Interest of analysis of circumpapillary retinal nerve fibers layer thickness at different measurement diameters

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PurposeThe analysis of the circumpapillary retinal nerve fiber layer (RNFL) is a major data in structural analysis in glaucoma. Since OCT development, analysis is on a circle of 3.4 mm diameter. This study evaluates the diagnostic capability of an RNFL analysis with different diameter measurements.Methods60 glaucomatous and 58 control patients had a complete ophthalmological exam to exclude patients with papillary morphological abnormalities (coloboma, dysversion …). Others had an OCT Spectralis (Heidelberg Engineering, Germany) of RNFL on 4 circles of different diameters: 3.4, 3.5, 4.1 and 4.7 mm. Only one eye per patient was randomly included. The diagnostic capabability of each of these circles was analyzed for global mean thickness and for each sector (temporal, temporal‐superior, nasal‐superior, nasal, nasal‐inferior and temporal‐inferior) by calculating areas under ROC curve (AUROC).ResultsPatients were comparable for clinical characteristics. In glaucomatous patient group, 58.9% of the patients were early glaucoma (MD> ‐6 dB) and 21.4% of the patients were severe (MD <‐12 dB). For conventional RNFL measurement (3.4 mm), the temporal‐inferior sector had the highest diagnostic capability with an AUROC of 0.916. For the 3.5 mm measurement, the global mean thickness of the RNFL had the highest diagnostic capability (AUROC = 0.909). For the 4.1 mm measurement, the global mean thickness of the RNFL had the highest diagnostic capability (AUROC = 0.915). For the 4.7 mm measurement, the average thickness of the temporal‐inferior sector had the highest diagnostic capability (AUROC = 0.909). There was no statistically significant difference between these 4 AUROC.ConclusionsRegardless of the diameter of RNFL analysis, the diagnostic capability remains very good with no significant difference in patients with normal papillary morphology.