Variability of depth measurements of the optic nerve head and peripapillary retina with computerized image analysis
L. Dandona, H. A. Quigley and H. D. Jampel
Wilmer Ophthalmological Institute, Johns Hopkins University, School of Medicine, Baltimore, Md 21205.
Computerized topographic mapping of 10 repeated fundus images of one eye
each in 10 healthy subjects and in 10 subjects with elevated intraocular
pressures (IOPs) was performed with the Humphrey Retinal Analyzer. The
variability of depth measurements at 400 to 650 individual locations in the
optic nerve head and peripapillary retina was evaluated. The average size
of the 95% confidence intervals for individual depth measurements for
healthy subjects and those with elevated IOPs were 166 and 232 microns in
the optic nerve head and 205 and 261 microns in the peripapillary retina,
respectively. Variability was significantly less for healthy subjects than
for those with elevated IOPs. Variability was significantly greater for
depth measurements in the peripapillary retina than for measurements in the
optic head. Knowledge about variability of individual depth measurements is
useful for proper interpretation of computerized topographic mapping to
detect retinal nerve fiber damage.
