The 20-20-20 rule is designed to be an easy to remember caution about doing too much near work and to give your eyes a break from eye strain regularly. This rule is supported by conventional optometry and is a start towards the EM method.
- Every 20 minutes
- Look at something 20 feet away (6 meters)
- For at least 20 Seconds
Endmyopia recommends even more breaks.
- Every 20 minutes, take a 5 minute break.
- Every 3 hours, take the longest break you can (half hour to hour) (3 hour rule)
- Take your break outside. 
- As you develop Strain Awareness you can customize your break schedule to your needs.
One more thing
The most commonly asked question about the 20-20-20 rule is: "Do I need to switch back to [normalized] every time I shift focus, for a break?"
The answer is: whatever you wish. However, it would make your life easier if you kept the focal plane you are already using, be it differentials or nothing depending on where you are in your journey, for breaks under 5 minutes. If you are taking a much recommended longer break; this is a good time to switch to normalized, in order to ensure you are not trading close up strain for excessive blur strain.
Reverse 20-20-20 rule
Which glasses should you wear if you don't want to change your glasses all the time?
At least two people in the Discord chat have the following personal rule: If you will be in blur for more than 20 minutes, change to your other pair of glasses.
Do you need the 20-20-20 rule?
The 202020202002020202 rule isn’t ours / mine / endmyopia. I think it’s kind of pointless but I :zipper_mouth_face: when people bring it up since … :man_shrugging:— Jake Steiner
20202020202020202020000 rule is really just mainstream articles filtering into here. When you get distance vision your ciliary unlocks anyway. Whether ciliary spasm shuts off axial gains is debatable, light rays still converge in front of eye in theory. Try without 202020 rule and see if you still make the gains.— NottNott
It was never an Endmyopia rule, it’s a mainstream optometrists / work ergonomics recommendation.
Jake generally recommends longer breaks. He says that a break needs to be at least 10-15 minutes to be really effective. He also recommends to have 1 hour break after every 3 hours of close-up.
But these are not strict rules. Generally what matters if you get ciliary spasm during your close-up or not. The best way to make sure is to check a Snellen chart or some “landmark” before you do close-up. You should be able to maintain the same acuity during close-up. If you detect blur on the same Snellen chart / landmark, then you should take a break.
Edit: to avoid misunderstandings, the 20/20/20 doesn’t do any harm, but on it’s own is not enough to prevent or eliminate ciliary spasm.— halmadavid
- "American Optometric Association 20-20-20 rule poster" (PDF). American Optometric Association. 2020-05-30. Retrieved 2020-05-30.
- Nall, Rachel (2020-05-30). "20-20-20 rule: How to prevent eye strain". www.medicalnewstoday.com. Retrieved 2020-05-30.
- Steiner, Jake. "Eye Strain Awareness: Prevent Pseudo Myopia - Endmyopia". endmyopia.org. Retrieved 2020-06-01.
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