Table 3
Sample size calculations based on the variability data presented in table 2.
| Technique | Parameter | Sample size |
|---|---|---|
| Sample sizes are given based on a two way crossover design using pairwise analysis, a double sided α error of 0.05, and a β error of 0.20 in order to detect a 10% difference between treatment groups. All sample sizes are rounded up to even numbers to allow for balanced randomisation. | ||
| AU, arbitrary units. | ||
| Pneumotonometry | Pulsatile ocular blood flow (µl/min) | 12 |
| Laser interferometry in the macula | Fundus pulsation amplitude (µm) | 4 |
| Colour Doppler imaging in the ophthalmic artery | Peak systolic velocity (cm/s) | 8 |
| End diastolic velocity (cm/s) | 14 | |
| Mean flow velocity (cm/s) | 8 | |
| Colour Doppler imaging in the posterior ciliary arteries | Peak systolic velocity (cm/s) | 18 |
| End diastolic velocity (cm/s) | 18 | |
| Mean flow velocity (cm/s) | 10 | |
| Laser Doppler flowmetry in the macula | FLOW (AU) | 14 |
| VEL (AU) | 8 | |
| VOL (AU) | 12 | |
