Factors Associated with Vision Outcomes in Microbial Keratitis - a Multisite Prospective Cohort Study.

Abstract

Objective: To investigate factors associated with 90-day visual acuity in microbial keratitis (MK) patients.

Design: This multicenter prospective cohort study recruited patients with MK from the United States (US) and India from July 23, 2020 through May 1, 2024, and followed them for up to 90 days.

Participants: Individuals 15 years and older with MK greater than 2mm² in stromal infiltrate area without study exclusion criteria of prior corneal surgery or gluing, impending corneal perforation or keratoplasty, no light perception vision, or current pregnancy or incarceration.

Methods: Data on sociodemographic features, health and ocular history, symptoms, and clinical measures were gathered. Best-corrected visual acuity (BCVA) was measured in the affected eye at initial and 90-day visits with carried forward BCVA for those healed prior to 90 days. Features were summarized overall and by site. Site-stratified multivariable linear regression models were used to investigate associations with 90-day logMAR BCVA.

Main outcome measures: 90-day logMAR BCVA.

Results: There were 479 participants analyzed after exclusions (n=31) and participants without a final BCVA (n=52). Participants had an average 90-day BCVA of 1.36±1.40 logMAR units (Snellen approximate 20/460 ± 14.0 lines) in the US and 0.70±0.99 (Snellen approximate 20/100 ± 9.9 lines) in India (P<0.0001). For the US cohort, worse 90-day logMAR BCVA was associated with worse presenting BCVA (β=0.05 logMAR unit increase in 90-day logMAR BCVA per 0.1 logMAR unit increase in presenting BCVA, P<0.0001), longer time until presentation (β=0.01 per day, P<0.0001), no contact lens use (β=0.46, P=0.0131), and larger stromal infiltrate area (β=0.02 per 1mm² increase in area, P=0.0082 for bacterial ulcers; β=0.10 per 1 mm² increase in area, P=0.0002 for fungal; interaction p=0.0017). For the India cohort, worse 90-day logMAR BCVA was associated with worse presenting BCVA (β=0.04 logMAR unit increase in 90-day logMAR BCVA per 0.1 logMAR unit increase in presenting BCVA, P<0.0001), longer delays to presentation (β=0.03 per day, P=0.0004), diabetes mellitus (β=0.41, P=0.0019), hypopyon (β=0.27, P=0.0083), no recent ocular trauma (β=0.21, P=0.0370), and larger stromal infiltrate area (β=0.03 per 1mm² increase in area, P<0.0001 for fungal; interaction p=0.0001; nonsignificant β=-0.02 per 1mm² increase in area, P=0.07 for bacterial ulcers;).

Conclusions: Initial vision, longer time until presentation, and larger stromal infiltrate size conferred risk for worse 90-day BCVA in both cohorts, while other factors were unique. Systems to mitigate care delays and support communities to access care are needed so that clinicians can intervene and improve vision outcomes.