Progressive Glasses, also called progressive addition lenses (PAL), progressive power lenses, graduated lenses, no-line bifocals, and varifocal lenses, are used in to correct and other disorders. They are characterised by a gradient increasing, added to the progressive glasses wearer’s correction for the other. The gradient starts at a minimum, no addition power, at the top of the glassses ,and reaches a maximum addition power, at the bottom of the lens. The length of the progressive power gradient on the lens surface is usually between 15 and 20 mm with a final addition power between 1.00 to 2.50 for most progressive glasses wearers. The addition value prescribed depends on the level of of the patient and is closely related to age.