The Effect of Software Upgrade on Optical Coherence Tomography Measurement of the Retinal Nerve Fiber Layer Thickness

PURPOSE: To determine the effect of software upgrades on retinal nerve fiber layer (RNFL) thickness measurements taken by spectral domain optical coherence tomography (SD-OCT). METHODS: Eighty normal eyes (40 patients) were scanned for RNFL thickness measurements using Spectralis (Heidelberg Engineering, Heidelberg, Germany) SD-OCT. Scan analysis was performed using version 4.0 software and then reanalyzed with version 5.1.3. Student paired t testing and Pearson's correlation coefficient were used for statistical analysis. RESULTS: Average and quadrant RNFL thicknesses generated using version 4.0 and 5.1.3 software on Spectralis demonstrated high correlation (r = 0.955-0.998). Average RNFL thickness using version 4.0 was 0.08μm thinner than version 5.1.3 (p = 0.409). Quadrant RNFL differences ranged from -0.26 to +0.97μm (p = 0.146-0.915). Segmentation errors were reduced 33% after the upgrade. CONCLUSION: Minor RNFL thickness changes may occur after software upgrades in Spectralis OCT. The differences did not reach statistical significance but segmentation errors were improved.