Présences du littéraire dans l’espace public canadien

When the eye can no longer focus sharply on near objects, an optical lens is required to assist in reading and near work. Three basic lens designs can provide this assistance. Bifocal lenses are convenient, as they offer the wearer two fields of correction, distance, and near. Trifocals go a step further, with an additional zone for intermediate, arms length vision. The third and most recent optical lens design is the progressive addition lens. Progressive addition lenses are a technically advanced design which allows continuous vision from infinity to near. Because of the absence of lines, the visual path is smooth and uninterrupted. In addition to improved visual comfort, esthetic appearance is enhanced. By trying the various styles, individuals can determine which types of design can best suit their needs.