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When measuring vision with an eye chart, the examinee should be 5 meters away from the eye chart (if not satisfied, mirror reflection can be used), and above 1.0 is normal vision. Generally, it is determined from the lower level to the higher level of the eye chart until it is unrecognizable; However, in practice, because the vision level of the whole group is not bad, in order to save time, some subjects like to let the testers distinguish the most difficult ones.
Some friends have really poor eyesight. They still can't see the E-shaped gap of 0. 1 clearly within 5 meters. At this time, let him approach until he can see clearly. At this time, his vision is: vision =0. 1× distance (m) /5. If you still can't see the E-shaped gap on the eye chart within half a meter, then the tester should identify the indicators, measure the manual, light perception and so on.
Record vision according to the examination.
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Precautions:
1. Generally speaking, people with ametropia have poor eyesight. The higher the diopter, the lower the naked eye vision. But this is not absolute. Some people have low diopter, but their eyesight is very poor, because diopter is not the only factor that affects their eyesight. If the eyes have other diseases or retinal imaging function, impaired optic nerve function, etc. , but also reduce vision.
2. Constant diopter does not mean that vision cannot be changed. Timely and reasonable intervention and gradual accumulation of achievements can effectively control the growth of myopia and prevent the degree of myopia from deepening rapidly.