Determination of surgical outcomes with a novel formulation of intrastromal natamycin in recalcitrant fungal keratitis: A pilot study

Purpose: To evaluate the outcomes of water-soluble intrastromal natamycin (IS-NTM) as an adjunct therapy for recalcitrant fungal keratitis. Methods: This was a prospective interventional pilot study in the setting of a tertiary eye-care center. Twenty eyes of 20 consecutive patients with microbiologically proven recalcitrant fungal keratitis (ulcer size >2 mm, depth >50%, and not responding to topical NTM for 2 weeks) were recruited. The selected patients were injected with a novel composition of IS-NTM (10 ug/0.1 mL, soluble natamycin) prepared aseptically in the ocular pharmacology department. All the patients continued using topical NTM suspension 5% 4-hourly until the ulcer healed. Repeat injections were undertaken after 72 h depending on the clinical response and all the patients were followed till 6 months. Results: The mean age of the patients was 40.42 ± 10.09 years. The mean duration of the presentation was 20.8 ± 5.1 days. The most commonly isolated organisms were Aspergillus sp. (12/20, 60%) and Fusarium sp. (8/20, 40%). No patient had iatrogenic perforation or precipitate formation after IS-NTM injection. The overall cure rate with IS-NTM was 95% (19/20 patients). The number of patients who healed with the 1st, 2nd, and 3rd injection was 13, 5, and 1, respectively. One (5%) had no response to treatment and was subjected to penetrating keratoplasty. The average time taken for the resolution of the epithelial defect, stromal infiltrates, and hypopyon was 34 ± 5.2 days, 35.3 ± 6.4 days, and 15 ± 2.5 days. Healing with deep vascularization and cataract was noted in 6/19 eyes (31%) and 13/19 eyes (68.42%), respectively. Conclusion: Intrastromal injection of a novel formulation of NTM holds a promising role as adjunctive therapy to topical NTM in the management of recalcitrant filamentous fungal keratitis. The preliminary results are encouraging and further studies are required to validate the results