The non spherical annular area has a progressive reduction from maximum addition to zero addition, which enables {HEAD ~ vision} from {TAIL ~ reading} to intermediate and distance vision 
The non spherical annular area has a progressive reduction from maximum addition to zero addition , which enables { HEAD ~ vision } from { TAIL ~ reading } to intermediate and distance vision
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH