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