Reproducibility of optic disc measurements with computerized analysis of stereoscopic video images
J. Caprioli, U. Klingbeil, M. Sears and B. Pope
Computerized digital image analysis of the optic nerve head was performed
using a simultaneous stereoscopic video camera system to provide rapid,
quantitative measurements of optic nerve head topography. Determination of
the variability of the measurements is required to estimate the magnitude
of optic nerve change over time that can be reliably detected. Total
variability, operator variability, and interoperator variability were
studied. Total variability was assessed by analyzing ten sets of video
recordings made in each of seven eyes of seven normal subjects, and in
seven eyes of seven patients with glaucoma. The median coefficients of
variation for measurements of total variability in glaucoma patients were
as follows: vertical disc measurement, 1.4%; horizontal disc measurement,
2.1%; disc area, 1.9%; vertical cup/disc, 3.9%; horizontal cup/disc, 3.3%;
disc rim area, 7.5%; and volume, 7.6%. Operator and interoperator
variabilities were considerably smaller in magnitude.
