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