The Eye Strain Break App is a simple, no frills, app that runs in the background of your watch to provide gentle reminders to give your eyes a break. Simply press the "Start Screen Time" button (If this is your first time using the app the first time you click the button it will ask for permission to send your notifications, press the button again after accepting notifications to start the reminders.) and the app will gently remind you to take a quick 20 second break and look at something 20 feet away.
No need to look at your watch to check how long you have been giving you eyes a break. At the end of the 20 second break you will be notified that the break is over.
When you are done with your work for the day simply press the "End Screen Time" button and the notifications until the next time you start working.