eyehole

noun3

1. •
   The hole to which the viewer places his or her eye in a device such as a telescope.
2. •
   The hole in a mask, helmet, or costume corresponding to the position of the eye, allowing the eye to look through it.

   • Eyeholes in a paper bag Greatest lay I ever had — 1997
3. •
   The hole in the face where the eye resides.