What is a good set of notes to study human's eye mathematically?
Mathematical models of the human eye


Fluid mechanics


Mathematics of Eye


Physics of blinking
Thin layer approximation (lubrication theory)
Aqueous flow in eye chambers
Tonometry


Those two links provide quite a sufficient description of how to mathematically describe/analyze the human eye. It seems that you need to be fairly familiar with (at least) differential, integral and vector calculus in order to competently study the eye, mathematically. If you can get through (and understand) the fluid mechanics then you'll be well off. 

And as for practice problems, aside from the examples in those links, I'm not sure you'll so easily be able to find sets of mathematical practice problems that specifically describe the eye. Or at least, I wasn't able to find any such  repository.