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Comparative Anatomy and Physiology of the Mammalian Eye
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
The inner extension of the photoreceptor is the outer plexiform layer and is comprised of the axons of the photoreceptor cells, the dendrites of the bipolar cells, and Muller cells.4 The synapse between the photoreceptors and the bipolar cells differs between rods and cones. The cone synapse is termed a pedicle, while that of the rod is a spherule. Both contain synaptic vesicles which are believed to contain acetylcholine.4 By light microscopy, these synapses appear as a series of dashes in the innermost part of the outer plexiform layer and this region is often termed the middle limiting membrane.
Retinal Tears and Detachments
Published in Amy-lee Shirodkar, Gwyn Samuel Williams, Bushra Thajudeen, Practical Emergency Ophthalmology Handbook, 2019
Retinoschisis: This is derived from a microcystoid degeneration of the neurosensory retina with splitting at the level of the outer plexiform layer. Retinoschisis is more common in hyperopes and generally occurs inferiorly, temporally and commonly bilaterally. Myopic patients are much more likely to have retinal detachments than a retinoschisis. These can be differentiated through recognition that a retinoschisis causes an absolute scotoma whilst a detachment does not and that argon laser applied to the retina causes a visible burn in an area of retinoschisis but not with a detachment. There are also differences on examination though these are variable and should not be relied upon so will not be mentioned here.
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.
A comparative study between the possible protective role of melatonin versus its combination with adipose derived-mesenchymal stem cells on experimentally induced diabetic retinopathy in adult male albino rats (Histological and immunohistochemical study)
Published in Ultrastructural Pathology, 2023
Samar Reda, Ghada A Elsammak, Tamer G Elsayed, Samar Abdelaziz Mostafa
Examination of ultrathin sections in a control adult rat's retina showed a retinal pigment epithelial cell (RPE) with rounded euchromatic nucleus, resting on Bruch’s membrane. The cell had invaginations of the basal membrane, basal mitochondria, and apical microvilli. The outer segments of photoreceptor cells appeared with regularly arranged lamellar discs (Figure 6a). Outer nuclear layer formed of rods and cones cell bodies. Rod nuclei were characterized by heterochromatin condensation, and surrounded by a thin rim of cytoplasm. However, cone nuclei were less heterochromatic. The outer limiting membrane was observed as an electron dense line. (Figure 6b). Outer plexiform layer with ovoid transverse sections in the terminal synaptic process of the photoreceptors was observed. The nuclei of photoreceptors, muller cells, and bipolar cells were also seen (Figure 6c). Ganglion cell with oval euchromatic nucleus, multiple ribosomes, and mitochondria was noticed. Parts of inner plexiform layer containing mitochondria were seen (Figure 6d).
Bilateral Panuveitis Associated with Morvan Syndrome: A Case Report and Review of the Literature
Published in Ocular Immunology and Inflammation, 2023
Michael T. Kryshtalskyj, Robert G. Devenyi, Mili Roy
MoS falls within a broader new spectrum of diversely presenting autoimmune encephalitides termed “Caspr2 antibody associated disease.”1 MoS is the most anatomically generalized of these diseases, involving peripheral nerves and deep structures of the subcortical central nervous system (CNS) including the diencephalon, hippocampus, cerebellum, and brainstem.5 Caspr2 is a membrane protein expressed mostly on axonal juxtaparanodes and neuropil, a synaptically dense tissue consisting of unmyelinated axons, dendrites, and glial cell processes.5 The retina features two such layers: the inner plexiform layer (IPL) and the outer plexiform layer (OPL).11 The authors speculate whether this patient’s retinitis may have been caused by autoimmune reactivity to Caspr2 antigens within his retinal IPL and/or OPL as well as his CNS, reflecting the retina’s molecular and embryologic relatedness to neurons of the diencephalon.12
Atropine Affects the Outer Retina During Inhibiting Form Deprivation Myopia in Guinea Pigs
Published in Current Eye Research, 2022
Hong Liu, Donglong Chen, Zhikuan Yang, Xiaoning Li
Images were then analyzed through a semi-automated segmentation algorithm (Insight software, Phoenix Research Lab) to obtain the total retinal, outer retinal, and choroidal thickness. The retinal thickness was defined as the distance from the inner retinal boundary to the RPE layer. The outer retinal thickness was the length between the outer plexiform layer and the RPE layer. The inner retinal layer thickness was obtained by subtracting the retinal thickness from the outer retinal thickness. The choroidal thickness was measured from the RPE layer to the outer choroidal border. The borderlines were automatically recognized by Insight software program and then rectified manually if necessary, from which the raw data containing about 1000 evenly distributed points throughout each image were generated. The thickness was calculated by averaging the distance between borderlines at those points in raw data. As choroidal thickness varied with diurnal rhythm,16 all the images were taken between 15:00 and 17:00.