trifocal lens

[trī-fōkəl, trīfō′-]
n.
  1. A lens having one section that corrects for distant vision, a second section that corrects for intermediate vision, and a third that corrects for near vision.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.