Wang Xiaofei, Beotra Meghna R, Tun Tin Aung, Baskaran Mani, Perera Shamira, Aung Tin, Strouthidis Nicholas G, Milea Dan, Girard Michaël J A
Ophthalmic Engineering & Innovation Laboratory, Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore.
Ophthalmic Engineering & Innovation Laboratory, Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore 2Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
Invest Ophthalmol Vis Sci. 2016 Oct 1;57(13):5825-5833. doi: 10.1167/iovs.16-20560.
To measure lamina cribrosa (LC) strains (deformations) following abduction and adduction in healthy subjects and to compare them with those resulting from a relatively high acute intraocular pressure (IOP) elevation.
A total of 16 eyes from 8 healthy subjects were included. Among the 16 eyes, 11 had peripapillary atrophy (PPA). For each subject, both optic nerve heads (ONHs) were imaged using optical coherence tomography (OCT) at baseline (twice), in different gaze positions (adduction and abduction of 20°) and following an acute IOP elevation of approximately 20 mm Hg from baseline (via ophthalmodynamometry). Strains of LC for all loading scenarios were mapped using a three-dimensional tracking algorithm.
In all 16 eyes, LC strains induced by adduction and abduction were 5.83% ± 3.78% and 3.93% ± 2.57%, respectively, and both significantly higher than the control strains measured from the repeated baseline acquisitions (P < 0.01). Strains of LC in adduction were on average higher than those in abduction, but the difference was not statistically significant (P = 0.07). Strains of LC induced by IOP elevations (on average 21.13 ± 7.61 mm Hg) were 6.41% ± 3.21% and significantly higher than the control strains (P < 0.0005). Gaze-induced LC strains in the PPA group were on average larger than those in the non-PPA group; however, the relationship was not statistically significant.
Our results confirm that horizontal eye movements generate significant ONH strains, which is consistent with our previous estimations using finite element analysis. Further studies are needed to explore a possible link between ONH strains induced by eye movements and axonal loss in optic neuropathies.
测量健康受试者外展和内收后筛板（LC）应变（变形），并将其与相对较高的急性眼压（IOP）升高所产生的应变进行比较。
纳入8名健康受试者的16只眼睛。在这16只眼睛中，11只患有视盘周围萎缩（PPA）。对于每位受试者，在基线时（两次）、不同注视位置（内收和外展20°）以及从基线急性眼压升高约20 mmHg后（通过眼动脉压测定法），使用光学相干断层扫描（OCT）对双眼视神经乳头（ONH）进行成像。使用三维跟踪算法绘制所有加载情况下的LC应变图。
在所有16只眼睛中，内收和外展引起的LC应变分别为5.83%±3.78%和3.93%±2.57%，两者均显著高于从重复基线采集测量的对照应变（P<0.01）。内收时的LC应变平均高于外展时，但差异无统计学意义（P = 0.07）。眼压升高（平均21.13±7.61 mmHg）引起的LC应变为6.41%±3.21%，显著高于对照应变（P<0.0005）。PPA组中注视引起的LC应变平均大于非PPA组；然而，这种关系无统计学意义。
我们的结果证实水平眼球运动产生显著的ONH应变，这与我们之前使用有限元分析的估计结果一致。需要进一步研究以探索眼球运动引起的ONH应变与视神经病变中轴突损失之间的可能联系。
