Comparison of retinal nerve fibre layer measurements using optical coherence tomography versions 1 and 3 in eyes with band atrophy of the optic nerve and normal controls

AIMS: To compare retinal nerve fibre layer (RNFL) measurements were carried out with two different versions of an optical coherence tomography device in patients with band atrophy (BA) of the optic nerve and in normal controls. METHODS: The RNFL of 36 eyes (18 with BA and 18 normals) was measured using an earlier version of an optical coherence tomography device (OCT-1). The measurements were repeated using a later version of the same equipment (OCT-3), and the two sets of measurements were compared. RESULTS: Using OCT-1, the peripapillary RNFL thickness (mean+/-SD, in microm) in eyes with BA measured 80.42+/-6.94, 99.81+/-14.00, 61.69+/-13.02, 101.70+/-12.54, and 57.36+/-16.52 corresponding to the total RNFL average, superior, temporal, inferior, and nasal quadrants, respectively. Using OCT-3, the corresponding measurements were 63.11+/-6.76, 81.22+/-13.34, 39.50+/-8.27, 86.72+/-15.16, and 45.05+/-8.03. Each of these measurements was significantly smaller with OCT-3 than with OCT-1. In normal eyes, RNFL average and temporal quadrant OCT-3 values were significantly smaller than OCT-1 values, but there was no significant difference in measurements from the superior, inferior, and nasal quadrant. CONCLUSIONS: RNFL measurements were smaller with OCT-3 than with OCT-1 for almost all parameters in eyes with BA and in the global average and temporal quadrant measurements in normal eyes. Investigators should be aware of this fact when comparing old RNFL measurement with values obtained with later versions of the equipment.