China
Africa
Explore chapters and articles related to this topic
Optical Coherence Tomography (Oct) and Fundus Fluorescein Angiography (FFA) in Neuro-Ophthalmology
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Ramandeep Singh, Deeksha Katoch, Mohit Dogra, Basavaraj Tigari, Simar Rajan Singh, Sahil Jain, Bruttendu Moharana, Sabia Handa, Mangat R. Dogra
In the acute phase of nonarteritic-anterior ischemic neuropathy (NA-AION), the pRNFL loss cannot be predicted. However, it is known in primate eyes that degree of initial pRNFL swelling correlated with the severity of atrophy as well as functional impairment as seen on electrophysiological responses.28 In early phase, mRGC thinning correlated more with visual field loss.29 Further, it has been shown that macular ganglion cell inner plexiform layer (GCIPL) thinning is significant in AION eyes as compared to unaffected eye.30
Low-grade Glioma Presenting in the Optic Pathways and Hypothalamus
Published in David A. Walker, Giorgio Perilongo, Roger E. Taylor, Ian F. Pollack, Brain and Spinal Tumors of Childhood, 2020
Peter M.K. de Blank, Ian Simmons, Astrid Sehested, Michael J. Fisher
OCT measures the thickness of the retinal nerve fiber layer (RNFL) and the ganglion cell layer-inner plexiform layer (GCL-IPL) using the back-scatter of infrared light (Figure 10.5). Retinal ganglion cell loss leads to thinning of these structures.64 RNFL thickness of less than 80 µm was associated with abnormal visual acuity or visual field deficit in 48 children and young adults with OPHG tumors.65 In addition, a 10% decline in RNFL in two or more retinal quadrants has been used to identify children with visual acuity or visual field loss with 70% sensitivity and 100% specificity in a longitudinal study of 46 children with OPHG (31 with NF1-OPHG).66 Decreased GCL-IPL measures may also discriminate normal from abnormal vision with improved accuracy.67
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.
Effect of hydroxychloroquine or chloroquine and short wavelength light on in vivo retinal function and structure in mouse eyes
Published in Clinical and Experimental Optometry, 2023
Wilson Heriot, Vickie HY Wong, Zheng He, Anh Hoang, Jeremiah KH Lim, Tomoharu Nishimura, Da Zhao, Andrew B Metha, Bang V Bui
Thickness measurements were taken on B-scans for all four annular sectors, with an inner and outer diameter of 600 and 1200 μm, respectively, centred around the optic nerve head (Figure 1A). All layers were extracted using the automated segmentation algorithm, after checking for segmentation errors in a masked fashion. Average thickness of the RPE (Figure 1B), photoreceptor outer segment (external limiting membrane to RPE), inner nuclear layer, ganglion cell complex (inner limiting membrane to inner plexiform layer), and total retina (inner limiting membrane to Bruch’s membrane) were quantified (Heyex, Heidelberg Engineering). The ‘photoreceptor outer segment’ here encompasses the outer segment as well as the ellipsoid zone of the inner segment. Each measurement was derived from the average of both eyes of each animal.
Deep learning: applications in retinal and optic nerve diseases
Published in Clinical and Experimental Optometry, 2023
Jason Charng, Khyber Alam, Gavin Swartz, Jason Kugelman, David Alonso-Caneiro, David A Mackey, Fred K Chen
The most fundamental DL application in glaucoma is to identify the disease from clinical data. Perhaps not surprisingly, the most common imaging modalities utilised in DL platforms were fundus photography and OCT, similar to clinician judgement. In the DL algorithms developed using fundus photography, it has been reported that the accuracy in glaucoma diagnosis was comparable, if not better, than human graders.90–92 In OCT-based DL platforms, various OCT data including macular cube scans,93 thickness maps of the retinal nerve fibre and ganglion cell-inner plexiform layers94,95 and peripapillary retinal nerve fibre layers,96 have been utilised to train individual algorithms. Interestingly, a recent study has reported a DL model trained with unsegmented peripapillary B-scans alone had a better accuracy in diagnosing glaucoma than conventional definition using global and sectorial RNFL thicknesses.97 The key advantage of such an approach is eliminating the need to manually segment OCT layers. Other imaging modalities that have been employed in DL algorithms for glaucoma diagnosis include red-free fundus photography,98 scanning laser ophthalmoscopy99 and OCT angiography.100
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