[Equipment and technic allowing a quantitative study of pursuit eye movements and saccadic movements]

Study of following eye movements (posterior oculogyric pathway) and saccadic eye movements (anterior oculogyric pathway) represents the principal advance in nystagmography in the past ten years. Use as a visual stimulus of the LED bar developed by one of the authors (E.U.) has proved to be clinically easy and gave results identical to those of the reference stimulation system (laser + mobile mirror). It is possible to quantify performance and abnormalities of these two oculogyric pathways using parameters calculated: - either using a micro-computer (Aurelia); - or manually following a technique which the authors describe in detail indicating normal results and limits in their variations. These parameters for the foveal following system are gain and total movement. For the saccadic system, they are the maximum speed of the saccade, latent period and its accuracy. Using such quantitative analysis, it has become possible not only to draw a distinction between peripheral and central disorders, but also to describe different topographical groups: lesion of the cerebellopontine angle, cerebellar lesion, intrinsic lesion of the brain stem or parietal lesion. These different patterns are illustrated by examples.