Affiliations: [a] Pacific University College of Optometry, Forest Grove, Oregon | [b] Schnurmacher Institute for Vision Research and Department of Vision Sciences, State University of New York, State College of Optometry, New York, New York
Note: [*] Reprint address: Karl Citek, Pacific University College of Optometry, Forest Grove, OR 97116.
Abstract: The positions of both eyes were measured objectively in the dark following “look straight ahead” instructions for 16 subjects at 27 combinations of static pitch and roll postures over 360° of space, using an infrared video technique. Shifts in vertical version, or the doll reflex, varied sinusoidally with pitch and roll angle. At 0° roll, the average response has a peak-to-trough amplitude of 9.28° and is symmetric about a downward eye position of 4.63°. The proposed Dual Otolith Model (DOM), based on a combination of utricular and saccular inputs, provided excellent fits to the present data (R2=0.876) and to the data of previous studies (R2=0.916 to 0.994). Deviations in horizontal version varied sinusoidally with roll angle, with no significant effect of pitch angle. In general, clockwise (right-ear-down) rolls produced rightward eye movements, and counterclockwise (Ieft-ear-down) rolls produced leftward eye movements. The average versions were symmetric about a leftward eye position of 1.14°, with a peak-to-trough amplitude of 3.76°. The data were well represented by the proposed Horizontal Version Model (HVM; R2=0.796), which depended only on utricular input.
