Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA.
Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, USA.
Curr Eye Res. 2023 May;48(5):518-527. doi: 10.1080/02713683.2023.2172185. Epub 2023 Feb 27.
The optic nerve mechanically loads the eye during ocular rotation, thus altering the configuration of the disk and peripapillary tissues. We used optical coherence tomography (OCT) angiography (OCTA) to investigate mechanical strains and volume changes in disk and peripapillary blood vessels during horizontal duction.
Structural OCT and OCTA were performed centered on optic disks; imaging was repeated in central gaze, and in 30° ab- and adduction. By an algorithm employing point-set registration of 3 D features, we developed a novel approach for measuring disk strains, and strains and volumes of the blood vessels associated with horizontal duction. Repeatability was demonstrated in each gaze position.
19 eyes of 10 healthy adults of average age 37 ± 15 (standard deviation, SD) years were imaged. The method was validated by demonstrating numerically consistent vascular volumes and strains for repeated imaging under identical conditions. Compared with central gaze, vascular volume increased by 5.2 ± 4.1% in adduction. Adduction and abduction caused strains of 3.0 ± 1.6% and 2.6 ± 1.8% in the optic disk, whereas blood vessels showed greater strains of 8.1 ± 1.3% and 8.2 ± 1.7%. Decomposition of strain components depending on directionality and regions demonstrated that adduction induces significant net tensile strains, suggesting traction exerted by the optic nerve. The decomposition also showed that nasotemporal compressive strains are larger in temporal hemidisks than nasal hemidisks. The Bruch's membrane opening was significantly compressed horizontally in adduction by 1.1% ( = .009).
This novel analysis combining structural OCT and OCTA demonstrates that optic disk compression during adduction is associated with disk and vascular strains much larger than reported for intraocular pressure elevation and pulsatile perfusion, as well as compressing the disk and increasing peripapillary vascular volume. These changes may be relevant to the pathogenesis of optic nerve and retinal vascular disorders.
眼球旋转时，视神经对眼球产生机械性负荷，从而改变视盘和视盘周围组织的形态。我们使用光相干断层扫描（OCT）血管造影（OCTA）来研究水平牵引时视盘和视盘周围血管的机械应变和体积变化。
以视盘为中心进行结构 OCT 和 OCTA 成像；在注视中央和 30°外展和内收时重复成像。我们通过使用 3D 特征点集配准的算法，开发了一种测量视盘应变和与水平牵引相关的血管应变和体积的新方法。在每个注视位置均验证了可重复性。
共对 10 名平均年龄 37±15 岁（标准差）的健康成年人的 19 只眼进行了成像。通过证明在相同条件下重复成像时血管体积和应变具有数值一致性，验证了该方法的有效性。与注视中央相比，内收时血管体积增加了 5.2±4.1%。外展和内收使视盘产生 3.0±1.6%和 2.6±1.8%的应变，而血管则产生 8.1±1.3%和 8.2±1.7%的较大应变。根据方向和区域分解应变分量表明，内收会引起明显的净拉伸应变，提示视神经产生的牵引力。该分解还表明，颞半盘的鼻颞向压缩应变大于鼻半盘。在 30°内收时，Bruch 膜开口水平方向的压缩为 1.1%（ = .009）。
本研究结合结构 OCT 和 OCTA 的新型分析表明，内收时视盘压缩与视盘和血管应变的相关性大于报道的眼压升高和脉动灌注，还会引起视盘压缩和增加视盘周围血管体积。这些变化可能与视神经和视网膜血管疾病的发病机制有关。
