Because the appearance of both eyes is not abnormal, and a significant number of children have normal or near-normal vision in one eye, it is difficult to detect, so parents should regularly seek professional ophthalmologist examination. Careful parents can observe whether their children have the following performance: 1, children read books, television when closer and closer; 2, often squint to see things, or tilt their heads with a glance; 3, children’s reaction to the surrounding environment than children of the same age, or in an unfamiliar environment action is not as comfortable as familiar environment; 4, things dropped on the ground, stretch out both hands to feel for; 5, cover the left and right eyes separately, the degree of aversion is not the same. When the child is about 3 years old, parents can teach the child to identify the standard vision chart and check the left and right eyes respectively. If the vision cannot reach 0.8 or above, the child can be brought to the hospital for further examination.