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Jinfeng Qu, Muneeswar Nittala, Amirhossein Hariri, David Wu, Srinivas Sadda; Classification and Quantitative Analysis of Geographic Atrophy Lesions Using Spectral-Domain Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5856.
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The junctional zone at the border of areas of geographic atrophy (GA) in eyes with age-related macular degeneration (AMD) is an important target region for future therapeutic strategies. The goal of this study was to perform a detailed classification and quantitative characterization of the junctional zone using Spectral-Domain Optical Coherence Tomography (SD-OCT).
SD-OCT volume cube scans (Spectralis OCT, 1024 x 37, ART=9) were obtained from 11 eyes of 8 patients with GA due to AMD. Volume OCT data were imported into previously-described validated grading software (3D-OCTOR) and manual segmentation of the retinal pigment epithelium (RPE) and photoreceptor layers was performed on all B-scans (total of 407). RPE and photoreceptor defect maps were produced for each case. In addition, all B-scans which included the atrophic lesion were individually scrutinized to classify the overlap configuration of the border zone into one of three categories (Type 0; exact correspondence between the edge of the RPE defect and photoreceptor defect; Type 1: loss of photoreceptors proximal to the edge of the RPE defect; Type 2: preservation of photoreceptors beyond the edge of the RPE defect). The relative proportion of the various border configurations was expressed as a percentage of the perimeter of RPE defect.
183 of the B-scans were found to pass through the GA lesion, yielding 366 individual GA borders which were separately analyzed and classified. Quantitative manual segmentation analysis demonstrated that the mean area of the RPE defect was 4.2±4.9 mm2, which was significantly smaller than the mean area of the photoreceptor defect which measured 4.8±4.6 mm2 (paired t-test: p=0.005).When analyzed as a percentage of the perimeter of the atrophic lesion, the Type 1 configuration (photoreceptor loss despite RPE preservation) was more prevalent (45.6-96.8%, mean 66.0±14.2%) than either the Type 2 (0.9-35.5%, mean 17.0±11.2%) or Type 0 (2.3-32.7%, mean 19.3±10.8%) configurations.
The size of the OCT-visible RPE and photoreceptor defect in GA lesions differ significantly.There were significant areas where the photoreceptors survived despite absence of visible RPE cells, and also areas of photoreceptor loss despite apparent RPE preservation. These findings have implications for development of therapeutic strategies, particularly cell-replacement approaches.
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