Volumetric reproducibility of optic disc variables measured by TopSS
| Variable | SD | CV (%) |
|---|---|---|
| Contour variation (mm) | 0.039 | 8.3 |
| Mean contour depth (mm) | 0.012 | 7.3 |
| Cup shape | 0.028 | 7.9 |
| Effective area (mm2) | 0.047 | 3.9 |
| 1/2 depth area (mm2) | 0.062 | 6.8 |
| C/D ratio† | 0.019 | 4.0 |
| NRRA‡ (mm2) | 0.057 | 4.7 |
| Volume above (mm3) | 0.017 | 8.9 |
| Volume below (mm3) | 0.023 | 4.0 |
| 1/2 depth volume (mm3) | 0.018 | 8.3 |
| Average depth (mm) | 0.019 | 4.3 |
| Maximum depth (mm) | 0.049 | 5.0 |
| Average slope (degree) | 1.225 | 2.9 |
| Maximum slope (degree) | 0.829 | 1.4 |
↵CV = coefficient of variation; †C/D = cup/disc; ‡NRRA = neuroretinal rim area.