Pardhan Shahina, Whitaker Angela
Department of Optometry and Ophthalmic Dispensing, Anglia Polytechnic University, East Road, Cambridge CB1 1PT, UK.
Curr Eye Res. 2003 May;26(5):297-302. doi: 10.1076/ceyr.26.4.297.15430.
Binocular summation for contrast detection in the fovea is lower in older normal subjects. At present, no binocular summation data exist for contrast detection in older subjects in the peripheral field.
Monocular and binocular contrast thresholds were measured for sine-wave gratings of 1 c/deg (F1) and 4 c/deg (F4) in the fovea in young and older visually normal subjects. Measurements were also obtained at 8 degrees in the superior field for gratings of 1 c/deg (P1) and 4 c/deg (P4).
Binocular summation ratios in young subjects at the fovea and periphery were not statistically different at either spatial frequency. In older subjects, analysis of the relevant conditions showed significantly lower summation ratios for: P4/F4 combination (p = 0.05), and P4/P1 combination (p = 0.03). No significant differences existed for F1/P1 and F1/F4 combinations (p > 0.05).
Lowest binocular summation ratio is shown with older subjects for gratings of 4 c/deg in the periphery (P4). Further analysis suggests the possibility that this is due to a larger relative loss in binocular sensitivity. Data are discussed in terms of selective loss of binocular neurons mediating peripheral sensitivity in the ageing eye.
在正常老年人中，中央凹对比度检测的双眼总和较低。目前，尚无关于老年受试者周边视野对比度检测的双眼总和数据。
测量年轻和老年视力正常受试者中央凹处1 c/度（F1）和4 c/度（F4）正弦波光栅的单眼和双眼对比度阈值。还在上方视野8度处测量了1 c/度（P1）和4 c/度（P4）光栅的对比度阈值。
年轻受试者在中央凹和周边的双眼总和比率在任一空间频率下均无统计学差异。在老年受试者中，对相关条件的分析显示，以下组合的总和比率显著较低：P4/F4组合（p = 0.05）和P4/P1组合（p = 0.03）。F1/P1和F1/F4组合无显著差异（p > 0.05）。
老年受试者在周边4 c/度（P4）光栅的双眼总和比率最低。进一步分析表明，这可能是由于双眼敏感性相对损失更大。根据介导衰老眼中周边敏感性的双眼神经元的选择性损失对数据进行了讨论。
