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Nicolas Cuenca, Isabel Ortuño Lizarán, Isabel Pinilla; Cellular Characterization of the OCT Retinal Bands Using Specific Immunohistochemistry Markers.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1319.
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© ARVO (1962-2015); The Authors (2016-present)
Optical coherence tomography (OCT) has been a technological breakthrough in the diagnosis, treatment and follow-up of many ocular diseases, especially retinal and neuro-ophthalmological pathologies. Until now, several controversies have arisen about the specific cell types that represent the bands observed in the OCT especially over the four outer retinal bands. The aim of this study was to correlate the four-hypereflective bands observed in the OCT with the histological structures using human retinal sections and immunocytochemistry at the fovea level.
Vertical cryosections of human retinas were immunostained with antibodies specific for cones photoreceptors, bipolar cells, Müller and RPE cells and mitochondria markers, and visualized using confocal microscopy. Triple immmunolabeling allowed distinguishing between cells types and different cell compartments.
Immunostaining with GNB3 and CRALBP showed all retinal layer at the foveola, especially the separation between the outer nuclear layer and the Henle fiber layer. CRALBP and cytochrome C immunolabeling revealed that the hypereflective bands 1 and 2, observed in the OCT, correspond to the outer limiting membrane and the ellipsoids respectively, separated by the cone myoids. CRALBP, cytochrome C and GNB3 showed that the RPE interdigitations extend along the entire external segment of the cones, allowing us to discard that the third band may correspond to the interdigitation zone. However, the colocalization of small fragments of cone outer segments within of RPE let us to characterize the third band as the cone phagosomes band located in the top of the RPE. Finally, we propose that the fourth band correspond to the accumulation of mitochondria at the basal portion of the RPE identified by cytochrome C immunoreactivity and that the hyporeflective band between band 3 and 4 correspond to the RPE melanosomes.
Our immunohistochemical results confirm the previously described bands using OCT technology except for the four outer bands at the foveola. We provide demonstration that the bands 1 and 2 correspond to the outer limiting membrane and the ellipsoids respectively. The band 3 corresponds to the cone phagosomes zone located into the apical portion of the RPE. The fourth band may be the reflection of the basal mitochondria of the RPE and the hyporeflective band between 3 and 4 correspond to the melanosomes.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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