Twenttty reminds you to give your eyes a break. It notifies you about taking a 20 second break every 20 minutes of your screen activity and asks you to look at something far away (at least 20 feet) to relax eye muscles.
Twenttty stays out of your way and doesn’t break your workflow. Once it prompts a system notification, it’s your turn to decide what to do. Look at something far away or close your eyes, take a deep breath, calm your thoughts and wait for the break end chime to play. Or simply ignore it. You’ll get another reminder in 20 minutes anyway.