Test–retest variability and effect of signal strength on retinal nerve fibre layer thickness measurement in Cirrus optical coherence tomography
| Test–retest variability (μm) | Effect of signal strength* | |
| Mean retinal nerve fibre layer | 3.7 | 0.90 (p<0.001) |
| Quadrant | ||
| Superior | 7.9 | 1.33 (p<0.001) |
| Nasal | 7.0 | 0.41 (p<0.001) |
| Inferior | 6.4 | 1.31 (p<0.001) |
| Temporal | 4.9 | 0.44 (p<0.001) |
Values from analysis of covariance in a randomised block design with signal strength as a covariate.
* Regression coefficient and p value in parentheses.