If you often feel your eyes straining from staring at a digital screen for too long, try this: For every 20 minutes of screentime, take one 20-second break, during which you look at an object 20 feet away. This is the 20-20-20 rule.
Explaining why a break is necessary during extensive periods of screen time, Dr Anita Sethi, Director of Ophthalmology at Fortis Memorial Research Institute Gurugram says the tear films in your eyes can evaporate and dry your eyes up.
“Basically, you have to look away from the screen at some far-off objects so that your eye muscles get a chance to relax,” she says.
Eye strain is an avoidable consequence even for people who work at computer screens for over seven hours a day. While the 20-20-20 rule can help Computer Vision Syndrome or CVS, by itself, the formula may not be enough.
“It could easily have been a 40-40-40 rule. The only reason why it’s the 20-20-20 rule is because it’s easier to remember,” adds Dr Sethi.
What is CVS?
CVS is also known as digital eye strain and is characterised by visual fatigue, blurred vision and even diplopia (double vision). Its other symptoms include dry eyes and headaches. (Source)
Dr Piyush Tewari, Ophthalmologist at Tewari Eye Centre in Delhi, likens your eyes to a camera that can focus on objects both close and far. “For someone who is working on a computer for more than eight hours at a stretch, the eye muscles tend to stay constricted, giving them eye strain,” he says.
At least 60 million people suffer from CVS across the world, according to surveys. Symptoms of CVS fall under two categories – Accommodative or binocular vision stress and external symptoms linked to dry eye.
“If you are accommodating your eyes, which means constricting your eye muscles to see closer objects, then it can cause eye strain. That’s why the 20-20-20 rule is advised as a guideline,” says Dr R. Kim, Chief Medical Officer, Aravind Eye Hospital, Madurai.
Follow screen protocol
If you are someone who use digital screens for extended periods of time, here are a few useful tips to relax your eyes and prevent CVS.
- Use screens with high refresh rates – At least 75 Hz or higher, suggests Dr. Tewari.
Lower refresh rates of 30-50 Hz, seen in older monitors, can cause fatigue and headaches.
- Use a bigger font size for text
- Blink frequently
- Maintain the right posture while using a digital screen – keep a distance of one-and-a-half arms from your workstation.
- Do not work in dimly lit environments – changing the lighting in the room can help to reduce eye strain. (Source)
- Increase environmental moisture levels to avoid dry eyes – Your eyes can dry out in low-humidity environments. One study shows that adding a humidifier may help.
- Reduce levels of blue light radiation emitted from displays – Using free apps like f.lux and MacOS’s night shift mode can help in this.
Blink rate and dry eyes
“While using computer screens for extended periods of time, an individual should look at distant objects and blink frequently to prevent symptoms of dry eye,” says Dr Kim.
When we stare at computer screens, we tend to blink less frequently than we ought to, increasing stress on the eyes. Studies have shown that the blink rate is significantly reduced for people who work with computer screens. It was found that a mean rate of 18 blinks per minute before using a computer screen got reduced to 3.6 blinks a minute after screen use.
Regular blinking helps to maintain a healthy ocular surface. “The focus should be on giving your eyes relaxation, and redistribution of the tear film,” says Dr Tewari. “Blinking does the same.”
CVS affects youngsters as much as it does adults. Students who actively use digital screens for more than two hours a day have been found to develop its symptoms. A study led by researcher Bambang Zulkarnian of Airlangga University in Indonesia established that introducing artificial tears (eye drops) and employing the 20-20-20 rule can help combat this.
However, for preserving your eye health, the 20-20-20 rule by itself may not be enough. Both experts and studies alike suggest that you should complement it by practising screen etiquette – blinking frequently, working in a well-lit environment and if necessary, using eye drops.