Ocular

Part of speech: noun (n.)

The eyepiece of an optical instrument, as of a telescope or microscope.

Part of speech: adjective (a.)

1. Depending on, or perceived by, the eye; received by actual sight; personally seeing or having seen; as, ocular proof. Shak. Thomas was an ocular witness of Christ's death. South.

2. Of or pertaining to the eye; optic.