Since the index of refraction of the tear layer and the cornea are very similar, you now have a regular optical surface in place of an irregular one If the curvature of a contact lens is not the same as the cornea (as may be necessary with some individuals to obtain a comfortable fit), the tear layer between the contact and cornea acts as a lensA multifocal lens having a center optical zone for creating a first focal point within 2° of the optical axis and a peripheral optical zone located adjacent the center optical zone for creating a second focal point from 2° to 10° of the optical axis, the peripheral optical zone having a correction of at least 2 diopters more than the center optical zoneThe aim of the study was to investigate the prevalence of induced prismatic effects due to poorly fitting spectacle frames A sample of 100 spectacle wearing subjects was selected as participants Document If optical and opticians are coded as 76 and 87 respectively glasses will be ...