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D. P. Castro, L. C. Castro, C. Krishnan, C. Mattox; Variability of the Optical Coherence Tomography Measurement of the Peripapillary Retinal Nerve Fiber Layer According to Optic Disc Margin Distance. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2255.
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© ARVO (1962-2015); The Authors (2016-present)
To verify the variability of peripapillary retinal nerve fiber layer (RNFL) thickness in glaucomatous and glaucoma suspect patients on Fourier domain optical coherence tomography (OCT) according to the optic disc margin distance.
Prospective cross sectional study in which 3D optic disc OCT scans (3D1000 Topcon OCT) were performed twice in one eye of 27 glaucoma or glaucoma suspect patients. After the measurement of the optic disc size with Heidelberg Retinal Tomography III, three different circle scans centered on optic disc with radius 0.4; 0.7; 1.0mm larger than the optic disc radius were recorded from the 3D OCT scan. RNFL thickness was computed for six subfields. All scans were manually corrected for software breaks of the 2 boundaries of the RNFL. Inter-scan reproducibility of each circle was assessed with intraclass correlation coefficients (ICCs).
12 eyes from glaucoma suspects and 15 eyes from glaucoma patients (11 POAG; 4 secondary glaucoma) were scanned. The mean [standard deviation (SD)] vertical and horizontal optic disc size were respectively 1.7 (0.2)mm, and 1.5 (0.2)mm. The average (SD) RNFL thickness progressively decreased with the increasing distance to the optic disc border (0.4; 0.7; 1.0mm) on both first [103.6 (20.8); 94.5 (16.1); 80 (13.9)µm] and second scans [102.9 (22.7); 93.9 (17.4); 79.9 (15.8)µm] (p<0.0001). ICCs (95% confidence interval) showed good reproducibility on every sub-field in all the three size circles. Superior temporal sub-field was the most reliable on both 0.4 and 0.7mm size circles [0.96 (0.92-0.98)] but was the less reliable [0.74 (0.52-0.87)] in the 1.0mm size circle. The less reliable subfield in the 0.4 and 0.7mm size circle was inferior nasal [0.66 (0.38-0.83)] and superior nasal [0.79 (0.59-0.90)], respectively. The ICC of the average RNFL thickness in the 0.7mm size circle [0.96 (0.92-0.98)] was similar to the 1.0mm size circle [0.96 (0.91-0.98)], and both were greater than the 0.4mm [0.90 (0.89-0.98)].
The peripapillary RNFL thickness varies according to the optic disc distance, progressively thinning with the increase of the distance from the optic disc margin. Reproducibility between 2 scans is good for all the three circles size and there is no significant difference among them.
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