The Location Of Rectus Pulley In High Myopia By Dynamic MRI

Objective To study the location of rectus pulleys in high myopia by dynamic MRI.Methods The 1.5T Simens Sonata MR scanner was used to acquire MRI in 14 high myopic patients (22 orbits) by dynamic MRI technique. The patients department on refractive diopter , axis of eye ball and dysfunction of eye movements were divided into two groups : A group had no dysfunction of eye movements;B group had limitation of movement. Multiple contiguous quasi-coronal MRI images perpendicular to the orbital axis were acquired at primary gaze, supraduction, infraduction, abduction, and adduction. The three dimensions coordinate system was established on the center of eyeball as the original point. The area centroids of vertical rectus at secondary horizontal gaze and horizontal recti at secondary vertical gaze were then determined by Scion Image. Rectus paths were defined as the connection of the area centroids and plotted in a normalized oculocentric coordinate system. Inflection of each rectus path was then determined objectively using linear regression on rectus mean area centroid coordinates by SPSS11.5. The point of the biggest changes of slope rate in linear regression equation was defined as the functional locations of rectus pulley. And the result was comparedwith the normal control.Results In group A, all rectus Pulley function locations have no statistically significant compared with normal control (P>0.05) In group B, the function point of MR, SR, and IR rectus Pulley have no statistically significant compared with normal control (P>0.05). The LR rectus Pulley function points have statistically significant (P<0.01).The LR rectus Pulley function points significant inferior dislocation in temporal site. Between group A and group B, except the LR rectus pulley function location is significant inferior dislocation in temporal site (p<0.05),the others rector pulley function locations have no statistically significant (P>0.05).Conclusions The inferior dislocation in temporal site of LR rectus Pulley point maybe the main cause of dysfunction of eye movements in high myopia.