Doing research of my own on the subject. Just google "20/20/20/ rule". I just did, and found the following article. An eye care professional tracked it down and

Doing research of my own on the subject. Just google "20/20/20/ rule". I just did, and found the following article. An eye care professional tracked it down and attributed to... another eye care professional. https://www.optometrytimes.com/view/deconstructing-20-20-20-rule-digital-eye-strain https://www.optometrytimes.com/view/deconstructing-20-20-20-...