Predictors of Visual Outcomes in Microbial Keratitis

Abstract

Purpose : Significant variation in microbial keratitis (MK) presentations exists, making it difficult to risk stratify patients for visual outcomes. We performed a multisite prospective cohort study to identify presenting clinical features associated with MK 90-day (90d) visual outcomes.

Methods : We recruited participants at the University of Michigan (UM) and Aravind Eye Care Systems (AECS) in India from July 2020 to April 2023 as part of the Automated Quantitative Ulcer Analysis study. Participants were 15 years or older with MK ≥2mm² in area without prior incisional corneal surgery, corneal glue or bandage contact lens, or Acanthamoeba infection. Participants completed demographic, health history, and eye symptom surveys at presentation. Visual function and ulcer morphology were taken from technician-performed visual acuity (VA) scales and ophthalmologist clinical exams through 90 days. Our primary outcome was 90d best-corrected VA (90d BCVA) using logMAR. We performed site-stratified descriptive statistics and multivariable linear regression with P<0.05 defined as statistically significant. Model results are reported with estimates and 95% confidence intervals (CI).

Results : 313 participants were enrolled (91 UM, 222 AECS). Average 90d BCVA was significantly worse in UM versus AECS participants (1.19 at UM vs 0.65± at AECS; Snellen equivalent 20/310 ±1.3 lines at UM vs 20/89 ± 0.9 lines at AECS; p<0.0001). At UM, worse presenting VA (estimate=0.05 per 0.01 increase in logMAR; CI 0.03,0.07; p<0.0001) and larger epithelial defect area (estimate=0.02 per 1mm²; CI 0.01,0.03; p=0.0004) predicted worse 90d BCVA, while contact lens use (estimate=-0.65; CI -1.10, -0.20; p=0.0055) and longer stromal infiltrates (estimate=-0.20 per 1mm; CI -0.34,-0.07; p=0.0042) predicted better 90d BCVA . At AECS, worse presenting VA (estimate=0.04 per 0.01 increase in logMAR; CI 0.03,0.06; p<0.0001), diabetes (estimate=0.39; CI 0.07,0.71; p=0.0184), and wider stromal infiltrates (estimate=0.11 per 0.1mm; CI 0.02,0.06; p=0.0131) predicted worse 90d BCVA, while ocular trauma (estimate=-0.39; CI -0.62, -0.16; p=0.0008) predicted better 90d BCVA.

Conclusions : Certain presenting clinical features predict worse MK visual outcomes. Some predictive features differed between study sites, suggesting geographic, risk factor, and population differences. Recognizing key regional risk factors can help clinicians to effectively manage MK patients based on visual prognosis.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.