Whether or not the brightness of the cell phone hurts the eyes depends on the environment, too bright or too dark is not good, to ensure that the light is appropriate, and at the same time to avoid a long time without stopping to look at the phone. The pupil of the eye controls the entry of light, and in a dark environment, the pupil itself will dilate to ensure that enough light enters the eye, and if there is an abnormality in the structure of the eye, then if the brightness of the cell phone is too high, it will induce glaucoma, leading to vision loss. While in a brighter environment, the pupil narrows and the low brightness of the cell phone may easily cause visual fatigue. It is recommended not to look at the cell phone in an environment with too much or too little light, and also to avoid looking at the cell phone for a long time. When vision loss occurs, it is important to seek medical treatment in time to avoid affecting the patient’s vision.