Mitsch C, et al. - In this study, for the first time, neuroretinal rim width (NRW) measurements acquired with the Carl Zeiss Meditech Cirrus HD-OCT 5000 and the Heidelberg Engineering Spectralis spectral domain optical coherence tomography (SD-OCT) are systematically compared. Examining 20 eyes of each 20 glaucoma patients and 20 age-matched healthy, they noted markedly higher cirrus mean NRW than Spectralis mean NRW for healthy subjects, on average by 91 μm. With higher mean NRW values, an increase in the difference between devices was observed and this increase was especially pronounced for the nasal quadrant (158 μm). On the contrary, NRW was comparable between Cirrus and Spectralis OCT for glaucoma patients. Based on these findings, researchers recommend practicing caution while comparing Spectralis and Cirrus NRW measurements only in patients with morphologically manifest glaucoma. The continuous usage of the same device is recommended for morphological progression analysis.