Teufel Julian, Bardins S, Spiegel Rainer, Kremmyda O, Schneider E, Strupp M, Kalla R
Department of Neurology and German Center for Vertigo and Balance Disorders, Ludwig-Maximilans-University Munich, Marchioninistr. 15, 81377, Munich, Germany.
Division of Internal Medicine, Basel University Hospital, Am Petersgraben 4, 4031, Basel, Switzerland.
J Neuroeng Rehabil. 2016 Jan 4;13:1. doi: 10.1186/s12984-015-0109-2.
Patients with downbeat nystagmus syndrome suffer from oscillopsia, which leads to an unstable visual perception and therefore impaired visual acuity. The aim of this study was to use real-time computer-based visual feedback to compensate for the destabilizing slow phase eye movements.
The patients were sitting in front of a computer screen with the head fixed on a chin rest. The eye movements were recorded by an eye tracking system (EyeSeeCam®). We tested the visual acuity with a fixed Landolt C (static) and during real-time feedback driven condition (dynamic) in gaze straight ahead and (20°) sideward gaze. In the dynamic condition, the Landolt C moved according to the slow phase eye velocity of the downbeat nystagmus. The Shapiro-Wilk test was used to test for normal distribution and one-way ANOVA for comparison.
Ten patients with downbeat nystagmus were included in the study. Median age was 76 years and the median duration of symptoms was 6.3 years (SD +/- 3.1y). The mean slow phase velocity was moderate during gaze straight ahead (1.44°/s, SD +/- 1.18°/s) and increased significantly in sideward gaze (mean left 3.36°/s; right 3.58°/s). In gaze straight ahead, we found no difference between the static and feedback driven condition. In sideward gaze, visual acuity improved in five out of ten subjects during the feedback-driven condition (p = 0.043).
This study provides proof of concept that non-invasive real-time computer-based visual feedback compensates for the SPV in DBN. Therefore, real-time visual feedback may be a promising aid for patients suffering from oscillopsia and impaired text reading on screen. Recent technological advances in the area of virtual reality displays might soon render this approach feasible in fully mobile settings.
下跳性眼球震颤综合征患者会出现视振荡，这会导致视觉感知不稳定，进而损害视力。本研究的目的是利用基于计算机的实时视觉反馈来补偿不稳定的慢相眼球运动。
患者坐在电脑屏幕前，头部固定在下巴托上。眼球运动由眼动追踪系统（EyeSeeCam®）记录。我们在直视和（20°）侧视时，使用固定的兰道环C（静态）和实时反馈驱动条件（动态）测试视力。在动态条件下，兰道环C根据下跳性眼球震颤的慢相眼球速度移动。使用夏皮罗-威尔克检验来检验正态分布，并使用单因素方差分析进行比较。
本研究纳入了10名下跳性眼球震颤患者。中位年龄为76岁，症状的中位持续时间为6.3年（标准差±3.1年）。直视时平均慢相速度适中（1.44°/秒，标准差±1.18°/秒），侧视时显著增加（平均左侧3.36°/秒；右侧3.58°/秒）。在直视时，我们发现静态和反馈驱动条件之间没有差异。在侧视时，10名受试者中有5名在反馈驱动条件下视力有所改善（p = 0.043）。
本研究提供了概念验证，即基于计算机的非侵入性实时视觉反馈可补偿下跳性眼球震颤中的慢相速度。因此，实时视觉反馈可能是对视振荡和屏幕上文本阅读受损患者有前景的辅助手段。虚拟现实显示领域的最新技术进展可能很快使这种方法在完全移动的环境中可行。
