Automatic flip mirror–Principle 1, slow down eye fatigue principle: adjustment lag (i.e. adjustment is not sensitive) is the key link in the occurrence and development of myopia in students. This mirror can make the focus of attention from the front of the eye fogging (virtual) jump to 5 meters away, and then jump back to the front of the eye, thus significantly improving the sensitivity of eye adjustment, relieve eye fatigue. When the front lens is turned upward, there is a transient visual haze, turned down immediately clear, this haze clear flip process, is the process of eye regulation muscle exercise, flip lens can significantly relieve vision loss due to eye fatigue. 2, to relieve presbyopia: the cause of presbyopia is that as we grow older, the crystalline lens is gradually hardening and ciliary muscle strength becomes weaker, resulting in a decline in the ability to regulate the close to the occurrence of difficulties. By training the adjustment sensitivity, the symptoms of presbyopia can be relieved.