Myopia causes a difficulty in vision, the defect is measured in diopters, the stronger myopia higher the number of missing diopters (-1, -2, -3, …… ..). With the growth of the visual defect, it decreases the distance over which you can focus on objects (to -4 is only 25 cm).
The main cause of myopia is the length of the eyeball in the eye nearsighted and higher than normal in the eye which is called in the jargon eye emmetropic.
More rarely myopia can be determined from the greater curvature of the cornea or the lens.
Because of the greater length of the eyeball images ranging in focus not on the retina but in front of it.
Foto concessione: Dott. C. Benvenuti
Myopia is defined as:
- Mild up to four diopters
- Average up to eight diopters
- High over the eight diopters
There is also distinction between physiological myopia and pathological myopia (degenerative).
The myopic eye is not a diseased eye, but the medium and the high myopia may also predispose to major retinal disorders, so you need to undergo periodic checks of the retina fund by contacting your ophthalmologist.
The myopia is corrected with diverging lenses (concave) that move the point at which converge the light rays so much the more the greater the correction, to compensate for the greater length of the bulb.
In the case of myopia, as in all the defects of refraction, it is possible to intervene with surgery to reduce the problem is partially or even totally. It must be emphasized, however, that when you undergo this type of surgery the eye remains structurally short-sighted and is therefore also have to undergo periodic checks by an ophthalmologist.