It’s similar to a magnifying glass focusing a beam of sunlight on one specific spot. More people wanted smoother transitions between these visual areas, especially if they have more than two powers in their glasses or contact lenses. Vision Correction Physics They float on the surface of the cornea. How do contact lenses work physics . Bifocal contact lenses sometimes work the same way. To do all that, the eye has a lens between the retina and the pupil (the peep hole in the center of your eye that allows light into the back of the eye) and a transparent covering, or cornea (the front window). Earlier contact lenses were made of glass, and were scleral lenses. A lens works by refraction: The physics and biology of vision. In myopia defects, the conversion power is slight before the retina, so the light rays do not fall on your retina, and the same convergence power is carried forward a little by using minus lenses. When light is refracted it changes direction due ...