Human eyes can’t decipher individual pixels from far away—this video shows why. A version of this story appears in the October 2018 issue of National Geographic magazine. Short for “picture ...

If I use 1 arcminute instead, the scale factor is smaller, about 3438. So let’s convert that to inches to see how small a pixel the human eye can resolve at a distance of one foot: 12 inches / 3438 = ...

Chapter 1, "The formation of the human eye," focuses on overall eye embryology ... for those of us over 50 of the way accommodation, resolution and other functions change over a lifetime.