STUDY OF STRABISMUS USING A VIRTUAL REALITY SYSTEM

视觉系统的功能是将三维世界感知为二维视网膜图像，并使用立体键（如双眼视差、大小、阴影、阴影、纹理、运动等）重建它。本研究的目的是阐明正常或斜视患者在何种条件下使用这些键中的哪一个。该系统由液晶显示屏（LCD）和使用红外摄像机的眼睛位置/运动监测系统组成。两个CCD彩色摄像机，其视野类似于LCD屏幕，以65 mm的间隔连接到HMD。每个摄像机连接到一个LCD屏幕，以便投影的图像与受试者看到的图像相同。戴上HMD，受试者可以正常观看。通过改变摄像机与显示屏的连接方式，产生正常双眼视差、反向视差和非视差，并对正常人和斜视者进行观察。在正常和反向双眼视差下进行立体视觉测试，正常受试者在正常双眼视差下感觉到正常的立体视觉。被试能正确识别书本、人脸、桌椅等被试所熟悉的物体的具有反向视差的立体形状。当他们看到复杂的东西，如纠结的绳子时，他们感到困惑，在这种情况下，他们没有通过环和钩测试。斜视被试在正常视差和反向视差下几乎都能正确识别立体形状。只有在环在正常视差和反向视差条件下移动时，才能通过环钩试验，表明斜视患者比正常人更多地使用单眼立体视键，以补充其双眼视差感知的不足。

The function of the visual system is to perceive the three dimensional world as two dimensional retinal images and to reconstruct it using stereoscopic keys such as binocular parallax, size, shadows, shades, textures, motion, etc. The purpose of this study is to clarify which of these keys are used under which conditions by normal or strabismic patients.A head mounted display (HMD) was made, which was composed of liquid crystal display panels (LCD) and eye position/movement monitoring systems using infrared video camera. Two CCD color video cameras whose field of vision was similar to those of the LCD screens, were attached to the HMD at intervals of 65 mm. Each camera was connected to one LCD screen so that the image projected was the same as the subjects were seeing. Wearing the HMD the subjects could see normally. Changing the connections between video cameras and screens, the normal binocular parallax, reversed parallax or non parallax were created.Normal and strabismic subjects were investigated. Stereoscopic tests were performed under normal and reversed binocular parallax.Normal subjects felt normal stereopsis with normal binocular parallax. The could correctly recognize the stereoscopic shape with reversed parallax of the objects were familiar for the subjects such as books, faces, desks or chairs. They were confused when they saw complicated things such as tangled ropes, and they failed ring and hook test in this condition. Strabismic subjects could almost correctly recognize the stereoscopic shape with both normal and reversed parallax. They passed the ring and hook test only when the ring was moving in both normal and reversed parallax conditions.It is suggested that strabismic patients used monocular stereoptic keys more than normal persons to supplement their lack of binocular rarallax perception.