Demer J L, Honrubia V, Baloh R W
Jules Stein Eye Institute, Comprehensive Division, UCLA 90024-7002, USA.
Am J Otol. 1994 May;15(3):340-7.
A method has been developed of clinically quantifying dynamic visual acuity (DVA), the acuity during imposed head motion in the pitch axis. In this method, visual acuity is measured using a computer-controlled projection system during vertical, sinusoidal relative motion either of the optotypes (the letters to be read) or of a servodriven swinging chair in which subjects are seated. In normal persons, the vestibulo-ocular reflex (VOR) functions adequately during imposed head movements to limit retinal image instability, making DVA independent of head velocity. During head movements the wearing of telescopic spectacles, which magnify the visual effects, can overwhelm even normal visual-vestibular interactions, producing retinal image instability leading to creation of artificial experimental oscillopsia in normal subjects. With the head stationary, optotype motion at frequencies and velocities beyond the capabilities of visual tracking also results in retinal image motion. Using these methods, DVA for both optotype and head motion was found to be degraded in a predictable fashion when the velocity of the image on the retina exceeded 2 degrees per second. In two patients with total peripheral vestibular loss, DVA was markedly impaired during head motion. As a result of the VOR deficit, this impairment of DVA was observed, even without the use of telescopic spectacles, and was predictably related to the velocity of imposed head motion. Dynamic visual acuity during imposed head motion is a quantitative and clinically feasible measure of oscillopsia that reflects functionally significant abnormalities of the VOR.
已经开发出一种临床上定量动态视力（DVA）的方法，即俯仰轴上头部运动时的视力。在这种方法中，在垂直、正弦相对运动期间，使用计算机控制的投影系统测量视力，这种相对运动可以是视标（待读取的字母）的运动，也可以是受试者所坐的伺服驱动摇椅的运动。在正常人中，前庭眼反射（VOR）在施加头部运动期间能充分发挥作用，以限制视网膜图像的不稳定性，使DVA与头部速度无关。在头部运动期间，佩戴放大视觉效果的望远镜式眼镜，甚至会使正常的视觉 - 前庭相互作用不堪重负，产生视网膜图像不稳定，导致在正常受试者中产生人为的实验性视振荡。头部静止时，视标以超出视觉跟踪能力的频率和速度运动也会导致视网膜图像运动。使用这些方法发现，当视网膜上图像的速度超过每秒2度时，视标和头部运动的DVA都会以可预测的方式下降。在两名完全性外周前庭丧失的患者中，头部运动期间DVA明显受损。由于VOR缺陷，即使不使用望远镜式眼镜也观察到这种DVA受损情况，并且可预测地与施加的头部运动速度有关。施加头部运动期间的动态视力是一种对视振荡进行定量且临床上可行的测量方法，它反映了VOR功能上的显著异常。
