Title: The Epidemic of Myopia: Prospects for Prevention
Author: Ian Morgan
Affiliation: Research School of Biology, Australian National University, Canberra, Australia.
In the developed countries of East and Southeast Asia, myopia has now reached epidemic proportions. In young adults, the prevalence of myopia is 80-90%, while that of high myopia is 10-20%. The increased prevalence of high myopia seems to result from the increasingly early onset of myopia and the faster rates at which myopia worsens during childhood years that have occurred during the emergence of the epidemic. A major risk factor for myopia is education, perhaps mediated by the amount of near-work children perform. In addition, reduced time spent outdoors by children also promotes the development of myopia. The mechanism for the first effect may involve regulation of eye growth by defocus signals generated in the retina, while the latter effect appears due to the regulation of retinal dopamine release by light outdoors. Increased time outdoors in schools has been shown to reduce new cases of myopia. In addition, it is possible to clinically control the rate of worsening of myopia by using atropine eye-drops or orthokeratology. Systemic application of these control measures is expected to reduce the prevalence of myopia and high myopia, thus reducing the risk of vision loss due to pathological changes associated with high myopia.
Title: Light-Induced Dopamine Release Prevents the Development of Experimental Myopia
Author: Regan Ashby
Affiliation: Health Research Institute, Faculty of Education, Science, Technology and Mathematics, University of Canberra, Canberra, Australia.
Recently, epidemiological studies have shown a clear negative correlation between time spent outdoors and the development of myopia in children, with a number of successful clinical trials already published. It has been postulated that such a protective effect might be mediated by the light-stimulated release of dopamine from the retina, which has been supported by findings from animal studies. Specifically, rearing animals under high illumination levels, relative to that normally seen indoors, significantly retards the development of deprivation-myopia in chicks, rhesus monkeys, tree shrews and mice. In chicks this protective effect is abolished by the administration of the D2 receptor antagonist Spiperone, indicating light dopamine release and D2 dopamine receptors as critical in the pathway. Importantly, in chicks, high light not only prevents the onset of deprivation-myopia but it also halts further progression in already myopic eyes. One of the critical implications of these findings is that manipulation of the dopaminergic system can be used to prevent the development of myopia.
Title: A Novel Wearable Device to Quantify Myopia-Related Behavior Pattern: Analysis of the Data
Author: Weizhong Lan
Affiliation: Aier Institute of Optometry and Vision Science/ Aier School of Ophthalmology, Aier Eye Hospital Group, Hunan, China
The prevalence of myopia has been increasing steeply in the last decades. However, the underlying pathogenesis is still unclear. Although excessive near-work and lack of outdoor exposure have been generally accepted as myopia-related behaviors, the quantitative correlation between them are inconsistent. One of the major reasons is that conventional approaches (e.g., questionnaire and diary) could only provide overall period-based data (e.g., at most daily), which are not without memory bias. In this presentation, I am going to introduce a novel wearable device that can measure myopia-related behaviors objectively and dynamically. Other than a precise evaluation of the total dose, the device can therefore provide the temporal pattern of these behaviors as well, which was recently found to be a critical independent factor influencing the biological effect. In addition, we have developed an algorithm to describe the myopia-related behaviors, using large data analysis. In a pilot study consisting of 43 students, it is shown that distinct visual behavior patterns exist among students even in the same classroom. It is believed that the technique could offer new insight into the myopia epidemic.
Title: Successful attempts to prevent myopia in Taiwan
Author: Pei-Chang Wu
Affiliation: Department of Ophthalmology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan.
The Taiwan Student Vision Care Program (TSVCP) promoted by the Ministry of Education has been in effect for 3 decades in Taiwan. During that time myopia prevalence steadily increased to a high level and therefore research into myopia prevention was given high priority as an important goal of the program. However, in the absence of an evidence-based protective factor, the rise of myopia continued despite much effort to curb it. When it was discovered that the time spent outdoors was an important factor for myopia protection, it was promptly implemented in TSVCP, leading to a breakthrough during the last 4 years. A nationwide visual acuity screening of elementary school pupils showed that the previously declining vision score (based on uncorrected visual acuity of 20/25 or less) was stopped and reversed. This result strongly supports the "myopia prevention by increased outdoor activities" strategy within TSVCP.