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Ali S. Raza, Charles A. Reisman, Donald C. Hood; The Relationship between the Anatomy of the Fovea and Optic Disc and the Thickness of Retinal Layers Measured with Frequency Domain OCT. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2991.
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To better understand normal variation of inner retinal layers measured with frequency domain optical coherence tomography (fdOCT), the relationship between several anatomical factors and fdOCT layer thicknesses were examined.
One eye of 128 controls (data supplied by Topcon, Inc.) was tested with fdOCT (3D-OCT 2000, Topcon, Inc). To be included, subjects were required to have BCVA of 20/40 or better, a correction between +3.0 D and -6.0 D, IOP ≤ 21 mmHg, axial length between 22-26 mm, normal clinical exam, and normal SAP (SITA Standard, Zeiss, Inc.; PSD p > 0.05, normal GHT, reliability indices all ≤ 33%). Exclusion criteria included history of ocular disease or a family history of glaucoma. Two 10° "cube" fdOCT scans of the macula and the optic disc (128 B-scans x 512 A-scans) were acquired. A previously validated computer algorithm  segmented the images by marking the following borders: vitreous/inner limiting membrane (ILM), retinal nerve fiber layer (RNFL)/retinal ganglion cell (RGC), inner plexiform layer (IPL)/inner nuclear layer (INL), INL/outer plexiform layer (OPL), and Bruch’s membrane (BM)/choroid. The layers measured were: RNFL (ILM to RNFL/RGC), RGC+IPL (RNFL/RGC to RGC/IPL), and the total receptor (TR; the INL/OPL to BM/choroid). Scans with acquisition or algorithm artifacts were rejected. The centers of the macula and disc scans were marked based on both C-face and B-scan images and these cube scans were then coregistered. Pearson coefficients (R) were calculated.
The fovea-to-disc angle did not correlate well with the locations of the circumpapillary (cp) RNFL peaks (RSUP=0.09, RINF=0.12) or blood vessels (BVs; RSUP=0.13, RINF=0.14). As suggested, BVs moderately correlated with cpRNFL peak locations (RSUP=0.51, RINF=0.27). The disc radius or the fovea-to-disc distance did not correlate well with the cpRNFL thickness (R=0.02, R=0.18) or the eccentricity of the peak of the macular RGC+IPL thickness (R=0.13, R=0.12). The macular RGC+IPL peak height moderately correlated with the mean cpRNFL thickness (R=0.37), while the mean macular TR thickness did not correlate well with the mean cpRNFL thickness (R=0.20).
Blood vessel locations may have potential in reducing variability. The potential of other anatomical factors in this study seems limited. 1. Yang Q, et al., Opt. Exp. 2010; 2. Hood DC, et al. J. Glaucoma 2010.
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