Abadi R V, Whittle J P, Worfolk R
Department of Optometry and Vision Sciences, University of Manchester Institute of Science and Technology, England, United Kingdom.
Invest Ophthalmol Vis Sci. 1999 Feb;40(2):339-45.
To determine the relationship between retinal image movement (RIM) and oscillopsia in subjects with idiopathic congenital nystagmus (CN).
Eye movements were recorded using an IRIS infrared system. The eye movement signal was fed back to move an otherwise stationary target on a screen and thereby modify the RIM experienced by each of the five CN subjects. The target was present with either no background (the absolute condition) or a textured background (the relative condition). Feedback gains were varied from -1.0 (i.e., 100% retinal image increase) to +1.0 (i.e., 100% retinal image decrease or complete stabilization), with 0 representing the zero feedback or stationary target condition. In the first experiment, RIM thresholds were determined for a range of feedback values. Using zero feedback, a second experiment measured the detection threshold for absolute and relative motions to a ramp-generated target movement for five CN and five control subjects.
Under feedback control spatial constancy broke down for both increased and reduced RIM. The range of spatial constancy was greater for absolute (-0.56 to +0.44) compared with relative (-0.18 to +0.18) RIM. Motion detection thresholds for the CN group were 8 times less sensitive to the absolute and 17 times less sensitive to the relative motion of the target compared with the control group.
These results suggest that in CN subjects perceptual stability is achieved primarily by extraretinal signals.
确定特发性先天性眼球震颤（CN）患者视网膜图像运动（RIM）与视振荡之间的关系。
使用IRIS红外系统记录眼动。眼动信号被反馈以移动屏幕上原本静止的目标，从而改变五名CN患者各自所经历的RIM。目标呈现时要么没有背景（绝对条件），要么有纹理背景（相对条件）。反馈增益从-1.0（即视网膜图像增加100%）到+1.0（即视网膜图像减少100%或完全稳定）变化，0代表零反馈或静止目标条件。在第一个实验中，确定了一系列反馈值的RIM阈值。使用零反馈，第二个实验测量了五名CN患者和五名对照受试者对斜坡产生的目标运动的绝对和相对运动的检测阈值。
在反馈控制下，RIM增加和减少时空间恒常性均被打破。与相对RIM（-0.18至+0.18）相比，绝对RIM（-0.56至+0.44）的空间恒常性范围更大。与对照组相比，CN组对目标绝对运动的运动检测阈值低8倍，对目标相对运动的运动检测阈值低17倍。
这些结果表明，在CN患者中，感知稳定性主要通过视网膜外信号实现。
