What Is High Myopia?

Basic Information

Causes of high myopia

1. Genetic factors Myopia has been recognized to have a certain genetic predisposition, especially for high myopia. Those with genetic factors have an earlier age of illness, and their degrees are above 600 degrees. But there are also people with high myopia and no family history. High myopia is autosomal recessive.
2. Developmental factors Because the eyeballs are smaller in infancy, they are all hyperopia, but as the age increases, the axis of the eye gradually grows, and the development is normal until the age of 6 years. If over-development occurs, myopia is formed. This type of myopia is called simple myopia, which usually starts at school age, and is generally lower than 600 degrees. Development stopped around the age of 20. Such as the rapid progress in childhood, 15 to 20 years of age progress more quickly, and then slow down, this type of myopia is often higher than 600 degrees, can reach 2000 to 2500 or 3000 degrees. This myopia is called high myopia or progressive myopia or pathological myopia. This type of myopia can lead to degenerative retinal choroidal lesions in old age, so vision can gradually decrease, and optician cannot correct vision.
3. Environmental factors People engaged in text work or other close work have more nearsightedness, and there are more nearsightedness among young students, and the prevalence of it has increased significantly since the fifth and sixth grades. This phenomenon shows that the occurrence and development of myopia are closely related to close work. Especially the eyeballs of adolescents are in the stage of growth and development, with strong adjustment ability, and the extensibility of the ball wall is relatively large. The adjustment and collective action during close work such as reading makes the medial rectus muscle exert a certain pressure on the eyeballs. Internal pressure may also rise.

Clinical manifestations of high myopia

1. Far vision is reduced and near vision is normal. The collection is weakened, and may have exotropia or occult obliqueness, and often have visual fatigue.
2. High myopia, mostly belongs to axial myopia, the anterior and posterior axis of the eyeball is elongated, and its extension is almost limited to the posterior pole. Therefore, it often shows that the eyeballs are more prominent, the anterior chamber is deeper, the pupils are large, and the reflection is slower. . At very high levels of myopia, the lens cannot support the iris at all, resulting in mild iris tremor.
3. Dark adaptation is reduced.
4. High myopia, due to excessive elongation of the axis of the eye, can cause degenerative changes in the fundus: Leopard-shaped fundus; Choroid atrophy around the optic disc; Irregular, separate or fused white can occur in the macula Atrophic spots, sometimes visible bleeding. In addition, small round hemorrhages were occasionally seen near the macula, called Foster-Fuchs plaques; posterior scleral edema; cystoid degeneration of the serrated margin.

High myopia

Eye examination includes naked eye vision, corrected vision, intraocular pressure measurement, fundus examination, etc., and computer optometry and dilated pupil examination. Corneal maps, corneal thickness gauges, and slit lamps are also used to check the cornea, refractive interstitial, fundus, corneal thickness, and radius of curvature.

High Myopia Diagnosis

According to far and near vision, diopter, and fundus, combined with mydriasis and optometry, a clear diagnosis can be made.

High Myopia Complications

Common complications include vitreous degeneration, cataracts, macular holes, and glaucoma.

High Myopia Treatment

1. General treatment promotes eugenics, avoids genetic factors; cultivates correct reading habits, and pays attention to nutritional balance.
2. Wear glasses to place an appropriate concave lens in front of the near-sighted eye, and the parallel rays of light will be dispersed into the eye after passing through it, so the focus will move backward and fall directly on the retina to obtain clear far vision. The principle of selecting the power of the concave lens for correcting myopia is to select the lens with the smallest power as the eye lens from several concave lens lenses to obtain normal vision (1.0 to 1.2) or the most satisfactory vision (that is, the best vision when the correction is less than 1.0). Correction degree.
3. Surgical treatment (1) Corneal surgery: including excimer laser in situ keratomileusis (LASIK), excimer laser keratotomy (PRK), and less commonly used autolaminoplasty, corneal ring placement, Surface corneal transplantation, corneal lens surgery, etc. This type of surgery is generally used for those who have stopped developing myopia. Surgery can correct myopic refractive error by changing the curvature of the cornea, but it has no effect on the fundus changes and various complications of pathological myopia.
(2) Lens surgery: Clear lens extraction has been performed for highly myopic eyes to correct refractive errors for a long time, but it is necessary to pay attention to complications such as retinal detachment and macular edema after surgery. In recent years, phacoemulsification combined with intraocular lens implantation has been effective. Some people who have high myopia for the transparent lens have placed an artificial lens in front of the lens to correct the refractive error, and have achieved a certain correction effect. This method has a strong ability to correct refractive errors. For high myopia above 1200 degrees, the cornea is thinner. It is estimated that it may be more suitable for those who have difficulty in correcting corneal refractive surgery.