Reproducibility and comparison of retinal thickness and volume measurements in normal eyes determined with two different Cirrus OCT scanning protocols.

PURPOSE: To assess reproducibility and compare raster scanning protocols of Cirrus high-definition optical coherence tomography (Carl Zeiss Meditec, Dublin, CA).
METHODS: Five hundred and twenty-eight computed tomography scans were performed in 17 healthy subjects. Four sessions were performed at each visit including two 200 × 200 and two 512 × 128 macular cube scans per session. The examined eye, observer, and order of scanning protocols in-between each session were randomly chosen. Reproducibility was described with intraclass correlation coefficients, coefficients of variance, intervisit, interrater, intersession intra-, and intersubject standard deviations.
RESULTS: Intraclass correlation coefficients ranged from 80.4% to 97.8% and the coefficients of variance from 0.7% to 2.3% for retinal volume and retinal thickness measurements. Intersubject, intervisit, interrater, intersession, and intrasubject standard deviations ranged from 0 μm to 18.54 μm. Differences in retinal thickness between protocols were small (range 3.55 ± 1.95 μm to 0.81 ± 0.59 μm) but significant for the central (P < 0.0001), the outer superior (P = 0.0036), temporal (P = 0.0026), and nasal subfield (P < 0.0001). Average difference of retinal volume between protocols was 0.05 ± 0.04 mm (P = 0.0001).
CONCLUSION: Both raster scanning protocols of the Cirrus optical coherence tomography showed excellent reproducibility of retinal thickness and volume measures. Significant differences between protocols for retinal thickness in four macula thickness map subfields and for retinal volume were found.