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.

Optical coherence tomography analysis of axonal loss in band atrophy of the optic nerve.

AIMS: To measure axonal loss in patients with band atrophy of the optic nerve caused by optic chiasm compression using optical coherence tomography and to evaluate its ability in identifying this pattern of retinal nerve fibre layer (RNFL) loss. METHODS: Twenty eyes from 16 consecutive patients with band atrophy of the optic nerve and permanent temporal hemianopia due to chiasmal compression, and 20 eyes from an age and sex matched control group of 16 healthy individuals, were studied prospectively. All patients were submitted to an ophthalmic examination including perimetry and evaluation of the RNFL using optical coherence tomography. Mean RNFL thickness around the optic disc was compared between the two groups. RESULTS: The mean (SD) peripapillary RNFL thickness of eyes with band atrophy was 101.00 (9.89) microm, 62.21 (12.71) microm, 104.89 (12.60) microm, and 50.13 (16.88) microm in the superior, temporal, inferior, and nasal regions, respectively. The total RNFL mean was 79.94 (7.17) microm. In the control group, the corresponding values were 140.10 (16.06) microm, 86.50 (12.17) microm, 144.60 (15.70) microm, and 97.94 (16.02) microm. The total RNFL mean was 117.72 (9.53) microm. The measurements were significantly different between the two groups. Measurements in each of twelve 30 degrees divisions provided by the equipment also showed significantly different values between eyes with band atrophy and normal controls. CONCLUSIONS: Optical coherence tomography was able to identify axonal loss in all four quadrants as well as in each of the twelve 30 degrees segments of the disc. Thus, it seems to be a promising instrument in the diagnosis and follow up of neuro-ophthalmic conditions responsible for RNFL loss, even if predominantly in the nasal and temporal areas of the optic disc.