磁気共鳴画像を用いた強度近視性斜視の眼球と眼窩の不均衡と眼球形状の定量評価

Purpose: The imbalance between the globe and orbit, that is, the volume ratio of the globe to the orbit（GOR）, and ratio of the equatorial diameter of the globe to the axial length（AL）（EAR）（an indicator of globe shape）were evaluated quantitatively using magnetic resonance imaging （MRI）in patients with highly myopic strabismus（HMS）. Subjects and Methods: This was a retrospective case-series study, involving three patients（six eyes）with HMS. Globe volume, bony orbital volume, and the equatorial diameter of the globe were measured on MRI using image analysis software products. AL was measured using a biometer based on optical coherence tomography. The GOR and EAR were calculated. Results: The right eye of one patient has a normal globe with a normal AL（24.06 mm）. The GOR and EAR were 0.34 and 1.01, respectively. The other five globes showed a posterior staphyloma and long AL（28.62-34.20 mm）. Their GOR and EAR ranged from 0.38 to 0.44 and 0.75 to 0.85, respectively（which were larger and smaller, respectively, than those of the normal globe）. Conclusion: The globes of HMS patients exhibited an increased GOR and decreased EAR, producing elongated spheres, in which the AL functioned as the axis of rotation.