Visual pathologies (1)

Short description:

Myopia is the result of errors of refraction causing a poor distant vision without affecting near vision. It is measured in negative diopters.
Symptoms vary according to myopia's severity and its onset age; and whether it affects one eye or both eyes.
Myopia is detected at an ophthalmological check-up carried out by the ophthalmologist
Treating myopia consists in correcting it through 3 main approaches: spectacles, lens and surgery.
Myopia complications may occur; they will remain whatever the means used to correct it.

Type of publication:

Good practises

Date of publication:

10/25/2012

Author(s):

Sylvie ERVE

Publishing organization:

centich

Categories:

Long description:

Myopia: what is it?

 Myopia is the result of errors of refraction causing a poor distant vision without affecting near vision.
What are myopia’s symptoms?
Symptoms vary according to myopia's severity and its onset age; and whether it affects one eye or both eyes:

 - decreased far/distant vision which may result in having to squint when looking into the distance, not recognizing « friends » when passing by them in the street, child having to look closely at the school chalkboard or the TV set, or who always writes very close to his school book;
- visual fatigue and/or headaches, particularly when eye-gazing;
- discomfort when driving, especially in the evening or at night.
A slight myopia in adults may go unnoticed; as well as a more important one in children.
What are myopia’s risks factors?

The risks are mostly hereditary, that is to say genetic. As the size of the eye is genetically determined, most scientists believe that myopia is a hereditary disorder, sometimes with one skip generation.
Environmental factors such as exposure to heat and light also play their part.
Furthermore, certain pathologies seem to promote myopia:

 - Elastin fibers disorders,
- Inflammatory disorders (scleritis),
- Damages due to traumas.

 How to diagnose?
Myopia is detected at an ophthalmological check-up carried out by the ophthalmologist. First signs might be symptoms here above mentioned or first possible detection may be made during a visit to the GP, or to an occupational doctor, or to maternal and child protection centers, or to a pediatrician, orthoptists or opticians.
During such a check-up, painless though sometimes impressive examinations (cornea curves measurement, visual acuity assessment...) will be carried out.
It might sometimes be necessary to use an ophthalmic solution in order to widen the pupils and to disregard false myopias.
Finally, an oculomotorius or an eye fundus check-up may be required.

 How to treat myopia?
Treating myopia consists in correcting it through 3 main approaches:

• wearing concave glasses, also called diverging or with a negative power. The glasses center is thinner than the periphery. When treating heavy myopias, the optician will propose, for aesthetic reasons, a spectacle frame with small glasses providing a higher rating/index and/or of a specific shape so as to lower the glasses thickness/weight.

• Wearing contact lenses: flexible or hard. This needs testing in order to obtain a good visual acuity and ensure that the cornea can tolerate the lenses. They enable an enhanced field of view and gaze. Glasses may still be necessary in case there is the need for a temporary lenses adaptation period.

• Surgery and laser: there are 3 possible ways:
o Keratotomies are the oldest technique, which consists in an incision of the cornea in order to reduce its curvature.
o EXCIMER laser: it reduces cornea’s surface thickness ; this can cause heavy pain during the days following the surgery.
o LASIK combining surgery and laser treatment. A small opening at the surface of the cornea is performed under surgery, making it possible to lift its surface for laser access and treatment; and then shut afterwards. There is no postoperative pain.

 This treatment does not eliminate myopia’s risks of complication.

 What are these possible complications?
Myopia complications may occur; they will remain whatever the means used to correct it.
For instance:
• Myodesopsia or « hovering flies » caused by an earlier vitreous liquefaction due to myopia: perception of moving dots/marks, particularly when looking at a light background (pages or white walls);
• Retinal detachment: perception of hovering flies, lightning or flashes of light in a specific direction followed by the appearance of a grey film on one part of the eye without pain. At this stage, this will be treated via surgery. The best treatment is preventing this by undergoing regular retinal check-ups against predisposing lesions which could then be laser treated;
• Macular degeneration: along with a decreasing or distorted vision, in the form of edemas, bleeding, retinal detachment or macular holes;
• Early cataract: happening on average 10 years earlier in patients with myopia ;
• Glaucoma are more frequent in patients with myopia.

 How many people are affected by myopia?
In Europe, 20% of the population aged less than 20 is affected by myopia;
In France, at least 25% of the population aged less than 20 is affected by myopia.

Copyright information:

import from Sensage project