Katz L M, Levi D M, Bedell H E
Doc Ophthalmol. 1984 Dec 15;58(4):351-73. doi: 10.1007/BF00679799.
The purpose of the present study was to establish the extent of the amblyopic deficit at 0 degree, 10 degrees, and 20 degrees retinal eccentricity using contrast sensitivity measures for sine wave gratings subtending various field sizes. Contrast sensitivity functions were shown to vary with stimulus field size, retinal location and degree of amblyopia. Foveally, peak contrast sensitivity of amblyopic eyes increased markedly with increasing field size, to reach the same magnitude as that of the contralateral non-amblyopic eyes for large fields. Peripherally, peak contrast sensitivity remained lower in the amblyopic eyes for all field sizes examined. High spatial frequency cut-offs were reduced both centrally and peripherally with all field sizes in the amblyopic eyes. The effect of increasing field size on the cut-off acuity was found to be smaller than the effect on peak contrast sensitivity. The most significant conclusions drawn from the results are that: (1) The amblyopic deficit in terms of both peak contrast sensitivity and acuity is not restricted to the central foveal region; and (2) amblyopic eyes benefit to a greater extent from increased stimulus field size than non-amblyopic eyes in terms of peak contrast sensitivity. A model is proposed which suggests that the results obtained are due to fewer and/or less sensitive cortical neurons being driven by the amblyopic eye in humans with naturally occurring amblyopia.
本研究的目的是使用对不同视场大小的正弦波光栅的对比度敏感度测量方法，确定在视网膜偏心度为0度、10度和20度时弱视缺陷的程度。结果显示，对比度敏感度函数随刺激视场大小、视网膜位置和弱视程度而变化。在中央凹处，弱视眼的峰值对比度敏感度随视场大小增加而显著提高，对于大视场，其峰值与对侧非弱视眼相同。在周边，在所检查的所有视场大小下，弱视眼的峰值对比度敏感度均较低。弱视眼在中央和周边的高空间频率截止值在所有视场大小下均降低。研究发现，视场大小增加对截止视力的影响小于对峰值对比度敏感度的影响。从结果中得出的最重要结论是：（1）在峰值对比度敏感度和视力方面，弱视缺陷不仅限于中央凹区域；（2）就峰值对比度敏感度而言，弱视眼比非弱视眼从增加的刺激视场大小中获益更大。提出了一个模型，该模型表明所获得的结果是由于在患有自然弱视的人类中，弱视眼驱动的皮质神经元数量减少和/或敏感性降低所致。
