Is high myopia hereditary?

The mechanics of myopia

In a healthy eye, light enters the lens of the eye and is refracted (bent) onto the retina to form an accurate, sharp image that the brain can decode. In short-sighted people, the refraction doesn’t work properly; the light is bent so that it focuses in front of the retina, creating a blurry image. This happens if the eye is the wrong shape – the eye may be too long, or the cornea might curve at the wrong angle.

Nature and nurture

But developing myopia isn’t purely a case of genetic inheritance. Our living environments play a part in determining whether the genes we carry will actually be triggered. The more we understand about these environmental factors, the more we can do to prevent myopia in future generations. There’s still a lot of work to be done in this area, but there are some factors that do seem to be linked to elongated eyeballs, which can lead to myopia.

Scientists have found that time spent indoors, doing close-up work such as reading, is linked to a higher risk of short-sightedness. That explains the popular stereotype of bookish types and their bottle-top specs, although researchers are as yet unsure whether it’s the lack of daylight or the close-up work that is more of a factor. In any case, this is a risk factor that can be minimised in early childhood: “Send your kids to play outside for two hours every day,” advises Professor Norbert Pfeiffer, co-author of the CREAM study.