May 2016

 

REFRACTIVE SURGERY

 

Refractive editors corner of the world

Study predicts 50% of the global population will be myopic by 2050


by Liz Hillman EyeWorld Staff Writer

 
 

Steven Schallhorn, MD

Consider this prediction: 4.758 billion peoplenearly 50% of the world populationcould be myopic by the year 2050. Thats a pretty staggering number. In this months Refractive editors corner of the world, we look at a meta- analysis in Ophthalmology that included 145 studies published since 1995. The study authors track an upward trend in the next 4 decades in the rate of myopia at a global scale. While technological advancement has improved many aspects of daily life for people around the world, 1 of the most significant environmental factors driving a more myopic population is a lifestyle that is primarily indoors. Previous studies have established that increasing time outdoors can help reduce incidence of myopia. This months column speaks with 1 of the study co-authors about the research and also brings in refractive experts to comment on the state of myopia in their own countries and what they think could be done from a prevention standpoint.

Steven Schallhorn, MD, refractive editor

 
A more practical tactic is to focus on preventative things to minimize the chance of myopic patients [becoming] highly myopic, and especially the prevention of myopia-related complications. Zheng Wang, MD

conversion of myopic patients

Upward trend of myopia attributed to environmental causes

Kovin Naidoo, OD, PhD, CEO of the Brien Holden Vision Institute, Sydney, Australia, had a sense that the incidence rate of myopia was on the rise. When researchers at the institute conducted a systematic review of the available data on myopia rates and performed meta-analysis, Dr. Naidoo admitted that he did not expect the numbers to come out as high as they did. The paper published in Ophthalmology predicts that by 2050, nearly 50% of the worlds population will be myopic, and almost 10% of these people will be considered highly myopic.1 Myopia, Dr. Naidoo said, is 1 of the biggest public health challenges of our time. The research included 145 studies published since 1995, comprising 2.1 million people total. Conducting meta-analysis, the researchers then made projections for myopia rates each decade for the next 30 years. While myopic patients in 2010 comprised about 28.3% of the global population (1.950 billion people), the study authors predict 49.8% of the world population (4.758 billion people) will be nearsighted by 2050. One billion of them will be considered highly myopic. The study authors cite environmental factors (nurture), principally lifestyle changes resulting from a combination of decreased time outdoors and increased near work activities, among other factors as the primary cause of this upward trend. More specifically, cultures more focused on computer screens and smartphones or those that put more pressure on education at a young age could be driving some of this. Considering these figures, Dr. Naidoo said the lack of discussion among eye health professionals surrounding myopia rates and interventions needed to reverse them is frightening. Dr. Naidoo said practitioners have a responsibility to increase awareness about this trend and about interventions that could help prevent some level of myopia, including encouraging time outdoors for children. A widely circulated study published in the Journal of the American Medical Association in 2015 found that 40 extra minutes of outdoor activity at school reduced myopia incidence rates over 3 years in 6-year-old Chinese children.2

We are definitely arguing that prevention is great, but we are realistic in that were not going to prevent all myopia from occurring just by sending kids outdoors, so there needs to be appropriate correction, there needs to be appropriate intervention, Dr. Naidoo said. As for the increased incidence rates for high myopes, Dr. Naidoo pointed out that prevention and myopia control are key for curbing additional ocular complications, such as blindness, cataracts, glaucoma, and myopic macular degeneration.

I think myopia is going to create new impetus for research into treatment of retinal conditions, particularly myopic macular degeneration, he said. Dr. Naidoo said further studies should include more research on the mechanism behind time spend outdoors and myopia prevention as well as gain more country-specific data on incidence rates. At the end of the day, much of the planning that happens around eyecare doesnt happen at the global level, it happens at the country level, he said, explaining that while this study makes global projections, the issue of myopia might not hit home until more specific data for each country is obtained. While Zheng Wang, MD, director of the Aier Eye Hospital, Guangzhou, China, said there is no exact number on the prevalence of myopia in China, everyone agrees that its higher than the global average, and it has been rising in the past decades. As a matter of fact, very few high school students are not myopic nowadays, Dr. Wang added, saying that, like the study authors, he thinks environmental conditions are the main factor in this trend. Sri Ganesh, MD, said that in his more than 2 decades in practice in India, he has watched myopia numbers increase steadily as well. Our environment is changing, and [people] are glued to display units like laptops, tablets, computer screens, and [myopia] is a kind of adaptation because of the increased accommodation and the need for more near vision, Dr. Ganesh said. Dr. Wang said the growing problem of myopia in China is common knowledge, yet few real effective measures are taken by the government to reduce the burden of students in school, Dr. Wang said. A more practical tactic, I think, is to focus on preventative things to minimize the chance of myopic patients [becoming] highly myopic, and especially the prevention of myopia-related complications. This trend in myopia does present an opportunity for ophthalmologists as refractive surgeries continue to become safer and more effective, Dr. Wang said.

In addition to corneal approaches, intraocular procedures will be accepted by more and more surgeons and patients, he said. Dr. Ganesh pushed those in the field to focus more on prevention of myopia, where possible, in addition to creating treatment plans. Not only as an ophthalmologist but as a doctor, I think that we should look at the community as a whole, he said. Dr. Ganesh is already involved in counseling parents and children in school about making lifestyle changes and understanding the genetic risk factors for myopia. If you look at the community as a whole, I think the preventative aspect is also very important, and I think thats where practitioners should play a role.

References

1. Holden BA, et al. Global prevalence of myopia and high myopia and temporal trends from 2000 through 2050. Ophthalmology. 2016 Feb 11. [Epub ahead of print].

2. He M, et al. Effect of time spent outdoors at school on the development of myopia among children in China: A randomized clinical trial. JAMA. 2015;314:11428.

Editors note: Drs. Naidoo, Wang, and Ganesh have no financial interests related to their comments.

Contact information

Ganesh: chairman@nethradhama.org
Naidoo: K.Naidoo@brienholdenvision.org
Wang: gzstwang@gmail.com

Half of the global population will be myopic by 2050 Half of the global population will be myopic by 2050
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