Repeatability and Reproducibility of Macular Hole Size Measurements Using Optical Coherence Tomography

The purpose of this study was to assess the repeatability and reproducibility of measuring the minimum linear diameter (MLD) of macular holes (MHs) using horizontal linear and radial scan modes in optical coherence tomography (OCT). Patients with concurrent sets of radial and horizontal linear OCT volume scans were included. The MLD was measured twice in both scan modes by six raters of three different experience levels (groups). Outcome measures were the reliability and repeatability of MLD measurements. Fifty patients were included. Mean MLD was 317.21(+/- 170.63) mu m in horizontal linear and 364.52 (+/- 161.71) mu m in radial mode, a difference of 47.31 (+/- 26.48) mu m (p < 0.001). In the radial scan mode, MLD was identified within 15 degrees of the horizontal meridian in 27% and within 15 degrees of the vertical meridian in 26.7%, with the remainder (46.3%) in oblique meridians. The intra-group coefficients of repeatability (CR) for horizontal linear mode were 23 mu m, 33 mu m and 45 mu m, and for radial mode 25 mu m, 44 mu m and 57 mu m for groups 1, 2 and 3, respectively. The inter-group CR, taking group 1 as reference standard for groups 2 and 3, were 74 mu m and 71 mu m for the linear mode, and 62 mu m and 78 mu m for radial mode. The radial mode provides good repeatability and reliability for measurement of MLD. In a majority of cases the MLD does not lie in the horizontal meridian and would be underestimated using a horizontal OCT mode.