Genetics are a big part of it, like you would expect, but its a bit more nuanced than what we learned in high school biology.

Damage to the light-detecting cells of the retina is irreversible and causes blindness. In November 12 online Nature Neuroscience Masatoshi Haruta and colleagues from Kyoto University, Japan show that ...

The eye has three coats (sclera–cornea, uvea, and retina) and two humors (aqueous and vitreous). The conjunctiva covers the visible portion of the sclera (bulbar conjunctiva) and lines the eyelids ...