Neuroscience 2002 Abstract
| Presentation Number: | 266.20 |
|---|---|
| Abstract Title: | MAGNETIC RESONANCE IMAGING (MRI) OF HUMAN EXTRAOCULAR MUSCLES (EOMS) IN ASYMMETRICAL ACCOMMODATIVE CONVERGENCE. |
| Authors: |
Demer, J. L.*1,2
; Kono, R.1
; Wright, W.1
1Jules Stein Eye Inst, Univ California Med Sch, Los Angeles, CA 2Neurology, Univ California Med Sch, Los Angeles, CA |
| Primary Theme and Topics |
Motor Systems - Oculomotor -- Head and eye movement |
| Session: |
266. Oculomotor: head and eye movements Poster |
| Presentation Time: | Monday, November 4, 2002 11:00 AM-12:00 PM |
| Location: | Hall A2-B3 G-12 |
| Keywords: | OCULOMOTOR, EYE MOVEMENT, EYE POSITION, VISION |
Rectus pulleys are predicted to shift in convergence (Clark et al, IOVS 41:3787, 2000). Tri-planar gadodiamide contrast MRI was obtained in 8 young adults during binocular fixation of a target aligned to one eye at 800 and 15 cm distance. EOM cross sections and paths were determined from area centroids. In convergence, the aligned eye rotated 0.3±0.6° (mean±SE) horizontally and 0.6±0.6° vertically with 0.6±0.1 mm lens thickening. The aligned globe moved anteriorly 0.2±0.5 mm. Focal cross section increases occurred with convergence in the aligned eye medial rectus (MR), lateral rectus (LR), and inferior oblique (IO), the latter increasing by 1.5±0.4 sq mm (P<0.05). The converging eye rotated nasally 22.4±0.8° and superiorly 0.5±0.5°, with 0.5±0.1 mm lens thickening. The converging globe moved anteriorly 0.2±0.5 mm. Interocular spacing decreased by 0.6±0.3 mm (P<0.05). The converging eye MR and LR had large contractile cross section changes, but IO also increased by 1.8±0.5 sq mm (P<0.05). Anterior paths of aligned eye rectus EOMs excyclo-shifted in convergence: 0.6 mm nasal shift of inferior rectus, 0.4 mm superior shift of MR, and 0.4 mm lateral shift of superior rectus, with equivocal inferior LR displacement. Similar changes for the converging eye were less evident due to adduction. Aligned eye EOM path shifts during asymmetric convergence suggest pulley movements independent of horizontal and vertical eye position, consistent with temporal tilting of Listing’s planes but differing from prediction. Rectus pulley array rotation around the orbital axis might be implemented bilaterally by the IO orbital layer and peribulbar smooth muscle.
Supported by EY08313 & RPB
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2002 Neuroscience Meeting Planner. Orlando, FL: Society for Neuroscience, 2002. Online.
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