The mainland is an area with a high incidence of myopia, and the prevalence of myopia in adolescents is increasing year by year, and there is a trend of developing towards a lower age and a higher number. In addition, the pressure of going to school and environmental factors related to the modernization of life, such as the popularity of mobile phones and computers, will also have a continuous impact on the prevalence of myopia. The vision loss of primary and secondary school students is an important problem affecting the health of adolescents at present, and it is related to the improvement of the health quality of the entire nation. How to effectively prevent and treat myopia and protect the eyesight of teenagers is not only a medical issue, but also a social issue that everyone is concerned about, but at present, there are still many people who know less about the prevention and treatment of myopia.
Normally, when the eye is relaxed, parallel light rays pass through the refractive system of the eye and focus on the retina. In myopic patients, parallel rays of light pass through the refractive system of the eye and are focused in front of the retina. The occurrence of myopia is affected by a combination of genetic and environmental factors.
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Q: How many classifications are there for myopia?
Answer: 1. According to the refractive component, it is divided into: refractive myopia and axial myopia.
Refractive myopia: Mainly due to excessive curvature of the cornea and lens, the refractive power is beyond the normal range, while the axial length is within the normal range.
Axial myopia: the axial length is outside the normal range, and the curvature of the cornea and lens is within the normal range. Most of the myopia in children and adolescents is axial myopia. Axial myopia is caused by a long anterior and posterior diameter of the eye (axial eye). The eye axis of a normal adult is about 24mm, and for every 1 mm extension, the myopia degree will increase by about 200~300 degrees, and the specific value varies from person to person.
Therefore, the longer the eye axis, the higher the degree of axial myopia and the more severe the myopia. When the newborn is born, the eye axis is about 17 mm, and the refractive state presents +3D (hyperopia 300 degrees) mostly in a kind of farsighted diopter, the optical focus of hyperopia is behind the retina, and with the growth of age, the development of the eye slowly carries out the process of emmetropia, this physiological hyperopia, called hyperopia reserve. In other words, if in the process, the degree of hyperopia decreases too quickly to close to 0, it will evolve into myopia.
2. According to the degree of myopia, it is divided into mild myopia, less than 300 degrees, moderate myopia at 300-600 degrees, and high myopia greater than 600 degrees.
When you have blurred vision when looking at distant objects, squinting or squinting at distant objects, you need to do some tests to confirm whether you are nearsighted.
Q: How many ways are there to check for myopia?
Answer:
Visual acuity test: The goal is to see how blurred the vision is.
Slit-lamp examination: The purpose is to see whether there are lesions in the anterior chamber structures such as the conjunctiva, cornea, pupil, and lens, and whether the anterior chamber depth and lens are dislocated, and whether the conditions for dilated refraction are met.
Fundus examination: The purpose is to check for retinal and macular degeneration.
Optometry: The purpose of the refraction is to check the diopters of both eyes and to find corrective lenses that are both clear and comfortable for the eyes.
Ultrasound examination: The purpose of ultrasound examination is to measure the length of the eye axis and evaluate the rate of myopia progression.
Author: Tian Qi
Source: Shenyang Ninth People's Hospital
Editor: Pei Li
Proofreading: Che Jiyue, Wang Suli
First Instance: Jiang Lizhu
Review: Xu Jiang