Agreement between clinicians and an image analyzer in estimating cup-to-disc ratios
R. Varma, G. L. Spaeth, W. C. Steinmann and L. J. Katz
William A. and Anna V. Goldberg Glaucoma Service and Research Laboratory, Wills Eye Hospital, Thomas Jefferson University, Philadelphia, PA 19107-5599.
We studied optic disc photographs of 35 eyes to determine the level of
agreement between estimates of vertical and horizontal cup-to-disc ratios
(CDRs) provided by two clinicians and estimates of these ratios obtained
using an image analyzer. We also evaluated the agreement of each clinician
with himself and with the other clinician to provide a relative standard by
which to judge agreement between the clinicians and the image analyzer.
Agreement between the clinicians and the image analyzer was moderate.
Differences of more than 0.2 disc diameters (DD) between the CDR estimates
of clinicians and those obtained using the image analyzer were limited to
discs having small (CDR of 0.4 DD or lower) or very large (CDR of 0.9 DD or
higher) cups. The clinicians' agreement with themselves and with each other
was substantial to near perfect.
