First, the classification of myopia
There are two main factors contributing to myopia: one is that the front and rear axes of the eyeball are too long, and the other is that the refractive power of the eye is too strong. Myopia is usually classified according to different classification criteria according to the degree of myopia, classification of refractive components, classification of pathological progression and pathological changes, and classification of dynamic anisometropia.
(1) Classification according to the degree of myopia:
Mild myopia: -3.00D and less (F≤3.00D myopia)
Moderate myopia: between -3.00 and -6.00D (3.00D<F≤6.00D myopia)
High myopia: -6.00D or above (F> 6.00 myopia)
(2) Classification according to refractive components:
Axial myopia: Myopia caused by converging imaging in front of the retina after parallel rays enter the refractive system of the eye due to axial extension. Usually, for every 1 mm increase in the axis of the eye, the refractive error increases by -3.00D. Especially in high myopia, the length of the eye axis is extremely serious, and it is usually seen that the eyeball is prominent.
Curvature myopia: Myopia caused by increased refractive power due to a decrease in the radius of curvature of the cornea or lens surface. Refractive myopia: Myopia due to increased refractive power due to increased refractive index of the refractive medium.
(3) Classification according to disease progression and pathological changes:
Simple myopia: refers to myopia caused by excessive development during development. Most refractive errors are within -6.00D (commonly known as 600 degrees). Generally, there is no obvious fundus change. Correct vision can be corrected to normal with appropriate lenses.
Pathological myopia: The disease is mainly genetic factors, followed by environmental factors, is an autosomal recessive genetic disease, mostly congenital, generally in children, onset, increasing, increasing by an average of 0.50D or 1. OD per year Corrective visual acuity is often lower than normal, and the length of the eye axis is lengthened, often accompanied by fundus lesions, and complications such as retinal detachment and cataract are prone to occur.
Secondary myopia: refers to myopia caused by other eye diseases and systemic diseases, such as keratoconus, diabetes and so on.
(4) Participate in the classification according to whether there are adjustment factors:
False myopia: In the case of normal adjustment, it refers to the use of atropine after dilation and post-examination, myopia refractive error disappears, becoming a formal or mild hyperopia. In order to regulate tension, it usually occurs in children and young people.
True myopia: normal myopia, refers to the use of atropine after dilated examination, myopia refractive error is not reduced or reduced by less than 0.50D.
Mixed myopia: refers to the examination of atropine after dilation, myopia diopter is significantly reduced, but did not return to face up. This type of myopia has both regulatory and organic factors.