Future Optometrists

  OPTICAL PROPERTIES OF OPHTHALMIC LENS      When a beam of light falls on lens surface, some light passes through lens, some of the light is reflected from lens surface and some of light is absorbed by lens material.      The measure of the proportion of light reflected from surface is called reflectance.      The measure of the proportion of light absorbed is the absorption.      The measure of the proportion of light transmitted is the transmittance.      Each one is expressed as a fraction of the total quantity of light in the beam.        If the intensity of the beam of light is represented by number 1, reflectance by R, absorption by A and the transmittance by T,  the intensity of light may be expressed as follows: R + A + T = 1      The aim of Ophthalmic lenses is to restore clear vision to ametropic eye by placing a corrective lens between the viewed object ...