Types Of Glasses Lenses

Types of glasses Lenses Glasses come in many types. They can be classified by their primary function, but also appear in com- binations such as prescription sunglasses or safety glasses which enhanced magnification. Single vision lenses correct for only one dis- tance. If they correct for far distance, the person must accommodate to see clearly up close. If the person cannot accommodate, they may need a separate pair of single vision glasses for near distances. Single vision Corrective lenses are used to correct refrac- tive errors by bending the light entering the eye in order to alleviate the effects of con- ditions such as nearsightedness , farsighted- Corrective or astigmatism. ness With a bifocal, the upper part of the lens is generally used for distance vision, while the lower segment is used for near vision. The area of the lens that caters to near vision is called the add segment. Bifocal Trifocal lenses are similar to bifocals, except that the two focal areas are separated by a third in the middle. This segment corrects the wearer's vision for intermediate distances roughly at arms' length, e.g. computer distance Trifocal Progressive addition or varifocal lenses provide a smooth transition from distance correction to near correction, eliminating Progressive segment lines and allowing clear vision at all distances Oakes Opticians Designed & Issued In Public Interest http://www.oakesopticians.co.uk/