Vision Science Laboratory, University of Georgia, Athens, Georgia.
Invest Ophthalmol Vis Sci. 2013 Sep 19;54(9):6298-306. doi: 10.1167/iovs.13-12365.
To compare action spectra for visual discomfort in the fovea and the parafovea and to determine the effect of macular pigment (MP).
Visual discomfort thresholds to lights from 440 to 600 nm were obtained for six young (<35 y), visually normal subjects with a wide range of MP densities (0.10-0.71 at 30' eccentricity). Foveal and parafoveal conditions were assessed. Discomfort thresholds were also obtained for xenon-white light (partially absorbed by MP), and a broadband yellow (outside the absorption band of MP). MP was measured psychophysically using heterochromatic flicker photometry (HFP).
For the parafovea, discomfort sensitivity (1/threshold) increased sharply with decreasing wavelength for all subjects. Commensurate with a subject's MP level, MP significantly reduced visual discomfort to short wavelengths (including xenon-white light) for central viewing.
MP simultaneously reduces visual discomfort and protects from light damage at short wavelengths. As a result, MP increases the range of safe and comfortable light levels. Because higher light levels enable improved visual sensitivity for fine detail, these findings indicate that the spectral absorption properties and spatial distribution of MP combine to protect the retina while enhancing visual performance. The action spectrum for visual discomfort closely matches the risk for acute light damage to the retinal pigment epithelium, and it is consistent with a major influence from the intrinsically photosensitive retinal ganglion cells containing melanopsin. We suggest that MP interacts with nonimage-forming retinal input to achieve the dual outcomes of visual discomfort reduction and protection from light damage.
比较黄斑和旁黄斑视觉不适的作用光谱，并确定黄斑色素（MP）的作用。
使用宽范围 MP 密度（30' 偏心度处为 0.10-0.71）的六名年轻（<35 岁）、视力正常的受试者，获得了 440 至 600nm 光的黄斑和旁黄斑视觉不适阈值。评估了中央凹和旁黄斑条件。还获得了氙白光源（部分被 MP 吸收）和宽带黄光（在 MP 吸收带之外）的不适阈值。使用异相闪烁光度法（HFP）对 MP 进行了心理物理学测量。
对于旁黄斑，所有受试者的不适敏感性（1/阈值）随着波长的降低而急剧增加。与受试者的 MP 水平相称，MP 显著降低了中央注视时短波长（包括氙白光源）的视觉不适。
MP 同时降低了短波长的视觉不适和光损伤风险。因此，MP 增加了安全和舒适的光照水平范围。由于更高的光照水平能够提高对精细细节的视觉灵敏度，这些发现表明 MP 的光谱吸收特性和空间分布结合起来，在提高视觉性能的同时保护视网膜。视觉不适的作用光谱与视网膜色素上皮急性光损伤的风险密切相关，与包含黑视素的光敏感视网膜神经节细胞的主要影响一致。我们认为，MP 与非图像形成的视网膜输入相互作用，以实现降低视觉不适和保护免受光损伤的双重效果。
