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Level Set Methods in Segmentation of SDOCT Retinal Images
Published in Ayman El-Baz, Jasjit S. Suri, Level Set Method in Medical Imaging Segmentation, 2019
N Padmasini, R Umamaheswari, Yacin Sikkandar Mohamed, Manavi D Sindal
As shown in Figure 5.2, the retina is a ten layered structure, viz., Nerve fiber layer (NFL), Ganglion cell layer (GCL), Inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), External limiting membrane (ELM), Ellipsoid zone (previously referred to as the IS/OS junction), Interdigitation zone, and Retinal pigment epithelium (RPE). Automatic detection of diabetic maculopathy from SDOCT retinal images is extremely important in analyzing the stage of diabetic retinopathy. Diabetic maculopathy is the condition of fluid being accumulated in between the retinal layers. As shown in Figure 5.3, SDOCT images provide more details about the intraretinal fluid and subretinal fluid present in the macula scan images.
Multiphoton imaging of the retina
Published in Pablo Artal, Handbook of Visual Optics, 2017
Robin Sharma, Jennifer J. Hunter
Within the inner plexiform layer, there is a pattern of weak fluorescence that is thought to correspond to the synaptic connections between ganglion cell dendrites, bipolar cells, and amacrine cells (Figure 9.4c). In the outer plexiform layer, there is a pattern of large and small fluorescent disks that likely correspond to cone pedicles and rod spherules (Figure 9.4e). It is in this layer that they connect with bipolar and horizontal cells. In primate retina, streaks of fluorescence radiating from the fovea center are visible between the outer plexiform layer and the outer nuclear layer (Figure 9.4f). These are possibly the Henle fibers.
The Biological Bases of Photoreception in the Process of Image Vision
Published in Agnieszka Wolska, Dariusz Sawicki, Małgorzata Tafil-Klawe, Visual and Non-Visual Effects of Light, 2020
Agnieszka Wolska, Dariusz Sawicki, Małgorzata Tafil-Klawe
Amacrine cells are interneurons, involved in the analysis of visual signals before they leave the retina, mediating the lateral interconnections. They are lateral inhibitory interneurons which produce effects at the level of bipolar cell output synapses (reciprocal synapses onto bipolar cell synaptic terminals). Glycinergic amacrine cells are the narrow-field type (AII amacrine cells), and GABA-ergic amacrine cells are the wide-field type [Tsukamoto et al. 2017]. Both dendrites and the axon-like-processes of dopaminergic amacrine cells narrowly stratify close to the outer border of the inner plexiform layer, forming the “off” switch for the AII-mediated rod pathway. Morphological and physiological studies make it possible to identify about 30 types of amacrine cells. One of these is part of the pathway for rod vision (AII) briefly described above: from rod to bipolar cells to amacrine cells to ganglion cells. Another type responds strongly at the onset of a continuing visual signal, while still another one at the offset of a visual signal. Both responses fade quickly. Other amacrine cells, which are directionally sensitive, respond to the movement of a spot across the retina in a specific direction. A strong correlation was found between the number of amacrine cell synaptic contacts and the number of bipolar cell axonal ribbons. Formation of bipolar cell output at each ribbon synapse may be effectively regulated by a few nearby inhibitory inputs of amacrine cells. All the amacrine cells are connected to five of the six OFF bipolar cell types via chemical synapses and seven of the eight ON cone bipolar cell types via electrical synapses (gap junctions).[Tsukamoto et al. 2017]
Multi-scale filters implemented by cellular automaton for retinal layers modelling
Published in International Journal of Parallel, Emergent and Distributed Systems, 2020
In the mammalian retina, photoreceptor cells are essentially connected with the horizontal and bipolar cells forming the OPL layer. The Inner Plexiform Layer (called IPL) is composed of amacrine and ganglion cells. They have their axons as outputs forming the optic nerve. The retina has two types of cells: horizontal and amacrine cells for regularisation and bipolar and ganglion cells for differentiation.