Therapeutic Exploratory Study of Comparing Natamycin and Voriconazole to Treat Fungal Corneal Ulcer

Fungal ulcers tend to have very poor outcomes with the most common treatments, amphotericin B and natamycin. There has been only a single randomized trial of anti-fungal therapy for fungal ulcers and no new medications have been approved by the FDA since the 1960s. There are studies that indicate that the newer triazoles, such as voriconazole, are more effective in vitro against filamentous fungi such as Aspergillus spp., a common cause of fungal keratitis1-3. Despite a number of case reports and in vitro studies, there has been no systematic attempt to determine whether it is more or less effective clinically than natamycin, the only commercially available FDA-approved agent. There is little data available for physicians to make an informed, evidence-based decision on choice of antifungal.

We evaluated whether voriconazole is a superior treatment to natamycin for filamentous fungal keratitis in a randomized, masked, controlled trial. This is a therapeutic exploratory study to investigate the safety and feasibility of conducting a larger study and to generate preliminary data. The primary outcome is visual acuity at 3 months from enrollment. A subset of patients will be followed at 4 years from enrollment.

Inclusion criteria

• Presence of a corneal ulcer at presentation
• Evidence of filamentous fungus on KOH (or Giemsa or any other stain) or culture
• The patient must be able to verbalize a basic understanding of the study after it is explained to the patient, as determined by physician examiner. This understanding must include a commitment to return for follow-up visits.
• Willingness to be treated as an in-patient or to be treated as an out-patient and come back every 48-72 hours to receive fresh medication for 3 weeks
• Appropriate consent

Exclusion criteria

• Overlying epithelial defect < 0.5 mm at its greatest width at presentation
• Impending perforation
• Evidence of bacteria on Gram stain at the time of enrollment
• Evidence of acanthamoeba by stain
• Evidence of herpetic keratitis by history or exam
• Corneal scar not easily distinguishable from current ulcer
• Age less than 16 years (before 16th birthday)
• Bilateral ulcers
• Previous penetrating keratoplasty in the affected eye
• Pregnancy (by history or urine test) or breast-feeding (by history)
• Acuity worse than 6/60 (20/200) in the fellow eye (note that any acuity, uncorrected, corrected, pinhole, or BSCVA 6/60 or better qualifies for enrollment)
• Known allergy to study medications (antifungal or preservative)
• No light perception in the affected eye
• Not willing to participate