Intrastromal Antibiotic Therapy for Recalcitrant Bacterial Keratitis

To evaluate the safety and efficacy of adjunctive intrastromal vancomycin and meropenem for the treatment of recalcitrant bacterial keratitis.

We conducted a single-center, retrospective, non-comparative cohort study of consecutive patients with recalcitrant bacterial keratitis treated at a major tertiary center between January 2022 and April 2026. We included adults with suspected or culture‑proven bacterial keratitis failing topical therapy and meeting inclusion criteria. All underwent corneal scraping and adjunctive intrastromal vancomycin (5 mg/mL) and meropenem (20 mg/mL) using a circumferential barrage technique. Repeat injection at 48 hours was determined by a senior corneal specialist according to clinical response. The primary outcome was clinical resolution. Secondary outcomes included epithelial healing, reinjection, and complications.

Twenty eyes of 20 patients were included. At 28 days, 19/20 eyes (95%) achieved clinical resolution of stromal infiltrate and infection. Epithelial defects were present in 18/20 (90%) at baseline, with size reduction in 15/18 (75%) at early follow-up (median 2 days). Median time to complete epithelial healing was 12 weeks (range 10-16 weeks). Six eyes (30%) required reinjection. One eye progressed to perforation requiring penetrating keratoplasty. No direct injection-related adverse events were observed. Gram-positive organisms predominated (13/20, 65%), with polymicrobial infection in 3/20 (15%) and no growth in 3/20 (15%) cases.

Adjunctive intrastromal antibiotic therapy achieved a high rate of infection resolution in this cohort of recalcitrant bacterial keratitis, with a low complication rate. This approach may be considered in refractory cases or when unable to utilize conventional topical therapy. However, further evaluation of its role is needed in larger comparative studies.