A lens of glass worn in front of the eye to assist vision; -- usually used in the plural, referring to a pair of lenses fixed together in a frame, and worn resting on the bridge of the nose, to improve the vision. A single eyeglass in a frame is called a monocle.

A glass eyecup. See Eyecup.

lens for correcting defective vision in one eye; held in place by facial muscles

Eyepiece of a telescope, microscope, etc.

The retina.