Optician's instrument for measuring head position - has telescopic lens and rotatable inverting prism or mirror system to measure rotation angle relative to housing

摘要

The optician's instrument for measuring head position consists of a housing (11) contg. a rotating inverting prism (1) or mirror system, (15, 18) for measuring the angle of rotation of the latter relative to the housing, and a telescopic lens (3, 4, 5) and a reticule (5) at the focal point of its lens (4). Pref. there are two rotatable inverting prisms or mirror systems in binocular arrangement. A marking defines the objective vertical after adjustment of the instrument by spirit levels, to increase the precision of measurement. The instrument is used in cases of nystagmus and spontaneous and induced changes in head position in the event of disturbances of the eye muscles which are in a position to roll the eyes inwards or outwards.