Because of the screen size, iPad can display the topmost  (Snellen Fraction 6/60, Decimal 0.1, or LogMar 1.0) optotypes at 6 meters' distance. Eye charts have been tested in varous iPad models from iPad 3 to iPad 2017.

iPad Pro Snellen Chart

iPad Pro ETDRS Chart

iPad Pro

iPad Mini 4

iPad Mini 4 - About

iPad 8

iPad 8 Scores

iPad Air 2019

iPad Air 4

iPad Mini 2019

iPad Pro 11 2020

iPad Pro 2020