Classification of myopia
There are many classification methods from different perspectives.
1. According to clinical pathology, it can be divided into simple myopia and progressive myopia.
Simple myopia: that is, general myopia, with a diopter usually below 600 degrees, medium to low myopia, and myopia develops slowly. The eyeball tissue is normal and no pathological changes occur.
Progressive myopia: The so-called high myopia, also known as pathological myopia, has a diopter of more than 600 degrees and can reach up to 4000 degrees. Generally, the onset of disease is early, the axial diameter of the eyeball continues to lengthen, and many tissues of the eyeball may undergo a series of pathological changes.
2. According to the degree of myopia, it can be divided into low, moderate and high myopia.
Low myopia: diopter less than or equal to 300 degrees.
Moderate myopia: myopia with a diopter between 300 and 600 degrees.
High myopia: those with a diopter higher than 600 degrees.
3. According to the influence of eye accommodation, it can be divided into pseudomyopia, true myopia and mixed myopia.
This type of myopia generally falls into the category of simple myopia.
Pseudomyopia: Also known as accommodative myopia, the axial length of the eyeball is normal, but the refractive power of the refractive interstitium exceeds the normal value. This is generally due to overaccommodation of the lens, so distant light rays enter the eye and are imaged. in front of the retina. After mydriasis, the refractive power of myopia completely disappears, manifesting as emmetropia or hyperopia.
True myopia: Also called axial myopia, the refractive power of the refractive stroma is normal, the anteroposterior diameter of the eye axis is extended, and distant light enters the eye and is imaged in front of the retina.
Mixed myopia: a state in which true and false myopia coexist. After mydriasis, myopia diopter is reduced more, but myopia is still myopia. Young myopic students often suffer from this state of myopia during their heavy learning tasks and physical development.