Association of Postfungal Keratitis Corneal Scar Features With Visual Acuity.

Importance Corneal opacity is a leading cause of visual impairment worldwide; however, the specific features of corneal scars, which decrease visual acuity, have not been well characterized. Objective To investigate which features of a postfungal keratitis corneal scar contribute to decreased visual acuity after an episode of infectious keratitis and evaluate whether any corneal features may be used as outcomes for clinical trials. Design, Setting, and Participants In this ancillary, prospective cross-sectional study, a subset of study participants treated for fungal keratitis (n = 71) as part of the Mycotic Ulcer Treatment Trial I (MUTT I) underwent best spectacle-corrected visual acuity (BSCVA) and best contact lens-corrected visual acuity examination, Scheimpflug imaging, and anterior segment optical coherence tomography at a referral hospital in India approximately 2 years after enrollment. Data were collected from December 3, 2012, to December 19, 2012, and analyses were performed from December 2, 2013, to October 2, 2019. Main Outcomes and Measures Linear regression models were used to evaluate the importance of various corneal features for BSCVA and to assess whether these features could be used to differentiate the 2 treatment arms of the MUTT I trial. Results Seventy-one patients (42 men [59.1%]; median age, 48 [range, 39-60] years) were examined at a median (IQR) time of 1.8 (1.4-2.2) years after enrollment. The mean (SD) logMAR BSCVA was 0.17 (0.19) (Snellen equivalent, 20/32). In multivariable linear regression models, BSCVA was most associated with irregular astigmatism (1.0 line of worse BSCVA per 1-line difference between BSCVA and contact lens visual acuity; 95% CI, 0.6-1.4) and corneal scar density (1.5 lines of worse vision per 10-unit increase in the mean central corneal density; 95% CI, 0.8-2.3). The thinnest point of the cornea was the metric that best discriminated between the natamycin- and voriconazole-treated ulcers in MUTT I, with 29.3 mu m (95% CI, 7.1-51.6 mu m) less thinning in natamycin-treated eyes. Conclusions and Relevance Both irregular astigmatism and corneal scar density may be important risk factors for BSCVA in a population with relatively mild, healed fungal corneal ulcers. The thinnest point of the corneal scar may be a cornea-specific outcome that could be used to evaluate treatments for corneal ulcers. This cross-sectional study investigates which features of a typical postfungal keratitis corneal scar are most associated with vision loss and evaluates the use of corneal imaging metrics as cornea-specific outcomes for clinical studies. Question Which features of a postfungal keratitis corneal scar contribute most to vision loss? Findings In this ancillary cross-sectional study of a subset of 71 patients treated for fungal keratitis in the Mycotic Ulcer Treatment Trial I, irregular astigmatism and scar density were the features most strongly associated with vision loss. The thinnest point of the cornea was the metric that best discriminated between the natamycin- and voriconazole-treated ulcers. Meaning The findings of this study suggest that irregular astigmatism, scar density, and the thinnest point of the cornea may be meaningful cornea-specific metrics that could be used as outcomes in clinical research.