Comparative Analysis of Contact Lens-related Bacterial Keratitis According to Culture Positivity: A 25-year Retrospective Study

Purpose: This study investigated the microbiological profile and clinical characteristics of culture positive (CP) contact lens -related bacterial keratitis (CLBK) and compared them to culture negative (CN) cases.Methods: We retrospectively analyzed 142 CLBK patients hospitalized between January 1998 and December 2022. The CP and CN groups consisted of 79 eyes (100 isolates) and 63 eyes, respectively. We investigated the microbiological profile in the CP group and compared the epidemiology, predisposing factors, clinical characteristics, and treatment outcomes between the CP and CN groups. Poor treatment outcomes were defined as a final best-corrected visual acuity (BCVA) <= 0.5, worsened BCVA after treatment, or the need for surgical intervention. We evaluated the risk factors for poor treatment outcomes in the entire cohort through two-proportional Z-test analysis.Results: In CP group, gram-negative bacteria accounted for 85%, and common isolates were Pseudomonas (27%) and Serratia (26%) species. There were significant differences in mean age (27.0 years vs. 33.8 years, p = 0.009) and a history of therapeutic bandage contact lens wear (13.9% vs. 28.6%, p = 0.031) between the CP and CN groups. However, there were no significant differences in symptom duration, prior use of topical antibiotics, sleeping with wearing CL, epithelial defect size, hypopyon, and poor treatment outcomes. Significant risk factors for poor treatment outcomes in the entire group included deep infiltration (Z = 2.88), epithelial healing time >= 7 days (Z = 2.30), initial BCVA < 0.1 (Z = 2.20), over date use of contact lens (Z = 2.10), and epithelial defect size >= 5 mm2 (Z = 2.05).Conclusions: There were no significant differences in clinical characteristics and treatment outcomes between the CP and CN groups. Poor initial clinical findings and over date use of contact lens were associated with poor treatment outcomes in both groups.