Generally speaking, vision refers to the minimum separable vision of the eyes, not the minimum visible vision, so the eye chart reflects the minimum visual angle separated by the two points of the subject's gaze, that is, the minimum separable vision or 1 visual angle vision, which can represent the subject's best visual function.
When the child is 1 month old, his vision is light; When it is 3 months old, it is 0.02, which means that it can track moving objects in front; 1 0.2 at age; 0.4 at the age of 2; At the age of 3, it is 0.6, that is, you can read the eye chart and check your vision with the eye chart; 0.8 at the age of 4; At the age of 5, you can reach 1.0, which is adult vision. If not, you should go to the hospital as soon as possible. At the age of 6, the visual acuity can reach 1.2.
Extended data:
If the examinee can't recognize any characters on the eye chart at a distance of 5 meters, he can stay close to the eye chart until he can recognize the "0. 1" line mark on the eye chart. At this time, the calculation method is: visual acuity =0. 1× the distance of the subject (m) /5 (m). If the opening direction of 0. 1 can be recognized at 4m, record "0.08" (0.1× 4/5 = 0.08); Similarly, if the opening direction of 0. 1 is determined at 2 meters, it is "0.04" (0.1× 2/5 = 0.04).
If the examinee can't see the line mark of "0. 1" clearly at1m, let him count the doctor's fingers and record the farthest distance that can be cleared. For example, if he can see the index clearly at 30cm, it is recorded as "30cm index" or "CF/30cm". If the doctor can't identify the index by moving his finger to the nearest distance, he can identify whether there is hand tremor in front of his eyes and manually record the farthest distance he can see, for example, at 10cm, and record it as "manual 10cm" or "HM/ 10cm".
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