Pathological myopia

Introduction Pathological myopia occurs earlier (can occur between 5 and 10 years old), and progresses rapidly. After 25 years of age, the development of myopia can reach -15.00D or more, often accompanied by fundus changes, and vision is not easy to correct. Called degenerative myopia. It is an eye disease characterized by progressive deepening of diopter, increasing axial length, visual impairment of eye and retinal choroidal tissue. It is one of the common eye diseases in China, and its prevalence is about 1%~2%. . Typical pathological myopia has the following characteristics: 1, is a rare type of myopia, accounting for about 2%. 2, usually occurs before the age of 12, the eyeball is obviously elongated, and the annual increase of -4.00 diopter. Can be developed to -10 ~ -20 diopter. It is usually stable until the age of 20, but it may also develop after the age of 30. 3, the size of the eyeball increases with age, so that the degree of myopia continues to deepen, vision is seriously reduced. In many cases, neovascularization (neovascularization) occurs under the macula. 4, highly pathological myopia (more than -7 diopters) prone to retinal choroidal degeneration, vitreous floatation and liquefaction, retinal tears, resulting in retinal detachment. 5, prone to open angle glaucoma.

Cause

Pathological myopia has obvious genetic factors, and biomechanical factors are another important factor in the etiology of high myopia. Long-term reading and subtle eyesight work are one of the important causes of simple myopia, and can also deepen the refractive power of pathological myopia.

The relationship between pathological myopia and diopter, common model eyes is satisfied: V=U+P1, where V=object image refraction distance, U=object refraction distance. P1 = refraction caused by the total diopter of the eye. P1=60 on the model eye. The far point of -10.00D myopia is 10 cm (U = -10 cm) in front of the cornea, and V = 60-10 = 50 cm.

The law of pathological myopia inheritance is: if one of the pair of genes is normal, and the other is abnormal, it is not a disease, it is called a carrier; if two degenerative myopias are married, most or all of their children are infected; If a transsexual myopia is married to a normal person, the child is a carrier; if the transsexual myopia is married to the carrier, half of the children have an onset. Therefore, to prevent degenerative myopia and improve the quality of the population, it is necessary to start from the genetic eugenics consultation work, it is possible to prevent problems before they happen.

an examination

Related inspection

Ophthalmology examination, dilated optometry, near vision test, logarithmic vision, band photodetection

According to the condition and the surgical method, you need to choose the following items: vision, optometry, adjustment function, main eye, IOLmaster, corneal endothelial cell count, retinal vision, fundus color photography, Opel, fundus angiography, OCT, visual field, B-mode , ocular electrophysiology, contrast sensitivity, corneal thickness, corneal diameter, corneal topography, etc.

Differential diagnosis

Differential diagnosis of pathological myopia:

1. Myopic astigmatism: Myopic astigmatism, also known as simple myopic astigmatism, refers to parallel rays entering the eye. Parallel rays on a main meridian are imaged on the retina, and parallel rays on the other meridian perpendicular to it are imaged in front of the retina. It is myopic astigmatism. Focusing on the retina, parallel rays are reflected. In front of the retina, the focus is reflected, and the reflected light is collected. Therefore, it should be corrected by a concave cylindrical mirror.

2. Myopia arc: Since the posterior part of the wall of the high myopia is protruding backward, the optic nerve enters the ball obliquely. The side of the optic papilla (mostly the temporal side) is displaced backwards, so that the optic papilla loses its normal vertical elliptical shape under the ophthalmoscope and becomes significantly vertical (or lateral, oblique (oval, even like a braid) There is a crescent spot called the conus, or the extensive conus. It is the most common fundus change in myopia. The smallest is not easy to see. Out, the large can reach the size of the optic disc. Some surround the optic disc, and even reach the macular area. If the near vision arc does not invade the macular area, it has little effect on vision; for those who invade the macula, the visual acuity (including near vision) drops significantly. It is difficult to determine whether myopia is still in progress according to the shape of the arc alone. However, according to fundus observation, if the edge is clear, it can be speculated that myopia has stopped; otherwise, if the edge is irregular, the expansion of the eyeball may still be In progress. When the range of myopic arc is large, especially when scleral cone or scleral staphyloma has formed, the optic disc is not perfectly round due to the inclination of the optic canal, but becomes a longitudinal ellipse. The cornea from the temporal side portion farther than nasal, is a cause of inclination of the disc surface occurs.

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