Endo Takao, Hozumi Kenta, Hirota Masakazu, Kanda Hiroyuki, Morimoto Takeshi, Nishida Kohji, Fujikado Takashi
Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
Department of Applied Visual Science, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
Graefes Arch Clin Exp Ophthalmol. 2019 Aug;257(8):1765-1770. doi: 10.1007/s00417-019-04375-2. Epub 2019 May 30.
Our aim is to develop a new generation of suprachoroidal-transretinal stimulation (STS) retinal prosthesis using a dual-stimulating electrode array to enlarge the visual field. In the present study, we aimed to examine how position and size of the visual field-created by a retinal prosthesis simulator-influenced mobility.
Twelve healthy subjects wore retinal prosthesis simulators. Images captured by a web camera attached to a head-mounted display (HMD) were processed by a computer and displayed on the HMD. Three types of artificial visual fields-designed to imitate phosphenes-obtained by a single (5 × 5 electrodes; visual angle, 15°) or dual (5 × 5 electrodes ×2; visual angle, 30°) electrode array were created. Visual field (VF)1 is an inferior visual field, which corresponds to a dual-electrode array implanted in the superior hemisphere. VF2 is a superior visual field, which corresponds to a single-electrode array implanted in the inferior hemisphere. VF3 is a superior visual field, which corresponds to a dual-electrode array implanted in the inferior hemisphere. In each type of artificial visual field, a natural circular visual field (visual angle, 5°) which imitated the vision of patients with advanced retinitis pigmentosa existed at the center. Subjects were instructed to walk along a black carpet (6 m long × 2.2 m wide) without stepping on attached white circular obstacles. Each obstacle was 20 cm in diameter, and obstacles were installed at 40-cm intervals. We measured the number of footsteps on the obstacles, the time taken to complete the obstacle course, and the extent of head movement to scan the area (head-scanning). We then compared the results recorded from these 3 types of artificial visual field.
The number of footsteps on obstacles was lowest in VF3 (One-way ANOVA; P = 0.028, Fisher's LSD; VF 1 versus 3 P = 0.039, 2 versus 3 P = 0.012). No significant difference was observed for the time to complete the obstacle course or the extent of head movement between the 3 visual fields.
The superior and wide visual field (VF3) obtained by the retinal prosthesis simulator resulted in better mobility performance than the other visual fields.
我们的目标是开发新一代的脉络膜上腔-视网膜刺激（STS）视网膜假体，使用双刺激电极阵列来扩大视野。在本研究中，我们旨在研究视网膜假体模拟器所产生的视野的位置和大小如何影响移动性。
12名健康受试者佩戴视网膜假体模拟器。连接到头戴式显示器（HMD）的网络摄像头拍摄的图像由计算机处理并显示在HMD上。创建了三种类型的人工视野，设计用于模仿通过单个（5×5电极；视角，15°）或双（5×5电极×2；视角，30°）电极阵列获得的光幻视。视野（VF）1是下视野，对应于植入上半球的双电极阵列。VF2是上视野，对应于植入下半球的单电极阵列。VF3是上视野，对应于植入下半球的双电极阵列。在每种类型的人工视野中，中央存在一个模仿晚期视网膜色素变性患者视力的自然圆形视野（视角，5°）。受试者被指示沿着黑色地毯（6米长×2.2米宽）行走，不要踩到附着的白色圆形障碍物。每个障碍物直径为20厘米，障碍物以40厘米的间隔安装。我们测量了踩在障碍物上的步数、完成障碍路线所需的时间以及扫描该区域的头部移动程度（头部扫描）。然后我们比较了从这三种类型的人工视野记录的结果。
VF3中踩在障碍物上的步数最少（单因素方差分析；P = 0.028，Fisher最小显著差异法；VF 1与3比较，P = 0.039，2与3比较，P = 0.012）。在三个视野之间，完成障碍路线的时间或头部移动程度没有观察到显著差异。
视网膜假体模拟器获得的上宽视野（VF3）比其他视野具有更好的移动性能。
