Abstract
Purpose :
To measure the length of the optic nerve during eye movement using three-dimensional magnetic resonance imaging (MRI).
Methods :
High-resolution MRI was acquired from 47 normal subjects during central and lateral gazes at 40°. The 3D MR images were reconstructed and superimposed using MRIcron and FSL software. Optic nerve segmentation, from the termination of the eyeball to the optic chiasm, was performed with ITK-SNAP, and the length of the center-line of optic nerve segmentation was measured using the VMTK software tool. Optic nerve length in central gaze and lateral gaze (abduction or adduction) was compared. Additionally, the correlation between changes in optic nerve length, axial distance, and intra-vitreous volume was confirmed.
Results :
The optic nerve and eyeball were successfully segmented and extracted using ITK-SNAP on MRI during central and lateral gaze in all subjects. The mean length of the optic nerve was 49.49±3.08 mm in central gaze, whereas it measured 51.45±3.08 mm in abduction and 51.62±2.86 mm in adduction, indicating a significant increase (P=0.008 and P=0.006, respectively). There were significant positive correlations between changes in optic nerve length and axial distance (abduction, r=0.467, P=0.038; adduction, r=0.480, P=0.032), as well as intra-vitreous volume (abduction, r=0.582, P=0.007; adduction, r=0.527, P=0.017).
Conclusions :
Optic nerve length significantly increased during eye movement compared to central gaze. Further study is necessary to investigate whether such changes in optic nerve length affect optic nerve function, such as optic nerve traction or associated optic nerve damage.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.