Repeatability of Peripapillary Retinal Nerve Fiber Layer and Inner Retinal Thickness Among Two Spectral Domain Optical Coherence Tomography Devices

PURPOSE. To compare measurement of macular inner retina and peripapillary retinal nerve fiber layer (pRNFL) thickness using two spectral-domain optical coherence tomography (SD-OCT) devices in glaucoma patients, patients with ocular hypertension, idiopathic and atypical Parkinson disease, and healthy controls. METHODS. A total of 171 eyes of 146 participants underwent successful pRNFL and macular scanning and automated measurement of ganglion cell layer + inner plexiform layer (GCL-IPL) using Cirrus HD-OCT or retinal nerve fiber layer + GCL-IPL (RNFL-GCL-IPL) using RTVue-100. Macular RNFL was added to the GCL-IPL thickness measured by Cirrus and was compared to the RNFL-GCL-IPL thickness of the RTVue in the corresponding Cirrus sectors. Intraclass correlation coefficient (ICC) was calculated to determine repeatability of three consecutive measurements; ICC and Bland-Altman analysis to assess agreement between OCTs; Pearson's correlation coefficient to assess strength of linear correlation. RESULTS. Repeatability of average macular RNFL-GCL-IPL thickness measurement was excellent with an ICC of 0.998 for Cirrus and 0.995 for RTVue. Repeatability was also good for average pRNFL thickness measurements. Both instruments demonstrated a good consistency in measurements with ICC values ranging from 0.844 to 0.862 for macular RNFL-GCL-IPL and 0.718 to 0.958 for pRNFL thickness. CONCLUSIONS. Measurement of pRNFL and macular RNFL-GCL-IPL thickness has a high degree of repeatability for both OCT devices. Despite a high correlation between measurements of the two OCT devices and fair to excellent ICC values representing a high consistency in the measurements of the two devices, RTVue measured a thicker macular RNFL-GCL-IPL and pRNFL thickness.