Magnetic Resonance Imaging Analysis of Anterior and Posterior Eye Segment Displacement during Ocular Gaze Shifts

Abstract

Purpose To determine the relationship between movements of the posterior and anterior eye segments during arbitrary gaze shifts and to obtain information for monitoring fixation during radiotherapy for ocular diseases. Methods We examined eye movements of ten emmetropic volunteers in a 1.5 T magnetic resonance system. Using a T2-weighted ultrafast turbo-spin echo sequence (UTSE), the eyes were examined within 21 seconds. Sagittal and transversal eye slices were obtained in five passages in five gaze directions (straight ahead, 15° above, 15° below, 15° right and 15° left of the primary position). Displacement of the posterior eye segment was analyzed in relation to the movement of the anterior segment in all directions. Results The relationship between the movements of the anterior and posterior eye segment was 1:0.8 (± 0.06 SD) during horizontal gaze shifts and 1:1.16 (± 0.11 SD) during vertical gaze shifts. Conclusions Magnetic resonance imaging showed that the relationship between anterior and posterior eye segments was different during horizontal and vertical eye movements, indicating the presence of more than one center of rotation. Compared to the anterior eye segment, there was less displacement of the posterior eye segment during horizontal eye movements and more displacement during vertical eye movements.