THE DEVELOPMENT OF VISUAL PURSUIT DURING THE FIRST MONTHS OF LIFE

Background: Then are few previous investigations of smooth pursuit in infants. The aim of our study was to quantify visual pursuit in infant s between 1 day and 16 weeks of age. Methods:Eye movements of 97 healt hy infants between 1 day and 16 weeks of age were recorded one to seve n times with infrared photo-oculography. For stimulation of visual pur suit a square of 9.4 deg of visual angle with vertical gratings moved horizontally at a constant velocity of 7.5 deg/s. Results: In the firs t 2 weeks of life, segments of smooth pursuit were measured with a max imum velocity of 7.93 deg/s, with a maximum gain of 1.06 and a maximal duration of 3.16 s. In sequential recordings no significant increases of velocity, gain or duration were found. However, the total time the subjects followed the stimulus with smooth plus saccadic pursuit incr eased significantly with age (from a median of 39.0% to a median of 61 .5% of examination time). Conclusion: This study clearly demonstrates that smooth pursuit is already present in the first week of life. We f ound no significant increase in velocity, gain and duration of smooth pursuit segments in the first 16 weeks of life with our recording tech nique. However, the total pursuit time, reflecting attention, increase d with age. The ocular machinery to drive pursuit appears to be in pla ce at birth and seems not to be influenced by increased attention in t he first months of life.