The influence of eccentric scanning of optical coherence tomography on retinal nerve fiber layer analysis in normal subjects

Aim: To investigate the influence of eccentric scanning on retinal nerve fiber layer (RNFL) analysis using Stratus optical coherence tomography (OCT) in normal Koreans when the eccentricity of scanning occurs in 4 different directions. Methods: Thirty-one eyes of 31 persons underwent 1 concentric disk-centered and 4 superiorly, inferiorly, nasally and temporally eccentric RNFL OCT scans. Results: The average RNFL thickness measured by temporally eccentric scanning (115.1 μm) was significantly greater when compared with that found by concentric scanning (107.1 μm; p < 0.0001). The proportions of eyes outside normal limits on the RNFL analysis map using the criterion of ≥1 clock hour abnormal at the <1% level in superiorly (12/31, 38.7%), nasally (16/32, 51.6%) and temporally (12/31, 38.7%) eccentric scans were significantly different in comparison with the concentric (4/31, 12.9%) scan (p < 0.05). Conclusion: An off-centered OCT scan affected RNFL thickness measurement and its interpretation.