DEC 02, 2015
By Charles Lin, MD
Cornea/External Disease
Topical treatment for fungal keratitis remains a complicated landscape with conflicting results from clinical trials. Voriconazole has largely been considered superior for treating fungal infections over natamycin in part due to better ocular penetration and experimental data. However, an April 2013 study in JAMA Ophthalmology (Mycotic Ulcer Treatment Trial, MUTT) suggested inferior efficacy of voriconazole in fungal keratitis. This more recent study in the British Journal of Ophthalmology adds to the growing body of literature that suggests natamycin may be more effective for treating fungal keratitis than voriconazole.
The randomized, double-masked trial included 118 patients (118 eyes) in India treated with topical 1% voriconazole or 5% natamycin for fungal keratitis. Of the 58 patients treated with natamycin, 89.2% had healed or resolving ulcers compared with 66.6% of the 51 patients treated with voriconazole (P=0.005). Compared to the voriconazole group, patients treated with natamycin also had significantly improved vision at the final visit (P=0.01).
Several previous studies also indicate that some fungal types are more susceptible to antifungal drugs. Subgroup analyses from this study agree with prior in vitro data that the Fusarium species is more vulnerable to natamycin. The final visual acuity in the natamycin group was significantly better in patients with Fusarium keratitis (P=0005) compared to Aspergillus keratitis (P=0.714). However, the authors acknowledge that the subgroup analysis considered a small group of patients; 7 with Aspergillus, and 13 with Fusarium.
The results from this study along with the MUTT trial suggest that topical voriconazole is best used as an adjunctive therapy when monotherapy with natamycin is ineffective. The authors also note that 2 patients in the natamycin group required keratoplasty, which suggests further research is required to find more effective antifungal drugs.