To assess the agreement and compare the performance of glaucoma diagnosis of peripapillary retinal nerve fiber layer (RNFL) thickness measurements between two different spectral-domain optical coherence tomography (SD-OCT) devices.

Eighty nine eyes of 56 patients with glaucoma and 42 eyes of 25 healthy individuals were imaged with Cirrus and Spectralis OCT in a single visit. Agreement between RNFL thickness measurements was assessed using intraclass coefficient (ICC) and Bland-Altman plots. The discriminating abilities of the two techniques for detection of glaucoma were compared by the area under the receiver operating characteristic curves (AUC) for quadrants and average RNFL thickness.

ICC values for agreement between both instruments were good for quadrants and average RNFL thickness (all ≥ 0.81). However, Spectralis OCT measurements were significantly greater than Cirrus OCT for temporal quadrant (difference = 4.27 µm in normal group, 3.91 µm in glaucoma group, p < 0.001 for both). The RNFL thickness parameter with the largest AUCs was the average RNFL thickness for the Spectralis OCT and the Cirrus OCT (0.85 vs. 0.87, p = 0.30). The pair-wise comparison among the receiver operating characteristic curves showed no statistical difference for all parameters.

Although Spectralis OCT measurements were significantly greater than Cirrus OCT for temporal quadrant, agreement of RNFL measurement between both the devices was generally good and there was no statistically significant difference in the performance of glaucoma diagnosis between both instruments.