A massive new study by a consortium of researchers offers the most detailed view yet of the role genetics plays in nearsightedness.
This is most extensive study of on nearsightedness to date, and it identified dozens of loci, and more than 8,000 variants, associated with the condition. The study included data from more than 160,000 people of different ancestries, which allowed the researchers to find genetic variants associated with nearsightedness, also known as myopia, in both people of European and Asian ancestry.
“Our list of plausible genes and pathways provides a plethora of data for future studies focusing on gene-environment interaction and on translation of GWAS findings into starting points for therapy,” according to the study authors.
For their work the researchers from several dozen institutions but lead by scientists at Johns Hopkins and others from the International Consortium for Refractive Error and Myopia (known as CREAM), conducted what is called a meta-analysis, combining data from several different other studies. This included data from more than 100,000 23andMe customers who consented to participate in research. CREAM provided data from about 50,000 people for the study.
The researchers were also able to use the findings to identify some biological pathways for developing myopia.
But even though genetics plays a role, lifestyle and environmental factors explain the substantial increase in the number of people with myopia.
It turns out we’re in the middle of a myopia epidemic particularly in urban areas of East Asia, where for example as many as 95 percent of 20 year-olds in cities like Hong Kong or Seoul are nearsighted. In the United States and Western Europe, the numbers are not quite so high, but much higher than they were a generation ago, now as many as half of young adults are nearsighted. In the 1970s it was only about a quarter of young adults.
The reason for the big increase is mostly related to changes in lifestyle — more people spending time indoors, changes in diet, and, in recent years, spending hours each day in front of computer screen or staring at a smartphone. Diet also plays a role, and several studies have shown that a diet high in leafy greens can help reduce the risk, as can more time outdoors.
This study may help researchers learn more about how the interplay of genetics and lifestyle and environment lead to myopia, which occurs when the eye grows too long from front to back. This, in turn, leads to what is called “refractive error,” which means that the shape of your eye doesn’t allow it to bend light correctly which results in a blurred image. This change in the shape of your eye makes it harder for the light-sensitive tissue in the back of the eye to focus on an image. Instead, images are focused toward the front of the eye where the retina is, that is why people with myopia might see things close up just fine, but have a hard time focusing on objects in the distance.
This new genetic study can help in garnering more insight into how myopia develops as well as potential drug targets for treating the condition.