Light enters the eye by first passing through our cornea, a protective layer over our eyes. Then, it will pass by the iris and enter the pupil. Through the pupil, it goes through a lens.
Now a lens refracts light, and we think of glass lens on cameras or glasses on first thought, huh? We have lens in our eyes, light does the same thing here, though, it refracts. It then reflects off of the retina and to the optic nerve. From there, it enters the brain to be processed.
And that's how light travels through your eye to help you see.