Dynamic analysis of head movements by means of a three-dimensional position measurement system

By using a newly devised three-dimensional position measurement system, head movements of a normal subject and a patient with congenital strabismus were studied. This system consists of both infrared light-emitting diodes and position-sensitive diodes, which lead to high accuracy and high-frequency response with a position accuracy within 1 mm and angular accuracy within 1 degree. The electro-oculograph was used for measuring ocular movements. The power spectra of head and eye movements showed a similar frequency component and a similar frequency response with respect to the signal inputs of head movements, so there is a close correlation between the two movements.