Eye astigmatic refraction evaluation instrument - has flat tilting mirror imposing sweeping action on light ray bundle

摘要

The hand instrument evaluates the objective astigmatic refraction in the eye of a patient using the skiascopy method. A flat mirror is turned about an axis, to impose on a bundle of light rays a sweeping action of 20 to 30 degrees minimum in the plane perpendicular to this axis. The latter can be parallel to the mirror and orthogonal to the optical axis of the bundle of rays. Tilting of the mirror can be of lever or pushbutton connected to its bracket by a linkage and there can be a return spring between the mirror bracket and the instrument body, restoring the mechanism to a stable position.