Posterior vitreous detachment caused by various reasons such as age, eye trauma, high myopia, etc., resulting in dark shadows in front of the eyes is mostly due to Weiss ring, which usually cannot disappear and does not require special treatment. Posterior vitreous detachment is the separation of the posterior vitreous cortex from the inner surface of the retina, which can appear in front of the patient’s retina as an optic disc-sized ring-like turbidity, also known as Weiss ring, manifested as a black shadow in front of the patient’s eyes, which is usually difficult to disappear. However, it does not usually impair the patient’s visual function and usually does not require special treatment. It is recommended to avoid strenuous exercise and visual fatigue. When retinal detachment occurs and the macular area of the retina is damaged, the patient may have a fixed and large black shadow, which can seriously impair the patient’s vision. It is recommended that patients with obvious dark shadows and other discomforts should consult a doctor for evaluation of their condition and follow the doctor’s instructions for treatment.