Numerous texts I've read on eye anatomy/physiology claim that it is the cornea that is responsible for most of the eye's refractive power. Can someone perhaps explain to me how this could be the case? I would have thought that, considering that the tangents to the points of entry and exit of a light ray passing through the cornea are approximately parallel, the overall refractive power of the cornea would be very little. I would have thought, therefore, that it is the aqueous humour that is responsible for most of the eye's refractive power. Am I missing something? Can anyone help me? Is it conceivable that the texts I have been reading are actually wrong? P.S. A diagram always helps. Please look at the one http://www.samluc.com/science/vision/images/cornea.gif. It is in the manner depicted in this diagram that I believe a ray of light would behave when passing through the cornea - assuming that the mediums on either side of the cornea had the same refractive index, as when viewing an object underwater for example, as water and the aqueous humour have approx. the same refractive index.