The eye doctor business has taken to heart, The late Herman Snellen's acuity chart. Working down line by line from that Capital E, The doctor could tell just how well we could see. And though he ...

A perfect 20/20 score on an eye chart test doesn't mean you have perfect vision: Visual acuity, along with color, contrast, and depth perception, are all important parts of healthy eyesight.

"Color-changing contact lens could enhance monitoring of eye disease treatments." ScienceDaily. ScienceDaily, 10 October 2018. <www.sciencedaily.com / releases / 2018 / 10 / 181010124932.htm>.