The main symptom is a flashing sensation or a dark shadow in front of the eye that rotates and flutters with the eye. However, vitreous liquefaction does not have a significant effect on vision and is related to age. The other condition is due to retinal detachment, which can also appear as a flashing sensation in front of the eyes, but will be accompanied by a significant loss of visual acuity, and requires fundus photography to make a clear diagnosis. If the detachment is caused by myopia, it is also necessary to avoid eye fatigue and prevent the continuous growth of myopia.