Objective Visual Accuity Test Using Optokinetic Nystagmus

本研究旨在探讨视动性眼震（OKN）作为重度残疾儿童和婴幼儿视力客观检查的可能性。本文对30例转鼓所致弱智儿童的OKN进行了测定。儿童的注意力和厌恶反应对实验结果有一定影响。然后探讨了OKN的视敏度检测需要哪些条件，在正常视力、屈光不正、浑浊和视野缺损条件下，视标大小和视标速度对OKN的诱发有何影响。在正常视力条件下，目标尺寸越细，目标运动越慢，OKN就越容易诱发。当靶大小为25“时，诱发OKN的靶速度为500- 750 Hz，而靶大小为25”时，视敏度为0.04。因此，我们需要两个参数来推测OKN的视敏度，这两个参数是目标的大小和速度。在屈光不正和不透明条件下，当目标尺寸较薄时，需要更慢的目标速度。除视力外，其他视觉因素也会影响OKN的幅值和一个周期的时间，因此OKN是一种非常有用的视力检查方法。因此，我们更需要在各种视觉障碍条件下的OKN研究。

The aim of this research is to examine the possibility of Optokinetic Nystagmus (OKN) as an objective visual acuity test for sever-multiple handicapped children and infants. We measured the OKN of 30 mentally retarded children induced by turning drum. The result appeared to be affected by attention of children or aversive response. Then we examined what conditions need to measure the visual acuity from OKN.How do visual target size and speed affect inducing OKN under normal sighted condition, refractive error condition, opacity condition and visual field defect condition ? Under normal sighted condition, the more thin the target size is, the more slowly the target need to move for OKN to be induced. When the target size is 25', the target speed is 500-750Hz for inducing OKN.But, the target 25' size is 0.04 as visual acuity. So we need two parameters to speculate the visual acuity from OKN.These are target size and speed. Under refractive error and opacity condition, when the target size is thin, we need more slow target speed. In addition to the visual acuity, other visual factors affect the amplitude of OKN and the time of one cycle.We conclude from this research that OKN is very useful clinical method as visual acuity test for sever-multiple handicapped children. So we need OKN research under various visual handicapped conditions still more.