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Infrared Video-Oculography an Innovational Technique for the Assessment of Ocular Cycloduction
Schworm H. D.,
Universitätsklinikum Hamburg-Eppendorf, Klinik und Poliklinik für Augenheilkunde, Bereich Orthoptik und Pleoptik (Hamburg)
Purpose: Objective assessment of torsional eye movements (cycloductions) is technically difficult and was therefore limited to highly equipped laboratory conditions so far. During the past years, use of the infrared technique for eye movement recordings proved to be of growing importance. The option for reliable registration of torsional eye movements, however, is relatively new.
Methods: On infrared video-oculography ("3D-VOG", Fa. SMI, Teltow, Germany), analysis of horizontal and vertical eye movements is achieved by tracking the change of position of the reflex-free pupillary zone ("black pupil technique"). Cycloductions are assessed by tracking an initially defined sector of the iris that rotates according to the ocular cycloduction. Several studies on the assessment of cycloduction under different conditions in healthy individuals as well as in patients with disturbances of the oblique eye muscles were carried out using this technique and are introduced in the present paper.
Results: Video-oculography allowed reliable recordings and detection of even small cycloductions at the order of 0.1°. Investigations in different head and body positions were achieved, e.g. the assessment of cycloductions during the Bielschowsky head tilt test which is of special interest for the strabismologist. The results provided new insights in cycloductional mechanisms and confirmed previous findings based on more tedious techniques. Limits of the method were observed with respect to the expenses for the recording equipment and the time consuming calibration and analysis procedure as well as the reduced applicability in children.
Conclusions: Although not yet suitable for the daily clinical routine investigation, infrared video-oculography proved to be a valuable and meanwhile indispensable innovational technique for the assessment of horizontal, vertical and especially cycloductional eye movements.