Researchers recently took a closer look at post–fungal keratitis corneal scars to determine what exactly affected vision the most and found irregular astigmatism and scar density were important risk factors for visual acuity, even for those with relatively mild, healed ulcers.

The team evaluated 71 patients from the Mycotic Ulcer Treatment Trial I (MUTT I) approximately 1.8 years after enrollment in the study. They found the mean logMAR best spectacle-corrected visual acuity (BSCVA) was 0.17 (Snellen equivalent 20/32) and it hinged, in part, on the patient’s irregular astigmatism. They noticed 1.0 line of worse BSCVA for each one-line difference between the spectacle correction and contact lens visual acuity.

As for corneal scar density, they found 1.5 lines of worse vision for each 10-unit increase in the mean central corneal density.

Corneal thickness was the most predictive factor of treatment success, with natamycin-treated eyes showing 29.3μm less thinning at the thinnest point.

“The thinnest point of the corneal scar may be a cornea-specific outcome that could be used to evaluate treatments for corneal ulcers,” the researchers concluded in their paper.