However, we obviously don’t normally look at eyes this way—without eyelids and independent of the face. Why, then, should we consider the eye’s shape?
Well, I like to think about the relationship between eyeballs and eyelids much like fabric on an object—eyelids wrap around the eye. They are not flat or straight on the eye. Instead, they’re rounded, going around the spherical shape of the eye. This premise is illustrated in blue, below.