3.1 Radiation in medicine 3.2 How eyes work Prezi - How eyes work Video - TED Education - How eyes work Video - Billy Nye, on the eye Video - Human eye in extreme detail Prezi - Sight problems Video - Anatomy of the eye Video - How laser eye surgery works Video - Laser eye surgery Revision Video - Reflection and refraction 3.7 - 3.9 Total internal reflection and the Critical Angle |