Abstract
Abstract: :
Purpose: To compare retinal nerve fiber layer (RNFL) measurements in patients with band atrophy of the optic nerve and in normal controls using an early commercial version of optical coherence tomography (OCT 1) with those of a recent version (OCT 3) of the same equipment Methods: Thirty four eyes (18 from 15 patients with band atrophy of the optic nerve and permanent temporal hemianopia due to chiasmal compression, and 16 from an age– and sex–matched control group of 13 healthy individuals) were submitted to evaluation of the RNFL using OCT 1 measurements. A second examination using OCT 3 was performed in the same eyes within a maximal interval of 2 months from the first examination. Mean RNFL thickness measurements around the optic disc, in each quadrant and in twelve 30–degrees segments were compared. Results: With OCT 1, the peripapillary RNFL thickness (mean ± SD) in eyes with band atrophy measured 101.93 ± 10.01 µm, 62.53 ± 12.11 µm, 104.21 ± 13.03 µm and 51.67 ± 16.93 µm in the superior, temporal, inferior and nasal regions, respectively. The total RNFL average was 80.45 ± 7.19 µm. With OCT 3 the corresponding values were 83.61 ± 12.19 µm, 42.05 ± 10.96 µm, 87.55 ± 13.19 µm and 45.16 ± 8.37 µm. The total RNFL average measured 64.61 ± 6.08 µm. Measurements from OCT 3 were significantly smaller (p < 0,001) than those of OCT1 except in the nasal quadrant (p = 0.17). Measurements in the 30–degree segments were smaller with OCT 3 (p < 0.05) except at clock hours 5, 4, 3 and 1. In normal eyes measurements with OCT 3 were also significantly smaller than those of OCT 1, except in the superior quadrant. Measurements in each of twelve 30–degrees divisions provided by the equipment also showed significantly smaller values with OCT 3 when compared with those of OCT 1, except at 12, 10, 9 and 7 o’clock meridians. Both OCT 1 and 3 RNFL measurements were significantly smaller (p < 0.0001) in eyes with band atrophy when compared with normal controls. Conclusions: RNFL measurements with OCT 3 were smaller than those with OCT 1 in almost all parameters evaluated but both versions of OCT were able to differentiate eyes with band atrophy from those of normal controls. Investigators and clinicians should be aware of this finding when comparing old RNFL measurement with those obtained with the new version of the equipment.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • clinical (human) or epidemiologic studies: systems/equipment/techniques • nerve fiber layer