Visual outcomes in treated bacterial keratitis: four years of prospective follow-up

Abstract

Purpose: We described the change in visual acuity experienced by eyes successfully treated for bacterial keratitis.

Methods: This was a prospective cohort study of a subset of study participants who had previously enrolled in the Steroids for Corneal Ulcers Trial (SCUT). All study participants had been diagnosed with culture-proven bacterial keratitis before enrollment in SCUT and subsequently were randomized to adjunctive topical corticosteroids or placebo. During SCUT, we monitored study participants at enrollment, 3 weeks, 3 months, and 12 months. We invited a subset to complete a comprehensive eye examination approximately 4 years after enrollment in SCUT. Certified refractionists assessed best spectacle-corrected visual acuity (BSCVA) using the same protocol at each study visit.

Results: We examined 50 SCUT participants at 4 years after enrollment. Among those in this cohort, mean logMAR BSCVA at enrollment was 0.85 (Snellen equivalent, 20/160; 95% confidence interval [CI], 0.71-0.99). On average, visual acuity improved by 2.9 logMAR lines from enrollment to 3 weeks (P < 0.001), 1.2 lines from 3 weeks to 3 months (P = 0.002), and 0.8 lines from 3 to 12 months (P = 0.01). The BSCVA did not change significantly between 12 months and 4 years (0.04-line improvement, P = 0.88). After controlling for visual acuity at enrollment, BSCVA was not significantly different between the corticosteroid and placebo groups at 4 years (P = 0.53).

Conclusions: Cases of bacterial keratitis may continue to demonstrate improvements in visual acuity up to 12 months following diagnosis, but further improvements are unlikely. These findings may guide the appropriate timing of surgical intervention in these patients. (ClinicalTrials.gov number, NCT00324168.).

Keywords: clinical trial; keratitis; long-term; outcomes; prospective; visual acuity.

Figure 1

The BSCVA at five study visits in a subset of participants from the SCUT Trial. The predicted means and 95% CIs are shown for the 47 nonoperated participants who had BSCVA data at the 4-year follow-up visit.

Figure 2

Subgroup analysis of longitudinal BSCVA in a subset of participants from the SCUT Trial. The predicted means and 95% CIs are shown, stratified by (A) enrollment visual acuity, (B) causative organism, (C) presence of cataract at the 4-year follow-up visit, and (D) treatment allocation in SCUT (steroids versus placebo).