Afferent Visual Pathway Amr Hassan, M.D.,FEBN Associate Professor of Neurology Cairo University 2017
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Guess Who? Answer
Guess Who? Answer soon became interested in ophthalmology and was appointed Hansen Grut's assistant in 1879. Bjerrum's scientific concern was the relationship between visual perception of form and the resolving power in localized areas of the retina. He demonstrated this in his thesis entitled ' UndersØgeleser over Formsans og Lyssands i forskellige Øjensyngdomme (Investigations on the form sense and light sense in various eye diseases). This title is deliberately given in Danish to indicate that through his entire lifetime it was mandatory for him to write his publications in Danish. An antipathy against German, in those days the language of science, may have been gained in a childhood so filled with tension regarding nationalism. The scientific achievement that made the name Bjerrum universally known was conceived during his work on the relationship between visual acuity and the perception of the bright stimuli in various retinal zones. In accordance with his own modest attitude, this discovery was published in 1889 in a small paper which in translation was called 'An addendum to the usual examination of the visual field of glaucoma'. At that time Bjerrum was studying the visual field by means of small white objects. The idea Jannik Peterson Bjerrum of this investigation was to record the performance of every single functional unit of the retina. As a Danish ophthalmologist. Born 1851, died 1920 minimum such units in Bjerrum's opinion would subtend a visual angle of one minute of arc (in the Jannik Petersen Bjerrum was born 26th December 1851 macular region). However, even a small test object in Skarbak, a village in the most southern part of would subtend a visual angle exceeding two degrees Jutland in the border district between the Danish and accordingly cover a multitude of functional units. -
Neuroanatomy Crash Course
Neuroanatomy Crash Course Jens Vikse ∙ Bendik Myhre ∙ Danielle Mellis Nilsson ∙ Karoline Hanevik Illustrated by: Peder Olai Skjeflo Holman Second edition October 2015 The autonomic nervous system ● Division of the autonomic nervous system …………....……………………………..………….…………... 2 ● Effects of parasympathetic and sympathetic stimulation…………………………...……...……………….. 2 ● Parasympathetic ganglia ……………………………………………………………...…………....………….. 4 Cranial nerves ● Cranial nerve reflexes ………………………………………………………………….…………..…………... 7 ● Olfactory nerve (CN I) ………………………………………………………………….…………..…………... 7 ● Optic nerve (CN II) ……………………………………………………………………..…………...………….. 7 ● Pupillary light reflex …………………………………………………………………….…………...………….. 7 ● Visual field defects ……………………………………………...................................…………..………….. 8 ● Eye dynamics …………………………………………………………………………...…………...………….. 8 ● Oculomotor nerve (CN III) ……………………………………………………………...…………..………….. 9 ● Trochlear nerve (CN IV) ………………………………………………………………..…………..………….. 9 ● Trigeminal nerve (CN V) ……………………………………………………................…………..………….. 9 ● Abducens nerve (CN VI) ………………………………………………………………..…………..………….. 9 ● Facial nerve (CN VII) …………………………………………………………………...…………..………….. 10 ● Vestibulocochlear nerve (CN VIII) …………………………………………………….…………...…………. 10 ● Glossopharyngeal nerve (CN IX) …………………………………………….……….…………...………….. 10 ● Vagus nerve (CN X) …………………………………………………………..………..…………...………….. 10 ● Accessory nerve (CN XI) ……………………………………………………...………..…………..………….. 11 ● Hypoglossal nerve (CN XII) …………………………………………………..………..…………...…………. -
Structural Brain Abnormalities in Patients with Primary Open-Angle Glaucoma: a Study with 3T MR Imaging
Glaucoma Structural Brain Abnormalities in Patients with Primary Open-Angle Glaucoma: A Study with 3T MR Imaging Wei W. Chen,1–3 Ningli Wang,1,3 Suping Cai,3,4 Zhijia Fang,5 Man Yu,2 Qizhu Wu,5 Li Tang,2 Bo Guo,2 Yuliang Feng,2 Jost B. Jonas,6 Xiaoming Chen,2 Xuyang Liu,3,4 and Qiyong Gong5 PURPOSE. We examined changes of the central nervous system CONCLUSIONS. In patients with POAG, three-dimensional MRI in patients with advanced primary open-angle glaucoma revealed widespread abnormalities in the central nervous (POAG). system beyond the visual cortex. (Invest Ophthalmol Vis Sci. 2013;54:545–554) DOI:10.1167/iovs.12-9893 METHODS. The clinical observational study included 15 patients with bilateral advanced POAG and 15 healthy normal control subjects, matched for age and sex with the study group. Retinal rimary open angle glaucoma (POAG) has been defined nerve fiber layer (RNFL) thickness was measured by optical formerly by intraocular morphologic changes, such as coherence tomography (OCT). Using a 3-dimensional magne- P progressive retinal ganglion cell loss and defects in the retinal tization-prepared rapid gradient-echo sequence (3D–MP-RAGE) nerve fiber layer (RNFL), and by corresponding psychophysical of magnetic resonance imaging (MRI) and optimized voxel- abnormalities, such as visual field loss.1 Recent studies by based morphometry (VBM), we measured the cross-sectional various researchers, however, have suggested that the entire area of the optic nerve and optic chiasm, and the gray matter visual pathway may be involved in glaucoma.2–23 Findings from volume of the brain. -
Twelfth International Visual Field Symposium
PERIMETRY UPDATE 1996/1997 PERIMETRY UPDATE 199611997 Proceedings of the Xllth International Perimetric Society Meeting Wijrzburg, Germany, June 4-8, 1996 edited by Michael Wall and Anders Heijl KUGLER PUBLICATIONS Amsterdam / New York ISBN 90-6299-139-4 Distributors For the LJ S A and Canada: DEMOS 386 Park Avenue South, Suite 201 New York, NY 10016 Telefax (+212) 683-0072 For all other countries Kugler Publications P.O. Box 11188 1001 GD Amsterdam, The Netherlands 0 Copyright 1997 Kugler Publications All rights reserved No part of this book may be translated or reproduced in any form by print, photoprint, microfilm, or any other means without prior written permission of the publisher. Table of Contents v TABLE OF CONTENTS Preface xi New methods of perimetry Contrast sensitivity perimetry in experimental glaucoma: investigations with degenerate gratings R.S. Harwerth and E.L. Smith, III 3 The role of spatial and temporal factors in frequency-doubling perimetry C.A. Johnson and S. Demirel 13 Motion detection perimetry: properties and results M. Wall, C.F. Brito and K. Kutzko 21 Stimulus orientation can affect motion sensitivity in glaucoma M.C. Westcott, F.W. Fitzke and R.A. Hitchings 35 Short-wavelength automated perimetry and motion automated perimetry in glaucoma P.A. Sample, Ch.F. Bosworth, I. Irak and R.N. Weinreb 43 Blue-on-yellow perimetry in patients with ocular hypertension H. Maeda, Y. Tanaka and T. Sugiura 45 Mass screening for visual field defects with snowfield campimetry: results of a field study using local TV broadcasting A.C. Gisolf, J. Kirsch, H.K. -
Asymmetries of Dark and Bright Negative Afterimages Are Paralleled by Subcortical on and OFF Poststimulus Responses
1984 • The Journal of Neuroscience, February 22, 2017 • 37(8):1984–1996 Systems/Circuits Asymmetries of Dark and Bright Negative Afterimages Are Paralleled by Subcortical ON and OFF Poststimulus Responses X Hui Li,1,2 X Xu Liu,1,2 X Ian M. Andolina,1 Xiaohong Li,1 Yiliang Lu,1 Lothar Spillmann,3 and Wei Wang1 1Institute of Neuroscience, State Key Laboratory of Neuroscience, Key Laboratory of Primate Neurobiology, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China, 2University of Chinese Academy of Sciences, Shanghai 200031, China, and 3Department of Neurology, University of Freiburg, 79085 Freiburg, Germany Humans are more sensitive to luminance decrements than increments, as evidenced by lower thresholds and shorter latencies for dark stimuli. This asymmetry is consistent with results of neurophysiological recordings in dorsal lateral geniculate nucleus (dLGN) and primary visual cortex (V1) of cat and monkey. Specifically, V1 population responses demonstrate that darks elicit higher levels of activation than brights, and the latency of OFF responses in dLGN and V1 is shorter than that of ON responses. The removal of a dark or bright disc often generates the perception of a negative afterimage, and here we ask whether there also exist asymmetries for negative afterimages elicited by dark and bright discs. If so, do the poststimulus responses of subcortical ON and OFF cells parallel such afterimage asymmetries? To test these hypotheses, we performed psychophysical experiments in humans and single-cell/S-potential recordings in cat dLGN. Psychophysically, we found that bright afterimages elicited by luminance decrements are stronger and last longer than dark afterimages elicited by luminance increments of equal sizes. -
Embryology, Anatomy, and Physiology of the Afferent Visual Pathway
CHAPTER 1 Embryology, Anatomy, and Physiology of the Afferent Visual Pathway Joseph F. Rizzo III RETINA Physiology Embryology of the Eye and Retina Blood Supply Basic Anatomy and Physiology POSTGENICULATE VISUAL SENSORY PATHWAYS Overview of Retinal Outflow: Parallel Pathways Embryology OPTIC NERVE Anatomy of the Optic Radiations Embryology Blood Supply General Anatomy CORTICAL VISUAL AREAS Optic Nerve Blood Supply Cortical Area V1 Optic Nerve Sheaths Cortical Area V2 Optic Nerve Axons Cortical Areas V3 and V3A OPTIC CHIASM Dorsal and Ventral Visual Streams Embryology Cortical Area V5 Gross Anatomy of the Chiasm and Perichiasmal Region Cortical Area V4 Organization of Nerve Fibers within the Optic Chiasm Area TE Blood Supply Cortical Area V6 OPTIC TRACT OTHER CEREBRAL AREASCONTRIBUTING TO VISUAL LATERAL GENICULATE NUCLEUSPERCEPTION Anatomic and Functional Organization The brain devotes more cells and connections to vision lular, magnocellular, and koniocellular pathways—each of than any other sense or motor function. This chapter presents which contributes to visual processing at the primary visual an overview of the development, anatomy, and physiology cortex. Beyond the primary visual cortex, two streams of of this extremely complex but fascinating system. Of neces- information flow develop: the dorsal stream, primarily for sity, the subject matter is greatly abridged, although special detection of where objects are and for motion perception, attention is given to principles that relate to clinical neuro- and the ventral stream, primarily for detection of what ophthalmology. objects are (including their color, depth, and form). At Light initiates a cascade of cellular responses in the retina every level of the visual system, however, information that begins as a slow, graded response of the photoreceptors among these ‘‘parallel’’ pathways is shared by intercellular, and transforms into a volley of coordinated action potentials thalamic-cortical, and intercortical connections. -
Eye Essentials 5
continuing education 33 Eye essentials 5 Successful participation in each Classification and localisation module of this approved series counts as one credit towards the GOC CET scheme administered by Vantage and of visual field defects one towards the AOI’s scheme. In the last of our features based on the Eye Essential textbooks, Dr Robert Cubbidge describes the visual pathway and its relationship with the visual field. CET module C2354 This article has been adapted and abridged from Visual Fields by Dr THE DIMENSION of the blind spot Robert Cubbidge, is approximately 7.5º high and 5.5º wide part of the new and represents the temporal visual field Eye Essentials projection of the optic nerve, found series. For further approximately 1.5º below and 15º horizon- information, tally from fixation. When interpreting including ordering, please click on visual field defects, knowledge of the the Bookstore link arrangement of nerve fibres in the visual at www.optician pathway is essential. online.net Depending on the site of damage in the visual pathway, characteristic visual field defects are produced (Figure 1). course to the optic nerve as they are not Anatomically, the visual pathway hindered by the papillomacular bundle begins at the photoreceptors which lie in (Figure 2). The nerve fibres from the nasal the outer retina. Here, photons of light are retina do not cross those of the temporal absorbed by the photopigments, which are retina and thereby form a theoretical sensitive to specific regions of the visible vertical line of demarcation which passes electromagnetic spectrum. Light energy through the centre of the fovea. -
Anatomy and Physiology of the Afferent Visual System
Handbook of Clinical Neurology, Vol. 102 (3rd series) Neuro-ophthalmology C. Kennard and R.J. Leigh, Editors # 2011 Elsevier B.V. All rights reserved Chapter 1 Anatomy and physiology of the afferent visual system SASHANK PRASAD 1* AND STEVEN L. GALETTA 2 1Division of Neuro-ophthalmology, Department of Neurology, Brigham and Womens Hospital, Harvard Medical School, Boston, MA, USA 2Neuro-ophthalmology Division, Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA INTRODUCTION light without distortion (Maurice, 1970). The tear–air interface and cornea contribute more to the focusing Visual processing poses an enormous computational of light than the lens does; unlike the lens, however, the challenge for the brain, which has evolved highly focusing power of the cornea is fixed. The ciliary mus- organized and efficient neural systems to meet these cles dynamically adjust the shape of the lens in order demands. In primates, approximately 55% of the cortex to focus light optimally from varying distances upon is specialized for visual processing (compared to 3% for the retina (accommodation). The total amount of light auditory processing and 11% for somatosensory pro- reaching the retina is controlled by regulation of the cessing) (Felleman and Van Essen, 1991). Over the past pupil aperture. Ultimately, the visual image becomes several decades there has been an explosion in scientific projected upside-down and backwards on to the retina understanding of these complex pathways and net- (Fishman, 1973). works. Detailed knowledge of the anatomy of the visual The majority of the blood supply to structures of the system, in combination with skilled examination, allows eye arrives via the ophthalmic artery, which is the first precise localization of neuropathological processes. -
VISUAL FIELD Pathway Extends from the „Front‟ to the „Back‟ of the RETINA Brain
NOTE: To change the image on this slide, select the picture and delete it. Then click the Pictures icon in the placeholde r to insert your own image. Visual Pathway Disorders Amr Hassan, MD, FEBN Associate professor of Neurology - Cairo University Optic nerve • Anatomy of visual pathway • How to examine • Visual pathway disorders • Quiz 2 Optic nerve • Anatomy of visual pathway • How to examine • Visual pathway disorders • Quiz 3 Optic nerve The Visual Pathway VISUAL FIELD Pathway extends from the „front‟ to the „back‟ of the RETINA brain. ON OC OT LGN OPTIC RADIATIONS ON = Optic Nerve OC = Optic Chiasm OT = Optic Tract LGN = Lateral Geniculate Nucleus of Thalamus VISUAL CORTEX 5 The Visual Pathway Eyes & Retina Light >> lens >> retina (inverted and reversed image). Eyes & Retina Eyes & Retina • Macula: oval region approximately 3-5 mm that surrounds the fovea, also has high visual acuity. • Fovea: central fixation point of each eye// region of the retina with highest visual acuity. Eyes & Retina • Optic disc: region where axons leaving the retina gather to form the Optic nerve. Eyes & Retina • Blind spot located 15° lateral and inferior to central fixation point of each eye. Object to be seen Peripheral Retina Central Retina (fovea in the macula lutea) 12 Photoreceptors © Stephen E. Palmer, 2002 Photoreceptors Cones • Cone-shaped • Less sensitive • Operate in high light • Color vision • Less numerous • Highly represented in the fovea >> have high spatial & temporal resolution >> they detect colors. © Stephen E. Palmer, 2002 Photoreceptors Rods • Rod-shaped • Highly sensitive • Operate at night • Gray-scale vision • More numerous than cons- 20:1, have poor spatial & temporal resolution of visual stimuli, do not detect colors >> vision in low level lighting conditions © Stephen E. -
Functional Field of Vision
Functional Field of Vision Lea Hyvärinen Lea-Test Ltd, Apollonkatu 6 A 4, FIN-00100 Helsinki The size and the quality of visual field are important basic functions to be assessed as a part of functional vision assessment. Evaluation of functional field losses can be organized as follows: 1. Major field losses: A. Field losses due to pathway damage - half field loss, right, left remaining motion perception in ‘blind’ field half - quadrant losses B. Field losses due to disorders of the eyes - ROP - Congenital Glaucoma - Coloboma - Retinitis Pigmentosa and related disorders C. Central Scotoma 2. Minor field losses 3. Distortion of the image 4. Perceptual losses without measurable field loss 5. Restriction of functional visual field due to motor problems It may be wise to clarify some definitions: Anterior visual pathways contain eyes and the pathway up to the lateral geniculate nucleus (LGN), and posterior visual pathways contain the nerve fibres from the LGN to the primary visual cortex. Anterior visual impairment is due to damage to anterior pathways. Posterior visual impairment is due to damage to posterior visual pathways but may also be due to abnormal function in higher visual functions in the associative visual cortices without pathway damage. Information on visual field is given as drawings that depict the loss of function as it is projected onto the physical space around us. However, because central parts of visual field occupy much more cortical area in the primary visual cortex, they are magnified (= cortical magnification) in relation to the peripheral parts of the visual field (as illustrated in Figure 1). -
17-2021 CAMI Pilot Vision Brochure
Visual Scanning with regular eye examinations and post surgically with phoria results. A pilot who has such a condition could progress considered for medical certification through special issuance with Some images used from The Federal Aviation Administration. monofocal lenses when they meet vision standards without to seeing double (tropia) should they be exposed to hypoxia or a satisfactory adaption period, complete evaluation by an eye Helicopter Flying Handbook. Oklahoma City, Ok: US Department The probability of spotting a potential collision threat complications. Multifocal lenses require a brief waiting certain medications. specialist, satisfactory visual acuity corrected to 20/20 or better by of Transportation; 2012; 13-1. Publication FAA-H-8083. Available increases with the time spent looking outside, but certain period. The visual effects of cataracts can be successfully lenses of no greater power than ±3.5 diopters spherical equivalent, at: https://www.faa.gov/regulations_policies/handbooks_manuals/ techniques may be used to increase the effectiveness of treated with a 90% improvement in visual function for most One prism diopter of hyperphoria, six prism diopters of and by passing an FAA medical flight test (MFT). aviation/helicopter_flying_handbook/. Accessed September 28, 2017. the scan time. Effective scanning is accomplished with a patients. Regardless of vision correction to 20/20, cataracts esophoria, and six prism diopters of exophoria represent series of short, regularly-spaced eye movements that bring pose a significant risk to flight safety. FAA phoria (deviation of the eye) standards that may not be A Word about Contact Lenses successive areas of the sky into the central visual field. Each exceeded. -
Explore Your Blind Spot Discover How the Mind Hides Its
Explore your blind spot Discover how the mind hides its tracks by Tom Stafford Smashwords Edition (version 1.4, 2 July 2015) Copyright 2011 Tom Stafford This work is licensed under a Creative Commons Attribution-NonCommercial- ShareAlike 3.0 Unported License. Thank you for downloading this free eBook. You are welcome to share it with your friends. This book may be reproduced, copied and distributed for non-commercial purposes. You can even modify it, as long as the modified version is covered by the same licence. http://creativecommons.org/ Tom Stafford lives on the internet at http://idiolect.org.uk Follow him on twitter: @tomstafford Other ebooks by Tom: For argument’s sake: evidence that reason can change minds (2015) Control Your Dreams (2011) The Narrative Escape (2010) Your guide is Tom Stafford: This is a picture of the back of my eye, you can see the blood vessels and the optic disc, the light circle where they converge. It is this disc which produces the blind spots in our vision. You will need: pen, paper, eyes Your journey will take: minutes Category: perception Trig points: 3 The Treasure: Proud of your sharp sight? Perhaps you should think again. For each eye, there is a blind spot, an area near the middle of your vision for which you cannot see anything. Normally the way your vision works hides these blind spots from your awareness, but it isn't hard to show they're there. Visual blind spots are a good example of how our conscious experience is fundamentally based on our biological machinery.