What are the main causes of myopia? Why are we myopic?

In the vast majority of cases, myopia is due to an eye that is too long. It is important to know that when you look at something, the image of the object is supposed to be formed on the retina. In a myopic person, the image is formed in front of the retina. As a result, the brain receives a blurred image of distant objects. In some rare cases, a deformation of the cornea (overly curved cornea) can be the cause of myopia.

This deformation of the eye can be due to several factors:

Genetics: it has been shown that genetics is one of the causes of myopia. A child whose parents are both myopic is, for example, six times more likely to become myopic. However, if heredity is involved, the exact genetic origin has not yet been determined.
Our environment: studies also show that a lack of exposure to natural light can disrupt the growth of the eye, and thus encourage the development of myopia.
Our lifestyle: our lifestyle, and therefore our vision, is directly involved in the appearance of this visual defect. Researchers have observed an impressive increase in the number of cases of myopia in generations Y and Z. The reason for this is that close-up vision is overused on a daily basis. Among other reasons, the amount of time spent in front of screens (smartphones, tablets, computers, television, etc.) has increased considerably, overtaxing our near vision and consequently favouring the appearance of myopia. This phenomenon can also be observed in students, who generally spend a lot of time working (reading, writing, etc.) in close vision. This phenomenon is called "student myopia".

Ultimately, it is the combination of all these elements that causes myopia. Moreover, it is estimated that by 2050, with the rapid and radical evolution of our lifestyles, half the world's population will be myopic*. In 2000, only a quarter of the world's population was myopic.

Evolution of myopia: how can myopia be stopped? Can myopia be stabilised?

Today, the onset of myopia can be prevented by increasing exposure to outside light. However, it has not been clearly established that this slows down the progression of myopia. The development of myopia also depends on the age of onset. The earlier the onset of myopia, the faster it progresses and reaches high levels. In China, for example, the first myopias appear around the age of five, and these same myopias will stabilise at around -6.00 / -8.00 dioptres, with a pathological risk. Fortunately, this is not the case for everyone.

Myopia and presbyopia: from the age of 40 onwards, do myopic people also become presbyopic?

Presbyopia is linked to the ageing of the lens, regardless of the visual defect. Myopic people who see well at close range can, in certain cases (depending on age and level of myopia), do without their glasses to continue to see clearly at close range... but must quickly put them back on to see clearly at a distance. Progressive lenses are therefore the best solution to avoid these acrobatics and to see clearly at all distances after the age of 40-45, without changing or removing and then putting back on their glasses.

Driving at night: why is it more difficult for me to drive at night?

This is called night myopia. The lack of light, the glare from car headlights and urban lighting, not to mention the difficulty in judging distances (at night, the pupil dilates more and alters the appreciation of the depth of field) make our night vision more awkward and painful.

Myopia in children: how can I tell if my child is myopic?

As early as primary school, or even kindergarten, if a child's parents are myopic, it is recommended that they consult an ophthalmologist in order to identify and correct any myopia without delay. The main symptoms of myopia in children are

Difficulty in reading the blackboard in class.
Failure/discouragement in team sports.
Excessive closeness when drawing or writing.
Squinting of the eyelids to see better.

Whether your child is myopic or not, the most important thing is that he or she spends as little time as possible on the screens: this activity requires a lot of near vision and a great deal of accommodation, which can lead to myopia in the long run. This is also known as student myopia, which will progress rapidly if the myopic person does not take regular breaks (spending time outside in the daylight).

Glasses for the myopic: how should I choose my pair of glasses?

Which glasses should I choose if I am myopic? The best advice for choosing a pair of glasses:

Your myopia is slight, below 1.5 dioptres: there are no restrictions on your choice of frames: drilled, extra-wide, semi-invisible (with a nylon thread at the bottom of the frame), metal or acetate, etc. Do as you please.
You are moderately myopic, up to 6 dioptres: thanks to slimmed lenses, the choice of a frame remains very open to match the style you like. A myopic lens is concave, i.e. thicker at the edges than in the centre, and its thickness increases with the degree of correction. But with a thinned lens, you can reduce its thickness by up to 40%** compared to an ordinary lens. Some frames make it easier to hide this unsightly thickness: a reasonably sized frame will allow the eyecare professional to trim the thickest edge of the optical lens, an acetate frame with thick edges will hide the edge of the lens.
A thinned lens reduces the thickness of the lens, but also the optical effect that makes the eye appear smaller behind the lens. A frame worn very close to the face also helps to reduce this effect.
If you are very short-sighted: a frame with small lenses is recommended and a so-called pierced frame (without a metal or acetate contour) is not recommended.

In any case, ask your eyecare professional for advice to find the best optical (and aesthetic) solution.

*Holden BA, Fricke TR, Wilson DA, et al. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology 2016. **Comparaison de l'épaisseur de deux verres Essilor de même prescription et d'indices différents.