近视与光照的关系

近视的发病率逐年上升且有低龄化趋势，减少近视发生、控制近视度数增长一直是近视防控领域的研究热点。有随机临床对照试验发现户外活动可以有效降低发病率，延缓近视度数加深；基础实验也证实光照与近视的发生发展存在一定的关系。本文对光照与近视的研究进展、局限性和未来发展方向进行了综述。从光照性质来看，增加光照强度能够减缓近视进展，减少实验性诱导近视的产生，但具体的作用机制尚不清楚。光照的明/暗周期节律性变化会造成褪黑素和多巴胺的分泌异常，眼压以及脉络膜厚度昼夜节律性的改变，从而对近视造成影响。此外，波长较长的红光成像在视网膜后，更易诱导近视产生，而中短波长的蓝光成像在视网膜之前，能够延缓近视进展。但不同物种对于不同波长光的反应不同，光波长与近视的关系还有待进一步研究。将来的研究可深入探索光照改变近视进展的作用机制，包括光照如何改变多巴胺的水平，引起下游信号通路的改变，从而控制眼轴长度的生长，以及视网膜感光细胞如何接收到不同波长光的信号，从而调节眼部屈光度，以设计合理的人工照明光照强度、组成成分和性质，并将其用于近视防控。

Relationship between Myopia and Light Exposure

Epidemiological studies found that the incidence of myopia was increasing year by year and the age of onset of myopia was showing a trend of affecting increasingly younger children. Reducing the occurrence of myopia and controlling the increase of myopia diopter have always been the focus of research on the prevention and control of myopia. Large randomized controlled clinical trials have found that outdoor activities can effectively reduce the incidence of myopia and delay the progression of myopia. Basic experiments also revealed that there were certain connections between light exposure and myopia. We herein review the research progress, limitations and future directions of research on light exposure and myopia. From the perspective of light properties, increasing the intensity of light can slow the progression of myopia and reduce the occurrence of experimentally induced myopia. However, the actual mechanism of action is still unclear. The rhythmic changes of light exposure caused by the light/dark cycle may cause abnormalities in the secretion of melatonin and dopamine, and changes in the circadian rhythm of intraocular pressure and choroidal thickness, thus affecting myopia. The red light, with relatively longer wavelength and forming images behind the retina, tends to induce myopia more easily, while the blue light, with medium and short wavelength and forming images before the retina, tends to delay myopia progression. However, different species respond differently to lights of different wavelengths, and the relationship between light wavelength and myopia needs further investigation. Future research can be done to further explore the mechanism of action of how light exposure changes the progression of myopia, including the following aspects: how light changes dopamine levels, causing changes in downstream signal pathways, and thus controlling the growth of the axial length of the eye; how retinal photoreceptor cells receive light signals of different wavelengths in order to adjust the refractive power of the eyes; and how to design artificial lighting of reasonable intensity, composition and properties, and apply the design in myopia prevention and control.