Purpose:
To determine the repeatability of Cirrus HD-OCT retinal nerve fiber layer (RNFL) measurements on normal eyes with and without tracking.
Methods:
Fifteen (15) in-house volunteers with no known retinal pathology were imaged four times in two sessions with the Optic Disc 200x200 scan protocol, using a Cirrus instrument with prototype tracking software to allow capture of motion-free SD-OCT images. Two additional Optic Disc 200x200 scans were also obtained without tracking in each session. The boundaries of the RNFL were automatically segmented using algorithms available in the Cirrus HD-OCT, software version 6.0. The center of the optic disc was also automatically segmented and TSNIT profiles were extracted from the RNFL segmentation based on the optic disc center. The overall average RNFL thickness and the RNFL thickness over four quadrants were analyzed. Analysis of variance (ANOVA) was used to determine repeatability standard deviation (SD) for each of the parameters. Coefficient of variability (COV) was calculated as the SD divided by the mean measurement.
Results:
Table 1 shows the coefficient of variability (COV) for each parameter, with and without tracking. It was seen that the repeatability of average RNFL thickness improved with tracking. Three out of the four quadrants showed improvements in repeatability.
Conclusions:
Tracking improves the repeatability of Cirrus HD-OCT RNFL measurements.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical • optic disc