Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.
Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada.
Invest Ophthalmol Vis Sci. 2018 Mar 1;59(3):1467-1474. doi: 10.1167/iovs.17-23526.
To develop an objective psychophysical method to quantify light-induced visual discomfort, and to measure the effects of viewing condition and stimulus wavelength.
Eleven visually normal subjects participated in the study. Their pupils were dilated (2.5% phenylephrine) before the experiment. A Ganzfeld system presented either red (1.5, 19.1, 38.2, 57.3, 76.3, 152.7, 305.3 cd/m2) or blue (1.4, 7.1, 14.3, 28.6, 42.9, 57.1, 71.4 cd/m2) randomized light intensities (1 s each) in four blocks. Constant white-light stimuli (3 cd/m2, 4 s duration) were interleaved with the chromatic trials. Participants reported each stimulus as either "uncomfortably bright" or "not uncomfortably bright." The experiment was done binocularly and monocularly in separate sessions, and the order of color/viewing condition sequence was randomized across participants. The proportion of "uncomfortable" responses was used to generate individual psychometric functions, from which 50% discomfort thresholds were calculated.
Light-induced discomfort was higher under blue compared with red light stimulation, both during binocular (t(10) = 3.58, P < 0.01) and monocular viewing (t(10) = 3.15, P = 0.01). There was also a significant difference in discomfort between viewing conditions, with binocular viewing inducing more discomfort than monocular viewing for blue (P < 0.001), but not for red light stimulation.
The light-induced discomfort characteristics reported here are consistent with features of the melanopsin-containing intrinsically photosensitive retinal ganglion cell light irradiance pathway, which may mediate photophobia, a prominent feature in many clinical disorders. This is the first psychometric assessment designed around melanopsin spectral properties that can be customized further to assess photophobia in different clinical populations.
开发一种客观的心理物理方法来量化光诱导的视觉不适，并测量观察条件和刺激波长的影响。
11 名视力正常的受试者参与了这项研究。实验前，他们的瞳孔被扩瞳（2.5%苯肾上腺素）。一个全视野系统呈现红色（1.5、19.1、38.2、57.3、76.3、152.7、305.3 cd/m2）或蓝色（1.4、7.1、14.3、28.6、42.9、57.1、71.4 cd/m2）随机强度的光（持续时间 1 秒），分为四组。恒定的白光刺激（3 cd/m2，持续时间 4 秒）与彩色试验交替进行。参与者报告每个刺激是“不舒服地亮”还是“不不舒服地亮”。实验是在双眼和单眼分别进行的，在不同的会话中，颜色/观察条件的顺序是随机的，参与者之间的顺序是随机的。使用“不舒服”的反应比例来生成个体心理物理函数，从中计算出 50%不适感阈值。
与红光刺激相比，蓝光刺激下的光诱导不适更高，无论是在双眼（t(10) = 3.58，P < 0.01）还是单眼观察（t(10) = 3.15，P = 0.01）时。在观察条件之间也存在不适感的显著差异，与单眼观察相比，双眼观察诱导的蓝光刺激下的不适感更多（P < 0.001），但红光刺激则不然。
这里报告的光诱导不适特征与包含黑视蛋白的光感受器内在光敏视网膜神经节细胞光辐照度途径的特征一致，该途径可能介导畏光，这是许多临床疾病的一个突出特征。这是第一个围绕黑视蛋白光谱特性设计的心理物理评估，可以进一步定制，以评估不同临床人群的畏光。
