This condition is related to the distance from the anus, and the possible causes include the following aspects: 1. If it is closer to the anal opening, it may be a clinical reaction due to anal fistula, the small eye is actually the external opening of the anal fistula, and when performing surgery, it is necessary to find the external opening of the anal fistula along this small eye for incision, and the patient often has abnormal local secretion of glands, accompanied by a certain amount of pain. 2.