The 20-20-2-20 rule

The American Academy of Ophthalmology explains that looking at digital devices does not necessarily damage your eyesight. But it may cause strain and unpleasant symptoms. On average, our eyes blink 15 times per minute. Looking at a screen reduces this number and makes our eyes tired and dry. 

Other related symptoms of eye strain include dry eyes, watery eyes, blurred vision, doubled vision, headaches, soreness in the neck, shoulders or back, sensitivity to light, trouble concentrating, difficulty keeping eyes open. 

The 20-20-2-20 will help you and your students or children relax their eyes while working and studying using digital devices. 

This rule is:

20 - 20: after staring at the screen for 20 minutes, you should look further away and count slowly to 20. Why 20? Because our eyes need at least 20 seconds to relax completely. We can drink some water during counting because it helps keep our body hydrated, including our eyes. Green tea is also a very beneficial drink for the eyes as it contains the antioxidants called catechins that may help our eyes produce tears for better lubrication. 

2-20: after working and learning for 2 hours on digital devices, we should take 15 to 20 minutes break to move around and do some physical exercises. 

Remember this drill every time you sit down at your work/study station:

1. The computer screen should be one arm length away from you. Move the screen, so you look slightly downward at the screen. 
2. Put your device in the position without the screen’s glare. 
3. Clean the screen. Dirty screens will make your eyes strain even more
4. Dim the light of the screen or adjust the light in the room to reduce contrast 
5. Remember to blink your eyes more often (use eye drops if they are dry)
6. Remember and apply the 20-20-2-20 rule

For teachers & parents, you may: 

1. Use the countdown timer on the screen or slide show or a watch to help students be aware of the time and know when to relax their eyes, take a break and move around. 
2. Save the links of some fun physical exercises from Youtube so children can practise during break time. 
3. Instruct the children to apply the 20-20-2-20 rule based on their age and remind them what they should pay attention to every time they sit at the workstation in front of a digital device.

External sources:

https://www.healthline.com/health/eye-health/20-20-20-rule#prevention

Count down timer & how to add count down timer to your slides

• https://www.online-stopwatch.com/timer/20minutes/
• https://www.youtube.com/watch?v=9cNFAEeFYMk
• https://www.youtube.com/watch?v=puHhdyzhUkM
• https://www.youtube.com/watch?v=Q7abDF9uCNU

Physical exercise video from the Viet Nam Health Program - Ministry of Health