eyeholes

/AY1 HH OW0 L Z/
noun
  1. 1

    The hole to which the viewer places his or her eye in a device such as a telescope.

  2. 2

    The hole in a helmet, skull, etc. corresponding to the position of the eye.

Source: https://en.wiktionary.org/wiki/eyehole, https://en.wiktionary.org/wiki/eyeholes