Agreement of Two Different Spectral Domain Optical Coherence Tomography Instruments for Retinal Nerve Fiber Layer Measurements

Purpose: to determine the agreement between spectralis and cirrus spectral domain optical coherence tomography (sd-oct) measurements of peripapillary retinal nerve fiber layer (rnfl) thickness. methods: suspected or confirmed cases of glaucoma who met the inclusion criteria underwent peripapillary rnfl thickness measurement using both the spectralis and cirrus on the same day within a few minutes. results: measurements were performed on 103 eyes of 103 patients with mean age of 50.4±17.7 years. mean rnfl thickness was 89.22±15.87 versus 84.54±13.68 μm using spectralis and cirrus, respectively. the difference between measurements and the average of paired measurements with the two devices showed a significant linear relationship. bland-altman plots demonstrated that spectralis thickness values were systematically larger than that of cirrus. conclusion: spectralis oct generates higher peripapillary rnfl thickness readings as compared to cirrus oct; this should be kept in mind when values obtained with different instruments are compared during follow-up.