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Comparative Anatomy and Physiology of the Mammalian Eye
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
The inner plexiform layer is formed by the axons of the bipolar and amacrine cells and the dendrites of the ganglion cells.4 The ganglion cells form a single layer over most of the retina, the exception being adjacent to the fovea in those species in which this is present. The axons of the ganglion cells are aggregated into nerve fiber bundles which make up the nerve fiber layer. These bundles travel parallel to the retinal surface through arcades formed by the foot processes of the Muller cells.4 These are nonmyelinated nerve fibers until they reach the optic nerve where they acquire myelination. Depending on the species and where the myelination begins, it may be evident clinically. The innermost layer of the retina is the internal limiting membrane. This is a thick basement membrane that is smooth on its internal surface, but conforms to the uneven Muller cell basal plasma membrane externally.4
Vitreoretinal surgery for idiopathic epiretinal membranes
Published in A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha, Vitreoretinal Surgical Techniques, 2019
H Richard McDonald, Robert N Johnson, Robert N Johnson, Everett Ai, J Michael Jumper, Arthur D Fu
These techniques enable the surgeon to remove the ERM in virtually all cases. During these dissections, it is inevitable that fragments of internal limiting membrane will be removed along with the ERM.80 It has been suggested that removal of internal limiting membrane may be associated with a decreased chance of visual improvement.46 Others have argued that the removal of portions of internal limiting membrane has little adverse effect on vision.48,50 Most surgeons make no special effort to avoid stripping membrane that may be inner limiting membrane. Despite the near certainty that ERM stripping will occasionally result in the removal of large areas of inner limiting membrane, the visual results of membrane removal are good.80
Impact of Retinal Stimulation on Neuromodulation
Published in Yu Chen, Babak Kateb, Neurophotonics and Brain Mapping, 2017
The ganglion cell layer and the axons from the ganglion cells, termed the nerve fiber layer, are next in the progression of retinal layers toward the inside of the eyeball. Loss of nerve fiber layer tissue is found to be an early biomarker for neurodegenerative diseases, such as Alzheimer’s disease and glaucoma (Valenti 2011). The final layer is the porous internal limiting membrane separating the retina from the vitreous. From there, 1.2 million signals travel through the optic nerve further into the brain for processing (Figure 22.12).
Clinical and Optical Coherence Tomography Analysis of Intraretinal Microcysts in Patients with Epiretinal Membrane
Published in Seminars in Ophthalmology, 2021
Mete Güler, Selma Urfalıoğlu, Elif Damar Güngör, Emine Atalay, Gökhan Köküsarı
Primary epiretinal membranes (ERM) are fibro cellular tissue proliferations that are seen in 1–3% of advanced age groups and are frequently located in the macular region.1 They may not be visually symptomatic in the early stages, but if they disrupt the retinal architecture, they may cause visual disturbances such as metamorphopsia, micropsia, and monocular diplopia.2 Pars plana vitrectomy (PPV) surgery can be successfully applied in the treatment of symptomatic ERMs. Epiretinal membranes can be peeled alone or together with the internal limiting membrane (ILM) in surgery.3 Diagnosis and follow-up of ERMs have become easier with the invention and use of high-resolution optical coherence tomography (OCT) devices.4 Intraretinal microcysts (IRM) can be detected with OCT before and/or after surgery in patients with ERMs. However, the clinical significance of these cysts has not been fully revealed.5 The aim of this study is to perform clinical and optical coherence tomography analysis of IRMs in patients who have undergone PPV for primary ERM treatment.
Vitreomacular disorders: a review of the classification, pathogenesis and treatment paradigms including new surgical techniques
Published in Clinical and Experimental Optometry, 2021
Mali Okada, Daniel Chiu, Jonathan Yeoh
In order to understand the pathogenesis of VMD, it is helpful to consider the normal anatomy and ageing process of the vitreous and its relationship to the VRI. The vitreous is a transparent gelatinous structure composed of a central vitreous body and an outer cortex.1 The vitreous is composed of Type II collagen arranged in parallel fibrils which is separated by water and hyaluronic acid.2 The vitreous cortex is firmly attached to the internal limiting membrane (ILM) of the retina at several points, most notably at the vitreous base, but also at the optic disc, fovea and along major retinal blood vessels.2 The ILM is a trilaminar structure with vitreous collagen cortex, extracellular matrix as an intermediate layer between the basal laminar formed by the Muller cell footplates. This firm adhesion at the vitreous base occurs as collagen fibrils penetrate the basal lamina to integrate with glial cells in this area. In contrast, at the rest of the VRI, collagen fibrils are adherent to the extracellular matrix on the basal lamina.
Analysis of Three-Dimensional Choroidal Volume with Enhanced Depth Imaging Findings in Patients with Recurrent Vogt-Koyanagi-Harada Disease
Published in Current Eye Research, 2021
Sukhum Silpa-Archa, Worapon Ittharat, Peranut Chotcomwongse, Janine M Preble, C. Stephen Foster
Choroidal segmentation was performed manually after disabling the automated retinal layer segmentation software. Reference lines of the built-in automated retinal segmentation were moved from the retinal boundaries to the choroidal boundaries. The internal limiting membrane line was moved to the outer part of the hyperreflective line corresponding to the base of the retinal pigment epithelium. The basement membrane line, serving as the reference line for the posterior edge of the retina, was moved to the posterior edge of the choroid, as demarcated by a hyperreflective margin line corresponding to the chorioscleral interface13 (Figure 1). The automated built-in calibration software was used to determine the distance between the two lines generating the choroidal thickness and volume map in a similar manner as for the retinal volume map. The standardized Early Treatment Diabetic Retinopathy Study grid was automatically placed in the macula by the Heidelberg SD-OCT software used for measuring macular thickness and volume mapping. The grid divides the macula into three rings with a diameter of 1 mm (fovea), 3 mm (inner ring), and 6 mm (outer ring). The grid further divides the inner and outer rings into four quadrants (superior, inferior, temporal, and nasal). The manually generated re-segmentation by the second grader was done in 31 horizontal B-scans in a macular volume scan.