Evaluating the clinical relevance and reliability of outer retinal band length on optical coherence tomography in retinal disease: a cross-sectional study

Objectives Hyper-reflective outer retinal band (HORB) disruptions are reported across a range of retinal disease, yet a reliable, easily implemented assessment method and thorough evaluation of their association to retinal disease is lacking. The purpose of the study was to assess the reliability of using magnitude estimation to evaluate HORB length and determine its association to visual acuity and retinal disease. Design Cross-sectional, retrospective study. Setting Patients attending a secondary eye care clinic in Sydney, Australia. Participants 2039 unique consecutive patients were screened for inclusion between 2 November and 18 January 2021, and 600 were included in the study population. Patients were included if they were referred from primary care, presented for an initial, comprehensive eye examination during the study period, imaged with optical coherence tomography during their visit and over 18 years of age. Primary outcome Reliability of HORB length estimations and associations to clinical outcomes. Results Intragrader (intraclass correlation coefficient, ICCfovea=0.81; ICCworst=0.91) and intergrader (ICCfovea=0.78-0.79; ICCworst=0.75-0.88) agreement of HORB length was good to excellent. HORB length was significantly associated with age (p<0.001, beta=-0.22 to -0.24) and refractive error (p<0.001, beta=0.12-0.16) at all B-scan locations. Visual acuity (p=0.001, beta=-0.13) was associated with the primary outcome for foveal B-scans and eccentricity (p=0.002, beta=-0.13) and device type (p=0.002, beta=0.13) for non-foveal B-scans. Glaucoma was associated with HORB length on univariate analysis (p=0.05-0.06, beta=-0.08); however, multivariate analysis revealed no significant association between HORB length and retinal disease. Conclusion HORB length is reliably assessed using magnitude estimation and may be useful as a surrogate biomarker of visual acuity. Several factors affect HORB length estimations, which may contribute to the lack of association to retinal disease and highlights the need for covariable adjustment when examining HORB disruptions.