Myopia results from excessive growth of the eye, most often during childhood and adolescence. Two groups of factors contribute: genetics, which we cannot choose, and the environment, which can be influenced, especially in children.
Key points
- Having one or two short-sighted parents increases the risk.
- Time spent outdoors in daylight is associated with a lower risk in children.
- Prolonged near work without breaks is a risk factor.
- Myopia that starts early is more likely to become high.
Heredity
Children whose parents are short-sighted have a clearly higher risk of becoming so, especially if both parents are. Many genes involved in eye growth have been identified. Genetics alone, however, cannot explain the rapid rise of myopia seen within a few decades.
Lifestyle: near vision and daylight
Studies in children show two trends:
- prolonged near work (reading, homework, screens), especially at short distance and without breaks, is associated with more myopia;
- time spent outdoors is associated with less myopia. Natural light, much brighter than indoor light, appears to slow eye elongation. School-based trials observed fewer new cases when children spent more time outside.
Good to know
These measures aim to limit the onset and progression of myopia in children. They do not make existing myopia disappear.
Other factors
Age of onset matters: myopia that begins before age 10 generally progresses for longer. Some rare genetic or eye diseases are also associated with myopia, which an eye examination can look for. In adults, myopia that appears or increases late in life should prompt a check of the lens (early cataract) or the cornea.
What you can do every day
- Encourage outdoor activities, around two hours a day for children;
- take regular breaks during near work, for example looking into the distance for a few seconds every 20 minutes;
- keep a sufficient reading distance and good lighting;
- have the eyes of a child with short-sighted parents examined, or of a child who squints to see far away.
Further reading
Frequently asked questions
There is a strong family component: a child of short-sighted parents is more likely to be short-sighted. But the environment also plays an important role.
Reading in poor light tires the eyes but has not been shown to directly cause myopia. Prolonged near work and lack of time outdoors are the best-documented factors.
Yes, myopia can appear or increase in young adults, particularly with intensive near work. Myopia that appears later in life should prompt a search for another cause, such as an early cataract.
This general information does not replace a consultation: only an eye examination can establish a diagnosis and discuss a suitable treatment.