Clinical Features of Microbial Keratitis Associated with Reduced Final Visual Acuity

Abstract

Purpose : Microbial keratitis is an ophthalmologic emergency that affects all age groups and can lead to permanent loss of visual acuity (VA).
The aim of our study is to identify predisposing factors for a poor visual outcome among patients with resolved microbial keratitis.

Methods : This was an ambispective cohort analysis of patients with known diagnosis of microbial keratitis from January 2009 to December 2016. We recorded demographic data, predisposing factors, microbiological culture status, ulcer size, VA at presentation, and VA at last visit to a maximum follow-up of 6 months.

Results : Inclusion of 302 eyes with diagnosis of microbial keratitis was carried out. The age (mean ± standard deviation) was 39.95±22.85 years and 53.64% (n= 162) of the cases were woman. The VA expressed the in logarithm of the minimal angle of resolution (logMAR) at presentation (1.38±0.88) improved significantly (p=0.0001), when compared with the VA at last visit (1.07±0.94). Microbiological cultures were performed in 97.72% (n=280) of the cases; 64.29% (n= 180) were positive. In the eyes with positive microbiological culture, VA at last visit was worse than in cases with negative culture (p=0.008). Bacterial keratitis was the most frequent diagnosis (n= 95, 52.8%). Only the eyes with bacterial keratitis presented a significant improvement (p=0.024) when comparing initial VA (1.47±0.85) and final VA (1.16±0.93). In contrast, fungal keratitis showed no improvement (p=0.776) after analysis of initial VA (1.46±0.74) and VA at the last visit (1.41±1.1). Larger ulcer size was correlated with a worse final VA (p=0.002, rho=0.204). Predisposing factors such as contact lens use, trauma with organic or non-organic matter did not show a statistically significant correlation with worse final VA.

Conclusions : Despite a significant improvement in VA after resolution of microbial keratitis, the degree of visual impairment is still considerable. A lack of VA improvement was evidenced for fungal keratitis. Larger ulcer size and positive microbiological cultures were associated with worse final VA. Efforts should be taken to enhance patient education, avoid predisposing factors and identify prognostic clues to improve visual prognosis.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.