Myopia: definition, vision of the eye, can it disappear?

Myopia is a vision disorder that tends to increase in the world. She is especially present in Asian countriesto reach Singapore and Taiwan more than 80% in some populations of young school children, reported the French Society of Ophthalmology in 2019.

What is the definition of myopia?

The term “myopia” comes from the Greek “muopia” which means “I close one eye” in reference to the attitude of nearsighted people who, to see better from afar, tend to partially close their eyes. Myopia is therefore a vision disorder and more precisely described as a refractive errorthat is to say the convergence of light rays through the various structures of the eye. Myopia generally appears in childhood, between 8 and 12 years old, and progresses slowly with age to stabilize around 20-25 years old. A late onset of myopia should suggest a beginning cataract. The most frequent myopias (eye too long) are axile myopias.

We distinguish three levels of myopia :

• there mild myopia is between – 0.25 and – 2.50 diopters,
• there medium myopia is between – 2.75 to – 6 diopters,
• there high myopia is between – 6 diopters and beyond. In this case, the eye is longer and can lead to complications (early incidence of cataracts, increased risk of glaucoma). This pathological myopia exposes to a decrease in visual acuity over time, despite optical correction.

Can myopia disappear?

Apart from myopia or cataract surgery, very slight myopia can disappear with age.

Myopic people see blurred from afar and perfectly clear up close. “But he is very difficult to integrate that we see badly from afar because the brain works and tries to make things visible. If myopia is not detected, there is often no symptoms in child who does not realize that his sight is degraded, its accommodative power is enormous.”

What is progressive myopia?

“During progressive myopia, the child sees his myopia increase very rapidly and lose several diopters in the space of a few months: the axial length of the eye increases very quickly, the eye lengthens like a rugby ball” explains Dr. Xavier Subirana, ophthalmologist. “It’s a real race against time” he continues. The objective is to carry out a very regular follow-up in order to slow down the progression of myopia and prevent it from exceeding 6 diopters. Having at least one myopic parent, if not both, increases the risk of progressive myopia.

A child whose parents are myopic is more likely to be affected by myopia in turn.

What are the causes of myopia?

Myopia is usually due to an eye that is too long, or a cornea that is too curved. With a normal eye, the perceived image is formed on the retina. On the other hand, in the case of a myopic eye, objects are projected in front of the retina. Too powerful a lens, a keratoconus or some cataracts can make myopic. In the case of very strong myopia, degenerative lesions of the fundus (choroid, sclera and retina) are added to the abnormality of the eye. This visual disturbance is caused by factors genetic And environmental. A child whose parents are myopic is more likely to be affected by myopia in turn. Myopia would also be favored by the lack of exposure to sunlight and by the intensive practice of indoor activities or by a position too close to the computer screen.

What are the symptoms of myopia?

Myopic people see blurry from afar and clear up close. Among the call signs : the child tires quicklyit may have headachea poor distance vision on the board or close reading of books and notebooks. Medium and high myopia (above 6 diopters) can cause complications : retinal tear And peeling off retina, choroidal atrophy or myopic choroidosis, glaucoma, cataract…

Myopia is usually detected in childhood or adolescence. Rare are the people in whom the first signs of myopia appear in adulthood. Regular check-ups with an ophthalmologist can diagnose myopia and to assess the level of seriousness at an early stage. “As children have a strong accommodative power, ophthalmologists often ask to see them again on a cycloplegica product that temporarily blocks accommodation and provides adequate correction of myopia” explains Dr. Subirana. They also measure the axial length, ie the length between the cornea and the retina in order to be able to monitor myopia. THE follow-up of the myopic child must therefore be very regular. The young adult will consult every 2 years and every year thereafter, especially if he suffers from severe myopia in order to prevent possible complications.

What are the treatments for myopia?

It is possible to curb progressive myopia with:

• I’orthokeratologythat is to say rigid lenses to wear at night. “They are to be worn every night and people have to sleep on their back and not move during the night so that the lens stays in place” says Dr. Subirana
• Of the eyeglasses bifocals with prisms that give moderate results.
• Soft lenses that work on the basis of image defocus.

“We decide on a case-by-case basis depending on the character of the child and his ability to comply with the treatment” says the doctor. Research is underway on treatments based on atropine which would make it possible to curb myopia. It is also important to keep a certain distance from screens and practice outdoor activities on a daily basis. “The correction is only done when the myopia is stabilized” reports the specialist. Glasses and lenses adapted to the person’s sight are thus used.

What is the myopia operation?

The objective of the myopia operation which appeared in the 1980s is to correct refractive defects of the eye by adequately sculpting the cornea and allow to recover an almost normal view and do without correction. It is either corneal surgeries during which the cornea is “sculpted” laseror intraocular surgeries, with placement of a implant in front of the lens or replacement of this natural lens of the eye which loses its transparency over time. Before the operation, the patient must make a preoperative assessment and one medical interview to ensure that he is eligible for these techniques and that he is not at risk of an adverse effect. The intervention is usually done under local anesthesia : the eye is numbed only by the instillation of drops or possibly by injections around the eye. General anesthesia is also possible. The patient comes out the same day with the surgeon’s instructions. Myopia surgery is considered a comfort operationit is therefore not not reimbursed by social security. However, some mutuals cover part of the costs. These vary from 3,000 to 3,500 euros for both eyes, clinic fees included.

Laser and myopia

Several types of lasers can be used in refractive surgery. Lasers are medical devices. They therefore have a CE marking obtained following certification issued by an organization called a “notified body”. Among the surgical techniques practiced, the technique LASIK represents more than 85% of procedures practiced in France.

It is performed in three surgical stages:

• The preparatory cut of the flap which, when lifted, exposes the surface of the cornea to be treated. This cutting is done by a mechanical blade, also called microkeratome (now less used) or by a femtosecond laser.
• The sculpture of the corneal tissue with the “excimer laser”; the shape of the sculpture is adapted to the defect to be corrected.
• Replacement of the corneal flap on the eye, without suturing.

Although deemed effective and widely used, this technique has limitations:

The results of this surgery are not always definitive.

The need to still have to wear glasses or contact lenses cannot be completely excluded.

Indeed, the correction of the patient evolves naturally according to his age and he may have to wear glasses later, especially in the case of presbyopia. The need to still have to wear glasses or contact lenses cannot be completely excluded. The result is sometimes imperfect and it is then necessary to carry out a second operation called “retouch“. There dry eye is the main adverse effect of refractive surgery. More rarely, infections and complications affecting the corneal flap may occur.

Thanks to Dr. Xavier Subirana, ophthalmologist.