Marginal ulcerative keratitis, also known as corneal ulcer, is overwhelmingly due to exogenous factors, i.e., inflammation that occurs when infectious causative agents invade the corneal epithelial cell layer from outside. The basic principle in the treatment of limbal ulcerative keratitis is to take all effective measures to control the infection quickly, to achieve early cure, and to minimize the sequelae of keratitis. Since most ulcerative keratitis is due to external causes, it is important to remove the external causes and eliminate the pathogenic microorganisms. So, what are the preventive measures for marginal ulcerative keratitis? The following is a brief introduction. 1, hot compress: make eye blood vessels dilate, lift congestion, while promoting blood flow, enhance resistance and nutrition, so that the ulcer gets rapid recovery. 2.Rinsing: If there are more secretions, use saline or 3% boric acid solution to rinse the conjunctival sac 3 or more times a day in order to flush out secretions, necrotic tissue, bacteria and toxins produced by bacteria. This will not only reduce the factors of infection expansion, but also ensure that the concentration of the topical medication does not diminish. 3, dilated pupil: a. Atropine is the main and commonly used drug, the concentration of 0.25-2% solution or ointment, 1 to 2 times a day drops, coating (after drops pay attention to pressure on the tear sac, so as to avoid excessive absorption of the solution by the mucosa, causing poisoning). b. For simple corneal ulcers or irritation symptoms are not significant can not be used, for irritation symptoms are significant and the potential will be perforated ulcers must be used. This drug has a dual role in the treatment of corneal ulcers; on the one hand, it rests the pupillary sphincter and ciliary muscles, and on the other hand, it prevents and treats iridocyclitis and its consequences. Furthermore, it also has a pain-relieving and analgesic effect as the spasm of the intraocular muscles is released.