(A) The mean and standard deviation (SD) of eight measurements of the astigmatism (in dioptres) of six toric backcut contact lens blanks (buttons) by two observers using the keratoscopic astigmatic ruler (observer 1 was a novice, observer 2 an experienced user)
| Observer 1 | Observer 2 | |||||
|---|---|---|---|---|---|---|
| Button | Mean | SD | Mean | SD | ||
| 1 | 1.125 | 0.354 | 1.0 | 0 | ||
| 2 | 2.0 | 0.535 | 2.75 | 0.463 | ||
| 3 | 3.125 | 0.641 | 3.0 | 0.756 | ||
| 4 | 4.25 | 0.707 | 4.125 | 0.835 | ||
| 5 | 5.25 | 0.463 | 4.75 | 0.707 | ||
| 6 | 5.75 | 0.707 | 6.0 | 0 | ||
| No significant difference between observers (p = 1.0, ANOVA). | ||||||
| (B) The mean and standard deviation (SD) of four measurements of the astigmatism of six toric backcut contact lens blanks (buttons) by two observers using the Bausch & Lomb keratometer (observer 1 was a novice, observer 2 an experienced user) | ||||||
| Observer 1 | Observer 2 | |||||
| Button | Mean | SD | Mean | SD | ||
| 1 | 0.312 | 0.217 | 0.625 | 0.27 | ||
| 2 | 1.406 | 0.062 | 1.656 | 0.213 | ||
| 3 | 2.594 | 0.188 | 3.125 | 0.102 | ||
| 4 | 3.531 | 0.461 | 3.781 | 0.062 | ||
| 5 | 4.875 | 0.177 | 4.769 | 0.208 | ||
| 6 | 5.219 | 0.258 | 5.95 | 0.316 | ||
No significant difference between observers (p = 0.953, ANOVA).
Intraclass correlation coefficient of reliability (between observers): KAR, R = 0.898 (95% CI >0.781), B&L, R = 0.975 (95% CI >0.633).
Coefficient of variation: KAR = 0.073, B&L = 0.094.