How to Understand and Draw Eyes
From Xananax:
I noticed a lot of people don't understand how eyes work. This quick exposition attempts to give the basics of how to draw an eye. The knowledge should be widely applicable, whether you're cartooning, drawing realistic characters, or even modelling in 3D
As several commentators pointed out, a few caveats as you're going through this:
1 - All contrasts are exaggerated. This is *not* a tutorial to learn how to draw. You shouldn't be copying this stuff. This is a tutorial to *explain*. Refer to other, more accurate references for when you get to drawing.
2 - At some point, I argue that the iris is curved inwards. It is not, actually, biologically true. It appears inwards due to the cornea's curve. But for us artists, as well as for 3D modelers, how it appears is what matters
Find How to Understand Eyes from Imgur User Xananax here.