Knapp Christopher M, Gottlob Irene, McLean Rebecca J, Proudlock Frank A
University of Leicester, Ophthalmology Group, Faculty of Medicine and Biological Sciences, Leicester, UK.
Invest Ophthalmol Vis Sci. 2008 Feb;49(2):581-8. doi: 10.1167/iovs.07-0773.
Look optokinetic nystagmus (OKN) consists of voluntary tracking of details in a moving visual field, whereas stare OKN is reflexive and consists of shorter slow phases of lower gain. Horizontal OKN is symmetrical in healthy adults, whereas symmetry of vertical OKN is controversial. Horizontal and vertical look and stare OKN symmetry was measured, and the consistency of individual asymmetries and the effect of varying stimulus conditions were investigated.
Horizontal and vertical look and stare OKN gains were recorded in 15 healthy volunteers (40 degrees /s) using new methods to delineate look and stare OKN. Responses with right and left eye viewing were compared to investigate consistency of individual OKN asymmetry. In a second experiment, the symmetry of stare OKN was measured in nine volunteers varying velocity (20 degrees /s and 40 degrees /s), contrast (50% and 100%), grating contrast profile (square or sine wave), and stimulus shape (full screen or circular vignetted).
There was no horizontal or vertical asymmetry in look or stare OKN gain for all volunteers grouped together. However, individual vertical asymmetries were strongly correlated for left and right eye viewing (look: r = 0.77, P = 0.0008; stare: r = 0.75, P = 0.001) and for look and stare OKN (r = 0.66, P = 7.3 x 10(-5)) because of a strong correlation for downward moving stimuli (r = 0.73, P = 0.002). Horizontal and vertical asymmetries were not significantly affected by variations in stimulus parameter.
Although no horizontal or vertical OKN asymmetries existed for volunteers grouped together, vertical OKN was characterized by idiosyncratic asymmetries that remained consistent for an individual. Look and stare OKN gain is strongly associated for downward moving stimuli.
注视视动性眼震（OKN）包括对移动视野中细节的自主追踪，而凝视OKN是反射性的，其慢相较短且增益较低。健康成年人的水平OKN是对称的，而垂直OKN的对称性存在争议。测量了水平和垂直注视及凝视OKN的对称性，并研究了个体不对称性的一致性以及不同刺激条件的影响。
使用新方法描绘注视和凝视OKN，记录了15名健康志愿者（40度/秒）的水平和垂直注视及凝视OKN增益。比较右眼和左眼观察的反应，以研究个体OKN不对称性的一致性。在第二个实验中，测量了9名志愿者在不同速度（20度/秒和40度/秒）、对比度（50%和100%）、光栅对比度分布（方形或正弦波）以及刺激形状（全屏或圆形渐晕）下凝视OKN的对称性。
所有志愿者的注视或凝视OKN增益在水平或垂直方向上均无不对称性。然而，由于向下移动刺激的强相关性（r = 0.73，P = 0.002），个体垂直不对称性在右眼和左眼观察时（注视：r = 0.77，P = 0.0008；凝视：r = 0.75，P = 0.001）以及注视和凝视OKN之间（r = 0.66，P = 7.3×10⁻⁵）具有强相关性。水平和垂直不对称性不受刺激参数变化的显著影响。
虽然所有志愿者作为一个整体时不存在水平或垂直OKN不对称性，但垂直OKN的特点是个体特异性的不对称性，且个体保持一致。注视和凝视OKN增益与向下移动刺激密切相关。
