Central retinal thickness in a longitudinal cohort in Monrovia, Liberia

To characterize the distribution of central subfield thickness (CST) measured by spectral-domain optical coherence tomography (SD-OCT) in a longitudinal cohort of Ebola virus-seronegative individuals in Liberia.

Longitudinal cohort study.

Close contacts of Ebola virus disease (EVD) survivors enrolled in the PREVAIL III Eye Study in Monrovia, Liberia underwent comprehensive ophthalmic examinations and macular imaging with Cirrus 5000 SD-OCT over five annual study visits. Prior Ebola virus infection was assessed using anti-Ebola virus glycoprotein IgG serology, and seropositive close contacts were excluded. CST measurements and descriptive statistics were analyzed longitudinally. In a post hoc analysis, participants with uveitis or retinal pathology were excluded from analyses characterizing retinal thickness in otherwise healthy eyes. Statistical analyses were conducted using R.

Among 644 seronegative close contacts who underwent baseline ophthalmic evaluation, 181 (28.1%) had complete CST measurements in at least one eye at baseline, increasing to 548 of 594 (92.3%) at the subsequent annual visit and 404 of 407 (99.3%) at the final study visit. Median CST for the overall cohort at baseline was 220.5 μm (interquartile range, 207-234 μm). After excluding participants with uveitis or retinal pathology, median baseline CST was 220 μm, with 5th and 95th percentiles of 190 and 254 μm, respectively. CST distributions remained relatively stable during four years of follow-up, with a median CST of 220 μm in the final year.

CST values in this seronegative cohort from Monrovia were toward the lower end of previously reported Cirrus-based reference distributions. In a subset free of inflammation or retinal pathology, CST showed similar distributions across study visits. These findings highlight the importance of generating local datasets to interpret OCT measurements.