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The defects of the vision


An estimated 2.5 billion people have an uncorrected vision problem . Others have been able to correct these defects through optics or surgery. Still others have an eye that has no defect. But with age and the screens that are popping up everywhere, our world is fertile ground for vision blemishes.

If the fight against myopia and other impairments is in full swing, we are entitled to ask a multitude of questions: what are the most common vision defects? Does our daily life play a role in these flaws? Surgery today makes it possible to render a normal sight to a shortsighted person, but can it restore sight? If our eye has no defect, can we imagine that one day, we can make it superior?

The opportunity to make a global point on the problems of the vision .

defects- Vision5 @Pixabay [/ caption]

Four main defects of vision

The eye is an amazing organ , working like a camera (or rather a camera). Indeed, like the lens of a lens, the cornea receives light . The lens takes the role of zoom, adjusting the focal length according to the element we focus on.

The pupil will act as a diaphragm to modulate the amount of light that the retina receives , allowing the brain to receive a clear image.

Without even realizing it, because we're used to it, because that we manage to do with, or because we do not remember having a better day, our eye begins to dysfunction. Yet, if an effort is needed to adjust one's vision, or if recurring discomfort comes and goes , it is probably a vision defect.

defects- Vision6 @Pixabay [/ caption]

Four of these defects are defined as major . For each of them, phenomena of accommodation (change of shape of the lens to see near or far) are warning signs:

  • Myopia refers to the difficulty of seeing from a distance. The distance between the cornea and the retina is too great. As a result, the image is formed in front of the retina. That's why we squint to see better when we have no correction.
  • Hyperopia is the opposite of myopia. We have difficulties to see up close. This time, the image is formed behind the retina. The phenomenon of accommodation of hypermetropes often causes great visual fatigue, because it forces a lot on the eye.
  • Presbyopia is the loss of elasticity of the lens and therefore its ability to accommodate. As a result, a presbyopic will have difficulty seeing closely as well.
  • Astigmatism results from a defect in the cornea. The shape of the latter becomes oval rather than spherical, resulting in a deformation of elements that tend to be similar (some letters and figures in particular). Again, without correction, the effort of accommodation causes intense visual fatigue.

Transparency issues

To be in perfect working order, an eye must have an appropriate shape and power . But we have seen, it must also be able to pass the light . Always in comparison with a camera, if the lens leaves more or not enough light to enter, one will obtain a very dark photograph.

In a "normal" eye, the cornea , the aqueous humor, the crystalline lens and the vitreous are perfectly transparent . However, they can become opaque, causing other vision problems.

defects- vision7 @Pixabay [/ caption]

The opacification of the lens is well known to the elderly. This is cataract . It can be more or less important. In most cases, this opacification is treated during the operation. In the case of a congenital or over-advanced cataract , surgeons may have to completely remove the lens and replace it with an implant.

In this case, the ability to accommodation of the eye will be null or very weak, causing extreme presbyopia .

Sunlight: the enemy of our eyes

If we tend to be much more reassured during the day than in the middle of the night, we must admit that, when it comes to our eyes, the natural luminosity may be damn dangerous. Because this light contains strong UV rays , and for that, no need to be dazzled.

A cloudy or even greyish or rainy weather will be just as dangerous, especially since, under this kind of weather, we tend not to protect our eyes, especially our pupil.

defects- vision.3 @Pixabay [/ caption]

Yet, 40% of UV rays occur in cloudy weather.

It is therefore the pupil that will adapt to the external luminosity the amount of light that the eye lets pass. To avoid being dazzled, in case of high brightness, the pupil decreases in size, avoiding to improve the sharpness of the vision.

But when the glare is too much, the pupil is not enough to protect the eyes, and that's why we wear sunglasses.

But the solar port is still not enough. Some figures are even alarming:

  • One in two wears sunglasses regularly.
  • 70% of children do not or very little.

It's just as important to note that poor-quality sunglasses can have a dramatic effect on the eye . Not only do they not protect against UV rays, but simple tinted lenses can trick the retina.

Because if they decrease the brightness, the pupil expands and lets more light! These glasses are therefore extremely dangerous, much more than not to wear any correction!

To know more, find our articles on the CE mark , the optical standards , the index E- SPF and wearing solar cells in winter

And surgery in all this?


Thanks to surgery, we can nowadays correct some of the main defects of vision : myopia, hyperopia or even astigmatism can be improved by this way. Surgery reshapes the cornea to improve vision

defects- Vision4 @Pixabay [/ caption]

What about an eye that does not have a defect? Could we still improve the view, making it as piercing as that of a raptor for example?

If the fiction has, on several occasions, allowed us to dream about it, Of course, we have to be measured.

We can not really know what the influence of surgery will be on our visual abilities , but we can already establish that, in the case of a flawless eye, perfection is not far from being achieved

The eye can not solve infinitely small details because it can not solve details whose image on the retina is less than the distance between two sensors . This limit is common to all eyes.

Moreover, these performances must be linked to those of the brain and accommodation can cause, as we have seen, heavy problems. of visual fatigue . Imponderables that, for the time being, may cause major visual and neurological problems to people who do not have any.

There are many defects in vision . Some are due to aging or wear of our visual organ, while others may be our own. In all cases, constant review and correction is more than necessary. It is mandatory.

Faced with very disturbing figures, the race for the correction is launched!