Magazine article Science News

Clearing Up Blurry Vision: Scientists Gaze toward Causes of Myopia

Magazine article Science News

Clearing Up Blurry Vision: Scientists Gaze toward Causes of Myopia

Article excerpt

Next time you can't make out a distant highway sign, blame your parents. Scientists in the United Kingdom have found that myopia, or nearsightedness, is predominantly hereditary, and they're beginning to unravel the genetic mechanism that causes the vision problem.

Roughly a third of people in the United States suffer from myopia--They clearly see close objects, such as words in a book, but things in the distance appear blurry. The anatomic root of the problem is an elongation of the eye as it grows, causing incoming light to focus in front of the retina, instead of squarely on it, explains Christopher J. Hammond

of St. Thomas' Hospital in London.

Using a noninvasive technique, Hammond measured the sizes of the eyeballs of 280 sets of fraternal adult twins and 226 sets of identical twins. By mathematically modeling the differences in the eye sizes, Hammond found that genes accounted for 89 percent of nearsightedness, farsightedness, and other refractive vision problems, he reports in the July American Journal of Human Genetics.

To investigate what regions of DNA in the general population might have a connection to myopia, Hammond scanned the entire genome of the fraternal twins and found four sections linked to the eye problem. The most strongly linked segment contains 44 genes, including one specified as PAX6, which is already well-known to vision researchers. From fruit flies to humans, this gene is fundamental to eye growth in nearly all species that scientists have examined. …

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