This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
[{'content': 'Topical antifungal agent used in keratomycosis is: \nSelect and explain. \nA. Silver sulfadiazine, B. Natamycin, C. Ketoconazole, D. Flucytosine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Fungal keratitis tends to occur after corneal injury involving plant material or in an agricultural setting, in eyes with chronic ocular surface disease, and increasingly in contact lens wearers. Signs: It is usually an indolent process, with the cornea characteristically having multiple stromal abscesses and relatively little epithelial loss. Intraocular infection is common. Investigations: Corneal scrapings should be cultured on media suitable for fungi whenever the history or corneal appearance is suggestive of fungal disease. Diagnosis is often delayed and treatment is difficult. Treatment: Natamycin 5%, amphotericin 0.1-0.5%, and voriconazole 1% are the most commonly used topical agents. Systemic imidazoles may be helpful. Corneal grafting is often required. Ref: Riordan-Eva P. (2013). Chapter 7. Disorders of the Eyes & Lids. In M.A. Papadakis, S.J. McPhee, M.W. Rabow (Eds), CURRENT Medical Diagnosis & Treatment 2013.', 'role': 'assistant'}]