In order for your vision to be clear, the light must reflect on the object you are looking at and pass through your eye to focus at a point on the surface of your retina.
The main visual defects come from the fact that the light does not focus in the right place on the retina.
This visual impairment occurs most often when the eyeball is too long or the cornea is too curved, meaning the distance between the cornea and the retina is too great. A myopic patient can see close-up objects clearly, but not distant objects because the image is formed in front of the retina, rather than directly on its surface.
Myopia typically begins in childhood and progresses into adulthood, at which point it stabilises, at the age of around 20-25 years old.
In children, squinting the eyes to look in the distance, or moving closer to objects when writing, drawing or reading, are revealing signs.
A child whose parents are short-sighted is more likely to develop myopia in turn.
The chances of developing myopia are also increased by lack of exposure to sunlight.
This visual impairment occurs most often when the eyeball is too short or the cornea is insufficiently curved, meaning the image is formed behind the retina and requires a permanent effort of focusing in far vision but even more so in near vision. Unlike a short-sighted individual, a long-sighted individual struggles to focus on close-up objects but can often see quite clearly into the distance.
Although much less common than myopia, this ocular defect can also be accompanied by headaches and visual fatigue.
People are often long-sighted without knowing it... and most people do not realise that they have hyperopia until they are in their thirties!
In young people, hyperopia is not corrected in the absence of symptoms, and is actually very common in young children. It will only be corrected if it is severe or accompanied by strabismus.
Symptoms can occur in teenagers and young adults who spend a lot of time reading or working at a computer: a correction is therefore necessary.
Astigmatism is due to an abnormality in the curvature of the cornea or lens, which instead of having the spherical shape of a tennis ball is more like that of a rugby ball.
The light can no longer focus on the retina and the image is blurred up-close and in the distance.
Astigmatism disrupts near vision and distance vision and is often associated with myopia or hyperopia.
People with astigmatism encounter difficulties in distinguishing contrasts between horizontal, vertical or oblique lines, which causes them to confuse similar letters like H and M, and numbers 8 and 0 etc.
Uncorrected, astigmatism can cause eye strain and headaches.
Presbyopia is a natural age-related process that usually develops in your forties. The lens loses its flexibility and ability to focus on nearby objects.
Presbyopia is characterised by difficulties in reading small print with the need to move the text farther from the eyes to see it more clearly, and to improve the lighting etc. These initial symptoms can be accompanied by headaches and visual fatigue.
Young people with presbyopia often delay the management of their visual deficit and tire unnecessarily. As presbyopia evolves physiologically and increases with age: it is better to compensate for it at the sign to preserve your visual comfort.
Whatever the visual impairment,
DRL night lenses from the Precilens laboratory
are most often recognised as the most effective solution to slow and correct myopia with or without astigmatism, and hyperopia with our without astigmatism, whether or not associated with the beginnings of presbyopia.