Aleci Carlo, Piana Giulio, Anselmino Franco
Department of Ophthalmology, Gradenigo Hospital, C.so R. Margherita 8, 10153 Turin, Italy.
Open Ophthalmol J. 2010 May 31;4:15-21. doi: 10.2174/1874364101004010015.
Spatial relationship perception (SRP), defined as the function able to detect the difference between the perceived extent of a shape along the x/y cardinal coordinates, has been investigated in 42 eyes of 21 emmetropic subjects by means of a psychophysical test conceived on purpose. Aiming to the highest sensibility and since curvature detection is reckoned as an hyperacuity, elliptical stimuli have been chosen to measure the spatial relationship anisotropy (SRA) in the visual system. Observers turned out to be able to detect curvature differences along the elliptical contour as low as 33.6 sec arc, which in terms of SRP means an aspect ratio (i.e. the ratio between the height and the width of the ellipse) as low as 1.0022-1.0035. By comparing these results with those obtained in previous investigations from other curvature discrimination tasks, it is argued that recognition threshold is conditioned by the amount of space anisotropy of the visual system. Indeed, in about half of the recruited subjects, vertical/horizontal anisotropy is found to a certain extent and such SRA correlates with the recognition threshold (r= 0.69, p<0.01). There is direct evidence of visual spatial distortion and in particular increased anisotropy in neuro-ophtalmological diseases such as hemianopia and around scotomatous regions in the visual field. Thence, apart from theoretical considerations in physiological field, results collected in this study may be regarded as normative data for future clinical investigations.
空间关系感知（SRP）被定义为一种能够检测沿x/y直角坐标感知到的形状范围差异的功能。通过专门设计的心理物理学测试，对21名正视眼受试者的42只眼睛进行了研究。为了达到最高的灵敏度，并且由于曲率检测被认为是一种超敏锐度，因此选择了椭圆形刺激来测量视觉系统中的空间关系各向异性（SRA）。结果发现，观察者能够检测到沿椭圆轮廓低至33.6秒弧度的曲率差异，就SRP而言，这意味着纵横比（即椭圆的高度与宽度之比）低至1.0022 - 1.0035。通过将这些结果与先前其他曲率辨别任务的研究结果进行比较，有人认为识别阈值受视觉系统空间各向异性量的制约。事实上，在大约一半的受试对象中，发现了一定程度的垂直/水平各向异性，并且这种SRA与识别阈值相关（r = 0.69，p <0.01）。有直接证据表明存在视觉空间扭曲，特别是在诸如偏盲等神经眼科疾病以及视野中暗点区域周围，各向异性增加。因此，除了生理领域的理论考虑之外，本研究收集的结果可被视为未来临床研究的规范数据。
