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Marta Pazos, Agnieszka Anna Dyrda, Alicia Gómez, Carlos Martín, Alfonso Anton-Lopez; Layer by Layer Automated Retinal Segmentationwith SD-OCT in the Macula of Normal and Glaucomatous Eyes. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4525.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate thickness of the different retinal layers in the macular area in normal and glaucomatous eyes using the automated layer by layer retinal segmentation software of SPECTRALIS Spectral-Domain Optical Coherence Tomograph (SD-OCT).
Sixty-four eyes (24 normal, 20 mild glaucoma and 20 moderate glaucoma) were prospectively studied. Complete ophthalmological examination was done, including reliable 24-2 Humphrey Visual Field (HFV), Intraocular Pressure (IOP), optic disc evaluation by glaucoma specialists and a good quality (Q≥20) SPECTRALIS posterior pole imaging with the automated retinal layers segmentation software (figure 1). Inclusion criteria for the normal group: IOP≤ 21 mmHg, normal optic disc appearance and normal HVF. For glaucoma: IOP>21 mmHg with glaucomatous optic disc. HVF Mean Deviation (MD) was used for glaucoma classification (mild: MD<-6Db; moderate: MD≥-6dB). A thickness map of 9 regions using the ETDRS circle (1-3-4 mm rings centered on the fovea) was obtained for each layer/group of layers including Retinal Nerve Fiber Layer (RNFL), Ganglion cell complex (GCCx) and Ganglion Cell layer (GCL). Differences among groups were assessed with ANOVA at p<0.01.
RNFL volume was 0.99±0.1 mm3 for the normal group, 0.84±0.1 mm3 for the mild, and 0.76±0.1 mm3 for the moderate glaucoma, and inferior quadrants showed the highest thickness difference (42±5, 32.4±8 and 24.9±4.6 µm, respectively)(p<0.001). GCCx volumes were 2.11±0.2, 1.74±0.2 and 1.54±0.2 mm3 for the normal, mild and moderate glaucoma, respectively (p<0.001). Both for GCCx and GCL, 8 regions in the mild glaucoma group (except the central area) and all 9 regions studied in the moderate glaucoma group, showed a significant thickness reduction when compared to normal eyes; when comparing mild vs moderate glaucoma, significant thinning was found in the inferior and temporal quadrants (see figure 2 for GCL quantitative results).
1. The Automated segmentation of the SD-OCT Spectralis allows visualization and quantification of the different retinal layers in the macula including isolated GCL (without Inner Plexiform Layer).<br /> 2. This segmentation showed significant thinning of RNFL, GCCx and GCL in glaucomatous eyes when compared to normal eyes.<br /> 3. GCCx and GCL thickness were found to be significantly thinner in the temporal and inferior areas of moderate glaucoma when compared to mild glaucoma.
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