APPARATUS AND METHOD FOR DETERMINING VISUAL ACUITY OF A SUBJECT

摘要

An apparatus (2) for providing a focussed visual state of a subject is disclosed. The apparatus comprises a fast focus switchable lens (6) for alternately focusing an image at (i) a first position at a first distance behind a second position and at (ii) a third position at a second distance in front of the second position, wherein the first distance is substantially equal to the second distance. A refraction correction lens system (12) adjusts the second position.