Ametropia is defined by the absence of sharpness in the vision of the eye. It is closely linked to the lack of convergence of the light beams on the retina, with myopia, hyperopia, or even presbyopia as a cause.

The causes of ametropia are usually deformities of the eye and its internal components, related to deformities or aging rather than disease. The role of the eye is indeed to achieve the convergence of light rays coming from the objects around us in a focal point. When everything is perfect, we talk aboutemmetropia. ÀWỌN 'ametropia therefore designates a deviation of light rays.

This deviation is linked to two parameters. On the one hand, the deflection of light rays, effected by the oju eegun ati okuta, two biconvex lenses. On the other, the depth of the eye socket. The whole objective is to focus the rays directly on the retina, on its most sensitive point called the macula, for this, it is necessary to correctly deflect the input beam, and to have the retina at a good distance.

The different causes of ametropia are therefore deformations of the lens, cornea, or depth of the eyeball.

There are different symptoms ofametropia, for each case of discrepancy. Each of them can be accompanied by other symptoms related to impaired vision: headache, eye strain, heavy eye strain.

• Blurred vision from afar: la myopia

If the lens of the eye focuses the light rays too early, as a result of a power ofibugbe too large, or the eye is too deep, we speak of myopia. In this scenario, the nearsighted eye will never really see clearly from a distance, since the rays of distant objects will be focused too soon. Their image will therefore be blurred on the retina.

• Blurred near vision: awọnhyperopia

If the lens of the eye focuses the light rays too late, or the eye is not deep enough, it is called a hyperopic eye. This time, far vision can be performed with a slight accommodation of the lens, in order to focus the rays on the retina. On the other hand, objects that are closer will not be able to focus on the retina. The focal point will therefore be behind the eye, and again the image on the retina will be blurred.

• Vision blurred with age: La presbyopia

As a result of the natural aging of the eye, the okuta, responsible for the accommodation of the eye and therefore for the sharpness of vision, will gradually lose its elasticity and harden. It will therefore be more difficult, if not impossible, to make an image clear if it is too close. This is why most often the first sign of presbyopia is to “reach out” to see better! It most often appears around 45 years old.

• Distorted vision, duplicate letters: awọnAstigmatism

If the cornea of ​​the eye, and sometimes the lens, is distorted, then the incoming light rays will also be deflected, or even doubled. As a result, the image on the retina will be misshapen, both near and far. Those affected see twice, often blurry. Astigmatism can be due to a birth defect, with an oval shaped cornea called “rugby ball” instead of round, or as a result of a disease such as keratocone.

Treatment for ametropia depends on its origin and characteristics. We can try to modify the rays entering the eye, using glasses and lenses, or to operate to change its internal structure.

Aini idena

The various cases of ametropia are linked to the development of the body, so there is no preventive means to prevent, for example, myopia. The ideal remains, for young children, to quickly detect the first signs of ametropia in order to find a solution.

Gilaasi ati awọn lẹnsi

The most common solution in the treatment of ametropia is to wear glasses or contact lenses, to be placed directly on the cornea. Thus, for myopia, hyperopia, or presbyopia, wearing corrective lenses makes it possible to modify the angle of the light rays at the input. This is to compensate for deficiencies in the cornea or lens, and to ensure that the rays focus as intended on the retina, rather than in front of or behind it.

Ilana itọju

There are also different surgical treatments, the goal of which is damage to the eye. The idea is to change the curvature of the cornea, most often by removing a layer on it with a laser.

The three main surgical operations are as follows

• lasik, the most used

The LASIK operation (for ” Laser-Assisted in-situ multiplication ») consists of cutting the cornea using a laser to remove a little thickness. This changes the curvature of the cornea and compensates for errors in the lens.

• PRK, more technical

The PRK operation, photorefractive keratectomy, uses the same method as LASIK but by removing small fragments on the surface of the cornea.

• Intro-ocular lenses

Advances in eye surgery make it possible to implant “permanent” lenses directly under the cornea (which can be removed during new operations).