12 Oct You may soon not need glasses
A study of gene changes in the retina has brought closer the day when drugs may be able to stop
or reverse the development of nearsightedness, or myopia, a common condition expected to
affect half the world’s population by 2050.
Dr. Andrei Tkatchenko, of Columbia University in New York City, NY, led a study that found
that, for the most part, the development of myopia and hyperopia, or farsightedness, involves
different genes and cell signaling pathways.
Prior to this, specialists typically assumed that “opposite changes in the same genes and
pathways” determined how the two eye conditions developed after birth, note the authors in a
paper on their work that now features in the journal PLOS Biology.
However, their findings contravene the traditional view: they offer an alternative understanding
of myopia and “a framework for the development of new antimyopia drugs.”
Myopia impairs distance vision but not near vision; it usually develops because the eye grows
Those with hyperopia experience the opposite: their eye is too short, causing it to focus images
behind the retina.
This generally results in distant objects being clearer than near ones, but in some cases, it can
result in everything looking blurred.
There is evidence that both genes and environmental factors, such as spending less time outdoors
and more time indoors reading and using computers, can increase the risk of myopia. Before this
study, however, it was not clear what the underlying molecular mechanisms were.
One way to observe the biological development of myopia or hyperopia is by altering the focal
length of the eye in laboratory animals. Specialists can do this by placing a lens in front of the
eye for several weeks.
Depending on the type of lens, the exposure causes the eye to develop to a length that is either
too long or too short.
The scientists used this method in marmosets to study the development of myopia and hyperopia.
They placed a lens in front of only one eye for up to 5 weeks and let the other eye develop
normally for comparison.
Upon examining each animal’s two retinas after the exposure time, the team revealed differences
in gene expression between the exposed and the unexposed eye.
A comparison between those that had an eye that developed myopia and those that developed
hyperopia, however, showed that the conditions were the result of “activation or suppression of
largely distinct pathways.”
The researchers also found that 29 of the genes that changed expression were in the same
chromosome regions that large genetic studies have linked to myopia in humans.
“Identification of these pathways provides a framework for the identification of new drug targets
and for the development of more effective treatment options for myopia.”