The word amblyopia is of Greek origin and literally means “retardation of vision”. Amblyopia is defined as a loss of vision in one eye due to abnormal binocular interactions, or a loss of vision in one or both eyes due to actinic deprivation during the developmental phase of vision, and no treatment is found during the eye examination to reverse the vision. Amblyopia is a functional loss of vision in one eye due to “disuse” or “misuse” of the eye during a critical period of visual development. No organic abnormalities are found during the ocular examination. Although the mechanism of vision loss is not exact, it is generally believed that the cause is in the visual cortex (the center of the brain that governs vision). Amblyopia leads to reduced visual acuity, binocular vision, depth perception, and contrast sensitivity. The formation of fusion and stereopsis in the center depends on the simultaneous stimulation of both eyes to form a clear image (seeing things in three dimensions, this function is not good enough to affect the choice of some special professions, such as microsurgeons, pilots, painters, not being able to drive fast on the highway, not being able to enter the garage easily when reversing).