eyeglass

noun5

1. •
   An artificial lens, especially one of a pair.
2. •
   A monocle.
3. •
   [before a noun] Attributive form of eyeglasses.
4. •
   An eyepiece.
5. •
   (no longer used) The lens of the eye.

   • Ha' not you seen, Camillo? / (But that's past doubt; you have, or your eye-glass / Is thicker than a cuckold's horn) — 1610