Table 5

Intra (within) centre validity for C/D ratio (direct clinical and photographic measurements)

Groups comparedNoMean difference95% CI for
mean difference
TL as %
of range
Crude ICCAdjusted ICC
C/D ratio:
RCRSv Obs 1 R381−0.15−0.14, −−0.040.39
RCRSv Obs 1 L384−0.15−0.14, −
RCRSv Obs 2 R381−0.15−0.13, −
RCRSv Obs 2 L384−0.10−0.08, −
Obs 1v Obs 2 R3810.050.04,
Obs 1v Obs 2 L3840.050.03,
  • RCRS = research clinic reference standard observation; Obs 1 = stereo photograph assessment by first observer; Obs 2 = Stereo photograph assessment by second observer; R = right eye; L = left eye; SD = standard deviation of paired differences; CI = confidence interval (for the mean); TL = tolerance limit for change; ICC = intraclass correlation coefficient.