Lan Weizhong, Feldkaemper Marita, Schaeffel Frank
*MD †PhD Zhongshan Ophthalmic Center (WL), State Key Laboratory of Ophthalmology, Sun Yat-sen University, Guangzhou, China; and Section of Neurobiology of the Eye (WL, MF, FS), Center for Ophthalmology, University of Tuebingen, Tuebingen, Germany.
Optom Vis Sci. 2013 Nov;90(11):1199-206. doi: 10.1097/OPX.0000000000000074.
Bright light is a potent inhibitor of myopia development in animal models. Because development of refractive errors has been linked to changes in choroidal thickness, we have studied in chickens whether bright light may exert its effects on myopia also through changes in choroidal thickness.
Three-day-old chickens were exposed to "bright light" (15,000 lux; n = 14) from 10 AM to 4 PM but kept under "normal light" (500 lux) during the remaining time of the light phase for 5 days (total duration of light phase 8 AM to 6 PM). A control group (n = 14) was kept under normal light during the entire light phase. Choroidal thickness was measured in alert, hand-held animals with optical coherence tomography at 10 AM, 4 PM, and 8 PM every day.
Complete data sets were available for 12 chicks in bright light group and nine in normal light group. The striking inter-individual variability in choroidal thickness (coefficient of variance: 23%) made it necessary to normalize changes to the individual baseline thickness of the choroid. During the 6 hours of exposure to bright light, choroidal thickness decreased by -5.2 ± 4.0% (mean ± SEM). By contrast, in the group kept under normal light, choroidal thickness increased by +15.4 ± 4.7% (difference between both groups p = 0.003). After an additional 4 hours, choroidal thickness increased also in the "bright light group" by +17.8 ± 3.5%, while there was little further change (+0.6 ± 4.0%) in the "normal light group" (difference p = 0.004). Finally, the choroid was thicker in the "bright light group" (+7.6 ± 26.0%) than in the "normal light group" (day 5: -18.6 ± 26.9%; difference p = 0.036).
Bright light stimulates choroidal thickening in chickens, although the response is smaller than with experimentally imposed myopic defocus, and it occurs with some time delay. It nevertheless suggests that choroidal thickening is also involved in myopia inhibition by bright light.
在动物模型中，强光可有效抑制近视发展。由于屈光不正的发展与脉络膜厚度的变化有关，我们研究了在鸡中强光是否也可通过脉络膜厚度的变化对近视产生影响。
3日龄雏鸡于上午10点至下午4点暴露于“强光”（15000勒克斯；n = 14）下，但在光照阶段的其余时间保持在“正常光照”（500勒克斯）下，持续5天（光照阶段总时长为上午8点至下午6点）。对照组（n = 14）在整个光照阶段保持在正常光照下。每天上午10点、下午4点和晚上8点，使用光学相干断层扫描技术在清醒、手持状态的动物中测量脉络膜厚度。
强光组有12只雏鸡和正常光照组有9只雏鸡获得了完整数据集。脉络膜厚度存在显著的个体间差异（变异系数：23%），因此有必要将变化值相对于脉络膜的个体基线厚度进行标准化。在暴露于强光的6小时内，脉络膜厚度下降了-5.2±4.0%（平均值±标准误）。相比之下，在保持正常光照的组中，脉络膜厚度增加了+15.4±4.7%（两组间差异p = 0.003）。再过4小时后，“强光组”的脉络膜厚度也增加了+17.8±3.5%，而“正常光照组”几乎没有进一步变化（+0.6±4.0%）（差异p = 0.004）。最后，“强光组”的脉络膜比“正常光照组”更厚（+7.6±26.0%）（第5天：-18.6±26.9%；差异p = 0.036）。
强光可刺激鸡的脉络膜增厚，尽管这种反应比实验性近视性离焦时小，且有一定延迟。然而，这表明脉络膜增厚也参与了强光对近视的抑制作用。
