Werner J S, Bieber M L, Schefrin B E
Department of Ophthalmology, University of California, Davis Medical Center, Sacramento 95817, USA.
J Opt Soc Am A Opt Image Sci Vis. 2000 Nov;17(11):1918-32. doi: 10.1364/josaa.17.001918.
Foveal and parafoveal increment thresholds were measured for 50 observers (12-88 years of age) under conditions that isolated retinal mechanisms dominated by short- (S-), middle- (M-), or long- (L-) wave-sensitive cones. Thresholds were obtained on the plateau of the threshold-versus-intensity function of each isolated mechanism and were referred to the retina by using individual measurements of ocular media and macular pigment density. Age-related increases in foveal thresholds, specified at the retina, were found for all three cone mechanisms. Parallel sensitivity losses for each cone mechanism were also observed at 4 degrees and 8 degrees in the temporal retina. A significant positive correlation was found between foveal macular pigment density and the S-cone, but not the M- and L-cone, log sensitivity difference (0 degrees-8 degrees) specified at the retina. This relation is expected from the hypothesis that the macular pigment protects the photoreceptors from senescent losses in sensitivity. However, because this result is independent of age, it is interpreted as being due to local gain changes resulting from differential filtering of incident light by the macular pigment between the fovea and the parafovea.
在分离出由短波（S）、中波（M）或长波（L）敏感视锥细胞主导的视网膜机制的条件下，测量了50名观察者（年龄在12至88岁之间）的中央凹和中央凹旁增量阈值。阈值是在每种分离机制的阈值与强度函数的平稳段获得的，并通过对眼介质和黄斑色素密度的个体测量将其与视网膜相关联。对于所有三种视锥细胞机制，都发现了视网膜上中央凹阈值随年龄的增加。在颞侧视网膜4度和8度处也观察到每种视锥细胞机制的平行敏感性损失。发现视网膜上中央凹黄斑色素密度与S视锥细胞之间存在显著正相关，但与M视锥细胞和L视锥细胞的对数敏感性差异（0度至8度）不存在显著正相关。从黄斑色素保护光感受器免受衰老性敏感性损失的假设可以预期到这种关系。然而，由于这一结果与年龄无关，因此被解释为是由于黄斑色素在中央凹和中央凹旁对入射光的差异过滤导致的局部增益变化。
