Lens protrusion

Introduction Lens protrusion is one of the symptoms of myopia. It is a common problem among all myopic patients. Some people do not see the eyes prominent but actually protrude inward. Because the growth of the eye axis is the main cause of myopia. Once the eye has developed myopia, that is, the eye axis has become longer, and the eyeball will appear slightly protruding due to the length of the front and rear axles.

Cause

The causes of myopia are due to internal and external causes:

1. Internal cause

(1) Genetic quality: Myopia has a certain genetic tendency, which has been recognized, especially for high myopia. But for general myopia, this tendency is not very obvious. Those with genetic factors, the age of the disease is earlier, more than 6.00D. But there are also people with high myopia, no family history. High myopia is autosomal recessive, and general myopia is a multifactorial genetic disease.

(2) Developmental factors: Infants are hyperopia because of their small eyeballs, but as the age increases, the axis of the eye gradually lengthens and develops normally until puberty. If over-development occurs, myopia is formed. This type of myopia is called simple myopia, and it starts at school age. Generally less than 6.00D. It will stop growing until about 20 years old. If you progress very quickly in your childhood, you will progress faster when you are 15 to 20 years old, and then slow down later. This type of myopia is often higher than 6.00D, which can reach 20D ~ 25D or 30D. This type of myopia is called high myopia or progressive myopia or pathological myopia. This kind of myopia can be delayed and degraded in later years, so the vision can be gradually reduced, and the glasses cannot correct the vision. Myopia is rarely found at birth, but very few are congenital.

2, external factors: that is, environmental factors, engaged in text work or other close-time work, more myopia, adolescent students also have more myopia, and from the fifth and sixth grades of primary school, its prevalence has increased significantly. This phenomenon indicates that the occurrence and development of myopia is closely related to close work. Especially the eyeballs of adolescents are in the stage of growth and development, the adjustment ability is very strong, the stretch of the ball wall is also relatively large, and the adjustment and assembly of the reading, sending and receiving rooms, etc. during close working, make the external muscles (mainly inner straight) The muscle exerts a certain pressure on the eyeball, and the intraocular pressure also increases accordingly. As the operation increases, the frequency and time of adjustment and collection gradually increase. The ciliary muscle and the extraocular muscle are often in a state of high tension. Excessive effects can cause ciliary muscle spasm, causing temporary vision loss. However, after rest or use of the ciliary muscle emollient, vision may improve in complete recovery. Therefore, some people call this kind of nearsightedness as functional myopia or pseudomyopia. However, under the long-term mechanical compression of the scleral tissue, the wall of the ball gradually extends, the axis of the eye is elongated, and the degree of myopia is deeper and deeper, and can no longer be alleviated by atropine. Especially in adolescence, not paying attention to visual hygiene is the direct cause of myopia. Not paying attention to general health can promote the development of myopia.

Recently, some people have used the forward-looking research method to observe the role of environmental and genetic factors in the pathogenesis of myopia. The method is for students with normal vision, who are affected by myopia after two years of follow-up. Factors are analyzed and judged. The results are as follows: in terms of genetic factors: the ratio of the new prevalence of myopia is 1:2.6:3.8 for children with no nearsightedness, one with myopia, and both for myopia; in terms of environmental factors: the reading time after class is 1 The ratio of the new prevalence of myopia of ~2h:3h:4~5h was 1:2.1:3.2. Therefore, genetics and the environment are two important factors that affect students' myopia.

In addition, in a broad sense, the pollution of trace elements in the atmosphere, the change of nutrients and the teaching aids that do not meet the requirements of ergonomics are also objective factors, and there are reports that affect the occurrence of myopia in students. However, these factors are secondary to the comparison of nearsightedness.

an examination

Related inspection

Lens examination ophthalmoscopy

1. Vision: The most prominent symptom of myopia is reduced distance vision, but near vision can be normal. Although the higher the degree of myopia, the worse the vision, but there is no strict ratio. Generally speaking, for myopia above 3.00D, the distance vision will not exceed 0.1; the 2.00D is between 0.2 and 0.3; the 1.00D is up to 0.5, and sometimes it may be better, see (Figure 1).

2, visual fatigue: especially in low-level people, but not as obvious as hyperopia. It is caused by the inconsistency between adjustment and collection. High myopia Because the gaze target is too close to the eye, the collective effect can not be matched with it. Therefore, monocular gaze is often used, but it does not cause visual fatigue. 3. Because the eye position does not need to be adjusted when the eyesight is near, the function of the collection is relatively weakened. When the balance of muscle strength cannot be maintained, the visual function of both eyes is destroyed, and only one eye is viewed, and the other eye is biased to the outside. Temporary alternating strabismus. If the visual function of the oblique eye is extremely poor and the deflection occurs earlier, the oblique eye loses the fixation ability and becomes monocular external strabismus.

4, eyeball: High myopia, mostly belongs to axial myopia, the front and rear axis of the eye is elongated, and its elongation is almost limited to the posterior pole. Therefore, the eyeball is more prominent, the anterior chamber is deeper, the pupil is large and the reflection is slower. Since there is no conditioned stimulus, the ciliary muscle, especially the annular portion, becomes atrophic, and in extremely high myopia, the crystal can not support the iris at all, and mild iris tremor occurs.

5, fundus: low myopia eye changes are not obvious, high myopia, due to excessive elongation of the eye axis, can cause degenerative changes in the fundus.

(1) Leopard-like fundus: the blood vessels of the retina become thin and straight after leaving the optic disc. At the same time, due to the elongation of the choroidal capillaries, the nutrition of the retinal pigment epithelial layer can be affected, so that the superficial pigment disappears and the choroidal blood vessels are exposed, forming a leopard. Streaked fundus.

(2) The choroid around the optic disc of the myopic arc is pulled away from the temporal side of the nipple under the traction of the scleral stretch, and the sclera behind it is exposed to form a white curved spot. If the posterior pole of the eyeball continues to expand and extend, the choroidal dislocation gradually extends from the temporal side of the nipple to the periphery of the optic disc, finally forming an annular plaque. Irregular pigments and hardened choroidal blood vessels can be seen in this plaque.

(3) Irregular, separate or fused white atrophy can occur in the macula, and bleeding can sometimes be seen. In addition, occasionally there is a degenerative lesion near the macula, which is a black ring-shaped area, which is slightly smaller than the optic disc, with a clear boundary, and a small round hemorrhage can be seen at the edge, called Foster-Fuchs plaque.

(4) Post-scleral glomal: The extension of the posterior part of the eyeball, if limited to a small part, can be seen from the section of a sharp protrusion, called the posterior scleral staphyloma. This atrophic lesion, such as occurs at the macula, can incorporate central vision operations.

(5) Cystic degeneration of the serrated margin.

Differential diagnosis

Differential diagnosis of lens protrusion:

1. Eyeball protrusion: Eyeball protrusion refers to the eyeball protrusion exceeding the normal range. The normal eyeball protrusion of Chinese people is 12-14m, with an average of 13mm, and the difference between the two eyes is no more than 2mm. Eyeballs can be signs of eye disease or symptoms of systemic diseases. In addition to the disease itself in the sputum, it is often closely related to diseases of internal medicine, otolaryngology, neurosurgery, and oncology.

2, limited scleral swelling: limited scleral swelling: when the posterior part of the degenerative myopia significantly increased, the posterior pole can produce limited scleral swelling, the edge can be slope-shaped, can also be Steep.

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