Optical instrument testing accommodation and convergence - has two eyepieces focussing separately on test image via semi-transparent mirror and pivoting mirror

摘要

The instrument is used in the assessment of the convergence and accommodation of the patient's eyes. It comprises a disc (4) carrying the test images and two eyepieces each forming a separate image. A mirror (20) is mounted to pivot about an axis parallel to its plane between two distinct positions where it serves each eyepiece exclusively. A semi-transparent mirror (22) is positioned at 45 deg. to the optical axis of the objective and the eyepieces are positioned on the opposite side of the mirror to the objective.