Table 4. Pearson’s correlation coefficient R and agreement measurements for the averages of three measurements made by two observers on the nerve-head to fovea distance (NFD) mm. from the center of the nerve-head and the rim of the nerve-head in 30 right eyes (OD) and 30 left eyes (OS).
| Measurement | R | Mean | SDa | 95% limits of agreement and 95% CI | |
| Lower limit & 95% CI | Upper limit & 95% CI | ||||
| Center nerve-head | |||||
| OD | |||||
| Three repeated measurements | 0.961 | −0.029 | 0.098 | −0.222 (−0.283, −0.161) | 0.164 (0.103, 0.225) |
| Single measurement | 0.111 | −0.247 (−0.316, −0.178) | 0.189 (0.120,0.258) | ||
| OS | |||||
| Three repeated measurements | 0.970 | 0.016 | 0.086 | −0.153 (−0.206, −0.099) | 0.184 (0.131, 0.237) |
| Single measurement | 0.098 | −0.176 (−0.236, −0.115) | 0.207 (0.146,0.267) | ||
| Rim nerve head | |||||
| OD | |||||
| Three repeated measurements | 0.923 | −0.164 | 0.145 | −0.447 (−0.536, −0.357) | 0.120 (0.030, 0.209) |
| Single measurement | 0.156 | −0.468 (−0.565, −0.372) | 0.141 (0.045,0.238) | ||
| OS | |||||
| Three repeated measurements | 0.914 | −0.076 | 0.144 | −0.358 (−0.448, −0.269) | 0.206 (0.117, 0.296) |
| Single measurement | 0.152 | −0.374 (−0.468, −0.280) | 0.222 (0.128,0.316) | ||
a
SD for single measurements = √ [(SD difference for average of three measurements)2+ (SD within three measurements of observer 1)2+ (SD within three measurements of observer 2)2].