☆ What is fungal keratitis? Fungal keratitis is an infectious keratoconus caused by a pathogenic fungus that has a high rate of blindness. Fungal keratitis is clinically difficult to diagnose, easily misdiagnosed, and often results in blindness due to improper treatment. Normally, fungi do not invade the normal cornea, but when there is ocular trauma, long-term topical antibiotic use, corneal inflammation and dry eye, non-pathogenic fungi may become pathogenic and cause secondary fungal infections of the cornea. The common pathogenic fungus is Aspergillus, followed by Fusarium, Candida albicans, Cephalosporium and Streptomyces. Xiamen University Eye Center Ocular Surface and Corneal Disease Dong Nuo Fungal keratitis is not uncommon. The incidence is high in the summer and autumn agricultural seasons. In terms of age and occupation, it is mostly seen in young adults, the elderly and farmers. The morphology of corneal ulcers varies depending on the causative organism. Fungal keratitis can appear as immune rings, satellite foci, pseudopods, mycelial mosses, anterior chamber pus accumulation and endothelial spots. How is a corneal ulcer diagnosed? The basic principle of treating corneal ulcers is to take all effective measures to control the infection quickly, to strive for early cure, and to minimize the sequelae of keratitis. Since most ulcerative keratitis is due to external causes, it is extremely important to remove the causative external causes and eliminate the causative microorganisms. To help diagnose the cause, a smear should be taken from the proceeding edge of the corneal ulcer for bacterial culture and drug sensitivity testing (and mycobacterial culture if necessary). However, it is important not to delay treatment by waiting for the test results, but to take the necessary measures immediately. Our hospital carries out in vivo laser confocal microscopy technique (see figure) can effectively and quickly assist in diagnosing whether fungal bacterial infection is present. ☆Why do corneal ulcers cause tearing, eye redness and eye pain? The cornea is rich in sensory nerves and is mainly reached by the ophthalmic branch of the trigeminal nerve via the ciliary nerve. When corneal ulcers occur, inflammatory stimulation of the sensory fibers of the trigeminal nerve can lead to severe eye pain, and patients often complain of photophobia, tearing, pain, and in severe cases, irritation such as eyelid spasm. ☆ Difficulties in the treatment of fungal corneal ulcers? There is a lack of highly effective, broad-spectrum antifungal drugs. Clinical treatment mainly relies on corneal transplantation. However, corneal transplantation faces many problems such as lack of donor corneas, high postoperative immune rejection rate and endothelial failure of implants. What is the recovery of vision from corneal ulcers? A corneal ulcer is bound to affect vision to a greater or lesser extent, especially if the inflammation invades the pupil area. The corneal scar formed after the ulcer heals not only prevents light from entering the eye, but also changes the curvature and refractive power of the corneal surface, so that objects cannot be focused on the retina to form a clear image, thus reducing vision or even causing blindness, and requiring corneal transplantation. The degree of vision involvement depends entirely on the location of the scar. If it is located in the middle of the cornea, even though the scar is small, it affects the vision greatly. ☆ New treatment for corneal ulcers? The effectiveness of corneal collagen cross-linking therapy as a new treatment for infectious corneal disease has been demonstrated in in vitro experiments as well as in clinical applications. The treatment principle is to irradiate corneal collagen fibers impregnated with the photoreceptor riboflavin by UV-A at a wavelength of 370 nm to induce cross-linking of corneal collagen fibers, thereby increasing the mechanical strength of the collagen fibers and their resistance to corneal collagenase, enhancing the biochemical and mechanical stability of the corneal stroma, and thus preventing the progression of infected corneal ulcers. Since its introduction in 2011, we have cured hundreds of patients with difficult infectious corneal ulcers.