Satellite lesions rarely develop in yeast infections. Although the history and clinical appearance may strongly suggest fungal keratitis, cultures are necessary to confirm your diagnosis. Plate multiple deep scrapings of the lesion on blood agar and Sabouraud media. The culture results should be available in two to three days, although some fungi take up to three weeks to grow. Treatment of fungal keratitis is often difficult because no single agent works against all types of infection.
Treatment often requires six weeks or more of topical therapy.
A standard regimen is to administer natamycin every 30 minutes for the first three to four days, then continue six times a day until the infection resolves. The drug works best for superficial infections, yet can be toxic to the corneal epithelium. Before we had natamycin, amphotericin B was the most widely used drug for fungal infections. It still may be effective in some cases today, but its use is limited by resistance, toxicity and the topical discomfort it can cause. Amphotericin B may be most useful in cases where the infection extends to the intraocular tissues.