Various pathogenic factors put the conjunctiva in a damaged state, causing lesions that lead to edema called conjunctival edema; if not properly taken care of, it can cause keratitis and corneal ulcers in mild cases, or infection or even blindness in severe cases. What is the differential diagnosis of conjunctival edema and corneal ulcers? If conjunctival edema is not properly cared for, it can cause keratitis and corneal ulcers in the mild cases, or infection or even blindness in the severe cases. The diagnosis of clinical examination includes the following two points: 1, the diagnosis of corneal disease needs to be based on the medical history whether there are symptoms of corneal irritation and history of trauma, whether local and systemic corticosteroids have been used; whether there are chronic lacrimal sacculitis, entropion and other eye diseases and related systemic diseases. 2.For severe irritation, especially in children, surface anesthetic drops can be applied before examination. For those who are at risk of perforation, do not compress the eye during examination. For superficial corneal damage, fluorescein staining can be easily detected, and the site and shape of corneal lesions can be more easily detected by using a magnifying glass or slit lamp. If necessary, corneal perception examination and tear secretion function examination are performed. Keratitis is a common type of corneal disease, divided into two categories: ulcerative keratitis, also known as corneal ulcer, and non-ulcerative keratitis, or deep keratitis. It is caused by different factors of internal and external causes. Inflammation caused by corneal trauma, bacterial and viral invasion of the cornea. The affected eye has a foreign body sensation, stinging pain or even burning sensation. Mixed congestion on the surface of the bulbar conjunctiva with photophobia, lacrimation, visual impairment and increased secretion. The corneal surface is infiltrated with ulcer formation. Ulcerative keratitis, also known as corneal ulcer, is overwhelmingly caused by exogenous factors, that is, inflammation that occurs when infectious agents invade the corneal epithelial cell layer from outside.