Posterior vitreous detachment in both eyes means that the vitreous body appears to separate from the retina at several interfaces connected to the retina. It is usually mainly due to the liquefaction of the vitreous and the coalescence of the inner collagen fibers of the vitreous, which causes a cleft between the posterior vitreous interface and the retinal interface, and it results in posterior vitreous detachment, which is further divided into complete posterior detachment and incomplete posterior detachment. Complete posterior detachment usually has no effect on the retina; incomplete posterior detachment is in the part closely connected to the retina, which pulls the retina with eye movement and is more likely to cause retinal fissures and retinal detachment. Therefore, the main symptom of posterior vitreous detachment in both eyes is that there is a black shadow floating in front of the eyes, which may be a mass floating on the optic disc during ophthalmological examination.