Tran Thi Ha Chau, Despretz Pascal, Boucart Muriel
Laboratoire de Neurosciences et Pathologies Fonctionnelles, CNRS, Université Lille Nord de France, Lille, France.
Optom Vis Sci. 2012 Apr;89(4):419-25. doi: 10.1097/OPX.0b013e31824c3a21.
To investigate the effect of contrast on scene perception in people with age-related macular degeneration (AMD) and to examine the relationship between task performance and macular function.
Nineteen patients with AMD and visual acuity below 20/50 were compared with 16 normally sighted, age-matched controls. Complete ophthalmologic examination (visual acuity, intraocular pressure measurement, and funduscopy) was performed in both patients and controls. In addition, Pelli-Robson contrast sensitivity, fluorescein angiography, and visual field size were assessed in the AMD study patients. The stimuli were photographs of natural scenes containing or lacking an animal (the target). For each scene, the contrast of the original photograph was divided by 2, 4, and 8 to yield versions with a residual contrast of 50, 25, and 12.5%, respectively. The four levels of contrast were presented randomly and participants were asked to press a key when they saw an animal.
AMD patients exhibited a larger drop in target detection performance with the decrease in contrast than controls. We found a correlation between visual acuity and performance when the contrast was reduced to 50, 25, and 12.5% of the original value but not in the normal contrast condition. There were no correlations between letter contrast sensitivity, visual field lesion size, and performance.
Our results suggest that optimal, stable contrast conditions would facilitate object recognition in everyday life for people with AMD.
研究对比度对年龄相关性黄斑变性（AMD）患者场景感知的影响，并探讨任务表现与黄斑功能之间的关系。
将19名视力低于20/50的AMD患者与16名年龄匹配的正常视力对照者进行比较。对患者和对照者均进行了全面的眼科检查（视力、眼压测量和眼底镜检查）。此外，还对AMD研究患者进行了佩利-罗布森对比敏感度、荧光素血管造影和视野大小评估。刺激物是包含或不包含动物（目标）的自然场景照片。对于每个场景，原始照片的对比度分别除以2、4和8，以产生残余对比度分别为50%、25%和12.5%的版本。四个对比度水平随机呈现，参与者被要求在看到动物时按下一个键。
随着对比度降低，AMD患者的目标检测表现下降幅度大于对照者。我们发现，当对比度降低到原始值的50%、25%和12.5%时，视力与表现之间存在相关性，但在正常对比度条件下则不存在。字母对比敏感度、视野病变大小与表现之间没有相关性。
我们的结果表明，最佳、稳定的对比度条件将有助于AMD患者在日常生活中识别物体。
