Mac Cana F, Cuthbert A, Lovegrove W
Vision Res. 1986;26(5):781-9. doi: 10.1016/0042-6989(86)90093-3.
Contrast-coding was investigated in amblyopic, fellow non-amblyopic and control eyes. Using a contrast-matching paradigm similar to Georgeson and Sullivan [J. Physiol. 252, 627-656 (1975)], amblyopic eyes were found to have a high frequency contrast-coding deficit not only at threshold but also at suprathreshold levels up to at least 0.45 contrast. The results do not support the claim of Hess and Bradley [Nature 287, 463-464 (1980)] and Hess, Bradley and Piotrowski [Proc. R. Soc. Lond. B217, 309-330 (1983)] that amblyopes have normal or near-to-normal suprathreshold contrast-coding. By taking this contrast-coding deficit into account we demonstrate that previously reported poor phase discrimination [Lawden, Hess and Campbell, Vision Res. 22, 1005-1016 (1982); Pass and Levi, Invest. Ophthal. Visual Sci. 23, 780-786 (1984)] in amblyopia may, in part, reflect a more basic deficit in contrast-coding across spatial frequencies. The possible involvement of contrast processing mechanisms in phase discrimination is discussed.
在弱视眼、健侧非弱视眼和对照眼中研究了对比度编码。采用类似于乔治森和沙利文[《生理学杂志》252, 627 - 656 (1975)]的对比度匹配范式，发现弱视眼不仅在阈值处，而且在高达至少0.45对比度的超阈值水平都存在高频对比度编码缺陷。结果不支持赫斯和布拉德利[《自然》287, 463 - 464 (1980)]以及赫斯、布拉德利和皮奥特罗夫斯基[《伦敦皇家学会学报》B217, 309 - 330 (1983)]的观点，即弱视患者具有正常或接近正常的超阈值对比度编码。通过考虑这种对比度编码缺陷，我们证明了先前报道的弱视患者较差的相位辨别能力[劳登、赫斯和坎贝尔，《视觉研究》22, 1005 - 1016 (1982); 帕斯和利维，《眼科与视觉科学研究》23, 780 - 786 (1984)]可能部分反映了跨空间频率的对比度编码中更基本的缺陷。讨论了对比度处理机制在相位辨别中的可能作用。
