Purpose:
To assess the reproducibility of optic nerve head (ONH) parameters measured with Cirrus HD-OCT in glaucomatous eyes.
Methods:
Fifty-five stable glaucoma patients of varying severity were included. One eye of each patient was dilated and scanned 3 times during the initial session to determine the intravisit variability and 1 time on 4 subsequent sessions on different days within 2 months to determine the intervisit variability. The same Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA) was used in all testing sessions by the same operator. The ONH parameters analyzed were the disc area, rim area, cup volume, cup-to-disc area ratio (CDR), vertical cup-to-disc ratio (VCDR), horizontal cup-to disc ratio (HCDR), vertical rim thickness (VRT), and horizontal rim thickness (HRT). These parameters were automatically generated from the Optic Disc 200x200 data by a new Zeiss algorithm (Cirrus ver 5.0). The reproducibility was assessed by intraclass correlation coefficient (ICC), coefficient of variation (COV) and within-subject test-retest (TRT) standard deviation.
Results:
Intravisit and intervisit results were very similar. ICCs were excellent for all ONH parameters and ranged between 95% and 99.4% and between 97.1% and 99.1% for intravisit and intervisit measurements, respectively. CDR had the lowest COV of 1.1% as well as the lowest TRT standard deviation of 0.009 in both intravisit and intervisit measurements. In contrast, VRT and HRT had the highest measured COV and TRT.
Conclusions:
Cirrus HD-OCT produces excellent and very similar reproducibility for both intravisit and intervisit ONH parameters. The best performing measurement was the CDR. Because the ONH analysis software uses a stable reference plane relative to the ONH for delineation of the boundaries around the entire nerve, there is less variability in the ONH parameters. Thus longitudinal monitoring of the ONH may be possible with Cirrus HD-OCT for the assessment of glaucoma progression.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical • optic disc