November 1, 2020
By Xiao Nicole Liu, MOptom
PhD Candidate, Brien Holden Vision Institute
In spite of disparities observed across species, there is strong evidence supporting the role of light environment on eye growth and refractive error development.1 For example, while fish, chicks and guinea pigs reared in monochromatic light became more myopic in long-wavelength light (i.e., red or green light) and more hyperopic in short-wavelength light (i.e., blue light), tree shrews and rhesus monkeys showed opposite results: they became more hyperopic in red light and more myopic in blue light.
In humans, outdoor exposure has been well recognized as a protective factor against myopia onset.2 Since indoor lighting rarely contains light under 400 nm, Jiang et al. suggested that lack of violet light (VL) (360 – 400 nm, VL) in artificial lighting environment might be one of the causes of the myopia surge in modern societies.3 Actually, their group has reported a protective effect of VL against myopia in both animals (chicks) and humans.4,5 In a review article published in 2018 they examined the relationship between myopia and light environment and discussed the possibilities of using VL for myopia control.
Using light as a tool for myopia control has generated a considerable amount of interest in myopia research. When talking about light many factors need to be considered, such as intensity and spectral bandwidth of the light, exposure pattern (e.g., duration and rhythmicity of the exposure) and the experiment subjects’ temporal sensitivity. As illustrated by the authors, mechanisms behind any light therapy for myopia control ‘must not be simple,’ and more clinical trials are required to establish concrete, evidence-based guidelines.
To conclude, the authors presented a detailed review of light environments and myopia, proposed a bold idea of using VL to treat myopia, and introduced an intriguing clinical trial to evaluate artificial VL’s effect on myopia control in humans.
Progress and Control of Myopia by Light Environments
Xiaoyan Jiang, Toshihide Kurihara, Hidemasa Torii, Kazuo Tsubota
During the past 30 years, the prevalence rate of myopia has been increased dramatically. Myopia has become one of the leading causes of vision loss in some countries, whereas the mechanism of the main pathological change in myopia is still largely unknown. Although several studies showed genetic background influences the phenotype of myopia to some extent, the sudden increase of morbidity cannot be explained by genetics only. The change in lifestyle results in tremendous change in the light environment, which can be considered to play an important role in the onset and progression of myopia. The difference between indoor and outdoor light environments such as intensity and wavelength of modern electronic lighting equipment may be a cue for myopia control as environmental factors. In this review, we discuss the relationship between myopia and light environment focusing on the basic and clinical studies.
- Rucker F. Monochromatic and white light and the regulation of eye growth. Experimental Eye Research. 2019;184:172-82.
- Xiong SY, Sankaridurg P, Naduvilath T, Zang JJ, Zou HD, Zhu JF, et al. Time spent in outdoor activities in relation to myopia prevention and control: a meta-analysis and systematic review. Acta Ophthalmologica. 2017;95(6):551-66.
- Jiang X, Kurihara T, Torii H, Tsubota K. Progress and Control of Myopia by Light Environments. Eye & contact lens. 2018;44(5):273-8.
- Torii H, Kurihara T, Seko Y, Negishi K, Ohnuma K, Inaba T, et al. Violet Light Exposure Can Be a Preventive Strategy Against Myopia Progression. EBioMedicine. 2017;15:210-9.
- Torii H, Ohnuma K, Kurihara T, Tsubota K, Negishi K. Violet Light Transmission is Related to Myopia Progression in Adult High Myopia. Sci Rep. 2017;7(1):14523.