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Layers of retina3/19/2023 ![]() ![]() Since the macula contains a large number of retinal ganglion cells, its importance in glaucoma assessment is emerging towards becoming a standard component of glaucoma evaluation. Retinal nerve fiber layer thickness is most commonly measured using Spectral-Domain Optical Coherence Tomography (SD-OCT) with commercially available units such as the Cirrus (Carl Zeiss Meditec, Inc., Dublin, CA, USA) and Spectralis (Heidelberg Engineering, Inc., Franklin, MA, USA) OCT. Giangiacomo MD, Yao Liu MD, MS, in Ocular Telehealth, 2023 Retinal nerve fiber layer and ganglion cell complex assessment with OCT The RNFL thickness profile normally presents a ‘double hump’ pattern corresponding to the superior and inferior quadrants, where the RNFL is thicker.Īnnette L. One of the most useful RNFL displays in clinical practice is the sinusoidal profile wave corresponding to the RNFL thickness profile 360 degrees around the optic nerve, starting from the temporal region and proceeding through the superior, nasal, inferior, and back to the temporal region (TSNIT). The RNFL thickness may be displayed as an average for the overall map, quadrants, sectors, hemispheres, and/or clock hours. Results from the two eyes are also compared and any discrepancy between the two is highlighted. ![]() The results are displayed in various forms including a false color scale where green represents normal, yellow represents a borderline RNFL thickness (less than 5% and greater than 1% probability of being normal), and red represents an abnormal RNFL thickness (less than 1% probability of being normal). RNFL thickness is then compared with age, ethnicity, and disc size-matched normative databases. One of the reasons that measurement of the RNFL between machines is not comparable is that different machines use circles of different diameters. Most machines calculate the RNFL thickness along a circle of a predefined diameter (usually between 3.4 and 3.5 mm) centered on the optic disc ( Fig. The RNFL thickness is calculated as the distance between the internal limiting membrane and the outer boundary of the RNFL ( Fig. In Handbook of Retinal OCT: Optical Coherence Tomography (Second Edition), 2022 Retinal Nerve Fiber Layer Thickness The inferior and superior quadrant RNFL thickness has been demonstrated to be the most useful in glaucoma diagnosis. This normally presents a ‘double hump’ pattern corresponding to the superior and inferior quadrants, where the RNFL is thickest. One of the most useful RNFL displays in clinical practice is the sinusoidal signal profile wave corresponding to the RNFL thickness profile 360° around the optic nerve, starting from the temporal region and proceeding through the superior, inferior, nasal and back to the temporal region (TSINT). The RNFL thickness may be displayed as an average for the overall map, for quadrants, sectors, hemispheres or clock hours. The results are displayed in various forms including a false color scale where green represents normal, yellow represents a ‘borderline’ RNFL thickness (less than a 5% probability of being normal), and red represents an abnormal RNFL thickness with less than a 1% probability of being normal. RNFL thickness is then compared to age, ethnicity and disk size-matched normative databases. One of the reasons that measurement of the RNFL between machines is not comparable is that different machines use circles of different diameters around the center of the optic nerve head. Because the RNFL varies with distance from the center of the optic nerve, most machines use a circle of a pre-defined diameter (usually between 3.4–3.46 mm) around the center of the optic nerve as the reference point at which to calculate RNFL thickness. RNFL thickness is calculated by the OCT devices as the distance between the internal limiting membrane and the outer aspect of the NFL ( Fig. In Handbook of Retinal OTC, 2014 Retinal Nerve Fiber Layer (RNFL) Thickness ![]()
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