The EYE: Refraction of light by the eye

Refraction - basic notes

You need to know how to calculate the refraction that occurs at media interfaces and to know which way the refraction will go (towards or away from the normal).

The strongest refraction occurs when light first enters the eye at the air/cornea interface because the difference in refractive index of the two media is the greatest.

The presence of the aqueous and vitreous humours reduces the amount of refraction taking place at the lens as their refractive indicese are closer in value. The main purpose of the lens is to finely adjust the overall focus of the eye, ie to permit accommodation.