Corneal fistulas are connected to the outside world and are at risk of intraocular infection and endophthalmitis, which can have serious effects on vision. In the past, cautery, fresh egg coat covering, or conjunctival flap masking were used in many hospitals, but the results were not effective. This article focuses on the etiology of corneal fistula. We hope that it will be helpful to patients. Most corneal fistulas are caused by perforated corneal ulcers or perforating trauma. There are four or five types of fistulas, but there are two main types of fistulas: one is a corneal ulcer punctured directly in front of the pupil, which can be filled with exudate or repaired by slowly proliferating connective tissue because there is no iris prolapse. When the anterior chamber is re-formed, the exudate filling the perforated area breaks down due to the pressure of the atrial water, and the connective tissue does not easily proliferate, so corneal fistula occurs. In another case, the corneal perforation is located outside of the pupil area and heals with an embedded iris, with minimal scar tissue and lax arrangement, leaving gaps. Another etiology of corneal fistula is damp heat of the wind chakra, also known as damp heat of the black eye, which is one of the common symptoms of ophthalmology. It is the Western equivalent of viral keratitis, vesicular keratitis, keratoconjunctivitis, mycotic corneal ulcer, and pus accumulation in the anterior chamber. Wind-wheel damp-heat is a disease of the black eye. The disease starts slowly, has a long course, and is prone to recurrent attacks. When damp-heat accumulates in the liver and gallbladder and fumigates the wind chakra, the black eye becomes opacified; when dampness is obscene, the opacity is grayish and filthy; when damp-heat fumigates the Huangren and Shenshui, the pus accumulates and becomes pus, the Shenshui is cloudy and the pus accumulates and is as white as paste. Dampness is heavy and sticky, and sticks with heat, so that the disease lingers and recurs.