Reproducibility of macular ganglion cell–inner plexiform layer thickness in normal eyes determined by two different OCT scanning protocols

BACKGROUND: To investigate the reproducibility of macular ganglion cell-inner plexiform layer (GCIPL) thickness measurement in normal eyes determined by different operators and two different raster scanning protocols of Cirrus high-definition optical coherence tomography (HD-OCT). METHODS: One hundred and two eyes of 102 normal subjects were scanned three times using Cirrus HD-OCT with Macular Cube 512 × 128 protocol by two operators, respectively. Three extra scans were obtained using Macular Cube 200 × 200 protocol. The average, minimum, superotemporal, superior, superonasal, inferonasal, inferior, and inferotemporal GCIPL thickness was measured. The reproducibility of the measurements was evaluated with intraclass correlation coefficients (ICC) and coefficients of variation (CoV). RESULTS: The intra-operator ICCs of macular GCIPL thickness were >0.875; and the inter-operator ICCs were 0.882 to 0.991. The intra-protocol ICCs of Macular Cube 512 × 128 and 200 × 200 protocol were 0.953 to 0.987 and 0.953 to 0.991, respectively; and the inter-protocol ICCs were 0.876 to 0.991. All CoVs were <1.5%. CONCLUSIONS: Cirrus HD-OCT can measure macular GCIPL thickness in normal eyes with excellent reproducibility. The measurements determined by Macular Cube 512 × 128 and 200 × 200 protocol were highly consistent and both protocols were eligible for macular GCIPL thickness measurement.