Outcomes of therapeutic penetrating keratoplasty in Pythium insidiosum keratitis managed with a combination of antibiotics

Purpose: To describe the clinical outcomes of therapeutic penetrating keratoplasty (TPK) in patients with Pythium insidiosum keratitis following treatment with anti-pythium therapy (APT) consisting of linezolid and azithromycin. Methods: A retrospective review of medical records from May 2016 to December 2019 of patients with P. insidiosum keratitis was carried out. Patients who were treated with APT for a minimum of 2 weeks and then subsequently underwent TPK were included in the study. Data on demographic characteristics, clinical features, microbiology characteristics, and intraoperative details, postoperative outcomes were documented. Results: A total of 238 cases of Pythium keratitis were seen during the study period and 50 cases that satisfied the inclusion criteria were included. The median of the geometric mean of the infiltrate was 5.6 mm (IQR 4.0-7.2 mm). The patients received topical APT for a median of 35 days (IQR 25-56) prior to surgery. The most common indication of TPK was worsening keratitis (41/50, 82%). No recurrence of infection was observed. An anatomically stable globe was noted in 49/50 eyes (98%). The median graft survival rate was 2.4 months. A clear graft was present in 10 eyes (20%) with a final median visual acuity of 20/125 after a median follow-up period of 18.4 months (IQR 11-26 months). Graft size of less than 10 mm [OR: 5.824 (CI:1.292-41.6), P = 0.02] was found to be significantly associated with a clear graft. Conclusion: Performing TPK following the administration of APT has good anatomical outcomes. A smaller graft of <10 mm was associated with a higher chance of graft survival.