ABSTRACT
AIM: To evaluate the repeatability and reproducibility of thickness profile measurement of intra-retinal layers determined by an automated algorithm applied to OCT images from Cirrus optical coherence tomography (OCT) instrument.METHODS: In this prospective cross-sectional study,retinal thickness images at 6mm×6mm around fovea were obtained from 86 eyes of 43 normal subjects with Cirrus HD-OCT instrument.The retinal images from patients were analysis by Cirrus automated algorithm GCA software,including ganglion cell layer and inner plexiform layer(GCIPL).During this study,operator A would make 2 times measurements to all patients,after that operator B would make another 2 times measurements by Repeat scan model.All the data,including GCL average thickness,min thickness,12 clock average thickness,2 clock average thickness,4 clock average thickness,6 clock average thickness,8 clock average thickness and 10 clock average thickness were measured by SPSS 15.0 software.Standard deviation (SD),coefficient of variation (CV) and interclass correlation coefficient (ICC) were calculated from the results of three-times tests by different examiner to evaluate the repeatability and from the results of two different examiners to assess the reproducibility.Written informed consent was obtained from each subject prior to any medical procedure.RESULTS: The average GCIPL thickness of OD was 85.12±3.95μm;the minimum average GCIPL thickness was 83.21±4.41μm;the standard deviation of OD in clock map was from 3.79μm to 4.84μm;CV(95%CI) was between 0.26 and 0.93;ICC was from 0.939 to 0.989.The average GCL+IPL thickness of OS was 84.65±8.73μm;the minimum average GCPL thickness was 81±13.08μm;the standard deviation of OS in clock map was from 8.24μm to 10.56μm;CV(95%CI) was between 0.92 and 4.94;ICC was from 0.264 to 0.968.CONCLUSION: Cirrus HD-OCT GCA software with automated algorithm can offer accurate and repeatable thickness profile of OCT retinal image.GCA is a useful and reliable approach to the measurement of intra-retinal layer thickness,which may improve the diagnosis and monitoring of retinal diseases.