The retinal nerve fiber layer (RNFL) is a fibrous tissue that shows form birefringence. This optical tissue property is related to the microstructure of the nerve fiber axons that carry electrical signals from the retina to the brain. Ocular diseases that are known to cause neurologic changes, like glaucoma or diabetic retinopathy (DR), might alter the birefringence of the RNFL, which could be used for diagnostic purposes. In this pilot study, we used a state-of-the-art polarization sensitive optical coherence tomography (PS-OCT) system with an integrated retinal tracker to analyze the RNFL birefringence in patients with glaucoma, DR, and in age-matched healthy controls. We recorded 3D PS-OCT raster scans of the optic nerve head area and high-quality averaged circumpapillary PS-OCT scans, from which RNFL thickness, retardation and birefringence were derived. The precision of birefringence measurements was 0.005°/µm. As compared to healthy controls, glaucoma patients showed a slightly reduced birefringence (0.129 vs. 0.135°/µm), although not statistically significant. The DR patients, however, showed a stronger reduction of RNFL birefringence (0.103 vs. 0.135°/µm) which was highly significant. This result might open new avenues into early diagnosis of DR and related neurologic changes.

中文翻译：

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偏振敏感OCT分析青光眼和糖尿病性视网膜病变患者的视网膜神经纤维层双折射

视网膜神经纤维层（RNFL）是显示双折射形式的纤维组织。这种光学组织特性与将电信号从视网膜传递到大脑的神经纤维轴突的微观结构有关。已知会引起神经系统变化的眼部疾病，例如青光眼或糖尿病性视网膜病（DR），可能会改变RNFL的双折射，可将其用于诊断目的。在这项先导研究中，我们使用了最先进的偏振敏感光学相干断层扫描（PS-OCT）系统和集成的视网膜追踪器来分析青光眼，DR和年龄匹配的健康对照者的RNFL双折射。我们记录了视神经乳头区域的3D PS-OCT光栅扫描和高质量的平均乳头状乳头PS-OCT扫描，由此得出RNFL厚度，延迟和双折射。双折射测量的精度为0.005°/μm。与健康对照组相比，青光眼患者的双折射略有降低（0.129 vs. 0.135°/ µm），尽管在统计学上没有统计学意义。然而，DR患者表现出更强的RNFL双折射降低（0.103对0.135°/ µm）。这一结果可能为早期诊断DR和相关的神经系统改变开辟新的途径。