean ± SD, min – max; min=minutes; ms=milliseconds, a-intra-average values. (Modified from Table 2, www.contactlensjournal.com/article/S1367-0484(22)00199-0/fulltext).
Wrap Up
The researchers concluded that the 20-20-20 rule is an effective strategy for reducing digital eye strain and dry eye symptoms; however two weeks was not long enough for significant improvement in binocular vision or dry eye signs.

I suspect that most of us learned long ago to look away and even get up from the computer, we just don’t do it enough. Maybe the catchy rule moniker will help.

Thanks for stopping by.

Study of testing the 20-20-20 rule in Contact Lens and Anterior Eye journal: www.contactlensjournal.com/article/S1367-0484(22)00199-0/fulltext
Computer vision syndrome questionnaire: www.sciencedirect.com/science/article/abs/pii/S0895435615000232
Dry eye questionnaire: okeyecare.com/wp-content/uploads/2020/12/OkotoksEyecare-DEQQuestionaire-Fillable-1.pdf
Articles on study and topic on EurekAlert! and American Optimetric Assoc. websites:

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