Comparison of retinal nerve fiber layer and central macular thickness measurements among five different optical coherence tomography instruments in patients with multiple sclerosis and optic neuritis

Background: To compare the mean central macular thickness (CMT) and the mean average optic nerve retinal nerve fiber layer (RNFL) thickness in the eyes of patients with a history of optic neuritis and/or multiple sclerosis (MS) using 5 commercially available optical coherence tomography (OCT) instruments. Methods: Cross-sectional study including 46 patients (92 eyes) with a history of optic neuritis and/or MS. Both eyes were imaged on the same day with 5 OCT instruments: 1 time-domain OCT (Stratus) and 4 different Fourier-domain (spectral-domain) OCT (3D OCT-1000, Cirrus, RTVue-100, and Spectralis). Results: Twenty-five patients (50 eyes) were included in the final analysis after excluding patients with diabetes, glaucoma, ocular hypertension, or retinal pathology and inadequate scan quality. Randomized block analysis of variance revealed statistically significant differences across instruments (P < 0.001) for both eyes for mean CMT and mean average optic nerve RNFL. When testing for significant differences in measurements from instrument to instrument, some difference was noted between the right and left eyes. Conclusions: Statistically significant differences exist among commercially available OCT instruments in measuring mean CMT and mean average RNFL thickness in patients with optic neuritis and/or MS. These findings likely result from the differences in data acquisition and segmentation algorithm software among OCT instruments. Awareness of these variations among OCT instruments will be important in using these instruments for clinical trials and management of patients with optic neuritis and/or MS.