All You Ever Wanted to Know About ERG but Were Afraid to Ask

Slides:



Advertisements
Similar presentations
The Scotopic ERG Response A dim flash of light below the sensitivity threshold for cone photoreceptors stimulates only the rods in a dark adapted eye.
Advertisements

E.R.G : Measure the electrical responses of various cell types in the retina. Including : The photoreceptors (rods and cones ) Inner retinal cells (bipolar.
Functional Testing of the Eye: Clinical Electrophysiology of Vision Matthew L. Severns, Ph.D. LKC Technologies, Inc. USA.
بنام خداوند بخشنده مهربان دکتر غلامعلی نادریان گروه چشم گروه چشم دانشگاه علوم پزشکی اصفهان.
Applications of ERG, mfERG & EOG
Photoreceptors.
Conclusions This study shows that it is possible to obtain a normal or abnormal EALR when there is an abnormal EOGLR. This would support the theory that.
ELECTRO-OCULOGRAPHY Dr S R Pati.
RGB Models human visual system? Gives an absolute color description? Models color similarity? Linear model? Convenient for color displays?
1 Testing sensory visual function. 2 types: 1) psychophysical tests 2) electrophysical tests.
Vision By: Bethany, Iqra, Clint, Cameron, Nick. The Process Light enters eye through the cornea Then, it goes through the pupil which is surrounded by.
VERIS ™ by Electro-Diagnostic Imaging, Inc. Redwood City, California, USA First in Multifocal Electrophysiology and its Future.
Visual Electrodiagnostic Testing-8 Mutez Gharaibeh,MD.
 sensory transduction ◦ - conversion of physical energy from the environment into changes in electrical potential  sensory coding- ◦ Making sense.
1 Perception, Illusion and VR HNRS , Spring 2008 Lecture 3 The Eye.
VERIS ™ by Electro-Diagnostic Imaging, Inc
Vision Structure of the Eye We only use light energy to see.
The Visual System: Retinal Mechanisms
1 Computational Vision CSCI 363, Fall 2012 Lecture 5 The Retina.
ElectroRetinoGraphy Jahanzeb ee Fatima Rafique ee
1 Perception and VR MONT 104S, Fall 2008 Lecture 2 The Eye.
Glaucoma Care Project Team Members: Geoffrey T. Emerick, M.D. Erin Herlihy, B.S. Marilyn Hauser, M.B.A. Dianna Greening, R.N. Walter M. Jay, M.D Opportunity.
Chapter 36 Sensory Reception.
Electroretinogram: An electrical diagnostic test of retinal function in situ n Electro -part –Currents, wires, voltage, resistance n Retino - part –Cell.
The Retina and Fovea Rods and Cones Light & Dark Adaptation Blind Spot, Blood Vessels The Fovea and Acuity.
Nathan Lighthizer, O.D., F.A.A.O Assistant Professor, NSUOCO Chief of Specialty Care Clinics Chief of Electrodiagnostics Clinic COPE Approved: COPE # PD.
Nathan Lighthizer, O.D., F.A.A.O Assistant Professor, NSUOCO Chief of Specialty Care Clinics Chief of Electrodiagnostics Clinic COPE Approved: COPE # PD.
Using the portable HMsERG unit for assessment of retinal function in
Physiology-II PHL-226 Physiology of vision
Vision- How do we see what we see?
Mumbaieyecarecornealasik.com.
Cone-Rod Dystrophy: a rare disorder of the eye that is usually, but not always, inherited. The cells that receive light stimuli (cone cells and rod cells)
Light Sensing and Vision
Transduction Transformation of stimulus energies to electrochemical energy of neural impulses Sensory receptors are responsible for transduction Rods and.
Special Senses Chapter 8.
Invest. Ophthalmol. Vis. Sci ;45(3): doi: /iovs Figure Legend:
Mr. Koch AP Psychology Forest Lake High School
BY DR. MUDASSAR ALI ROOMI (MBBS, M. Phil.)
Sensation and Perception
INPUT-OUTPUT CHANNELS
Journal #3: Which 3 cranial nerves monitor the tongue?
Vision Seeing is Believing.
Wednesday, 19 September Organisms respond to changes in their internal and external environments Eye Receptors • identify the pigments.
Chapter 6 Sensation and Perception
General Anatomy of the Eye & Degenerative Diseases of Human Retina
Eyes & Vision.
Electro-physiology 14/11/2018.
بنام خداوند بخشنده مهربان
THE EYES AND VISION.
The Visual System: Retinal Mechanisms
VISION Module 18.
Loai Alzghoul
HISTOLOGY OF CORNEA & RETINA
Visual processing: The Devil is in the details
A Nonsense Mutation in PDE6H Causes Autosomal-Recessive Incomplete Achromatopsia  Susanne Kohl, Frauke Coppieters, Françoise Meire, Simone Schaich, Susanne.
Vision Our most dominating sense. Visual Capture.
Alloimmune Retinopathy Associated with Antibodies to Transducin-α as a Complication of Chronic Graft-Versus-Host Disease  William Wood, Seema Garg, Grazyna.
Changing Light Waves to Neural Impulses
The Challenges Natural Images Pose for Visual Adaptation
Computational Vision CSCI 384, Spring 2004 Lecture 4 The Retina
Retinitis Pigmentosa Course Title : Molecular diagnostic Unit : II
Posterior part of the eye Review
Outline Announcements Human Visual Information Processing
An evaluation of current UK practice for Evoked Potentials - VEP
Eye: Retina and Neural Mechanisms.
Regeneration: New Neurons Wire Up
Special Senses Visual Sense.
Volume 12, Issue 3, Pages (February 2002)
Electrophysiologic Testing Index
CHAPTER 3 SENSATION.
Presentation transcript:

All You Ever Wanted to Know About ERG but Were Afraid to Ask American Academy of Ophthalmology, Orlando, 2002 10 November 2018

Testing Levels of the Visual System clinical neurophysiology allows assessment of retina, optic nerve, chiasm, and retrochiasmal visual pathways the ERG can functionally dissect the neural retina 10 November 2018

Electroretinogram (ERG) ERGs are mass electrical activity from the retina in response to visual stimulation the ERG is objective, non-invasive measure of electroretinal function OD OS a b 100 Uv 25 ms 10 November 2018

Recording the ERG Photic stimulator Plotter electrode

Microconductive Thread ERG Electrodes Contact Lens Electrode Microconductive Thread Electrode 10 November 2018

Modern ERG Recording Electrodes DTL-Plus™ Microconductive Thread Electrode 10 November 2018

ERG Electrodes Microconductive thread electrode neglible mass convenient to use, disposable no interference with pupil or optics reliable ERG recordings well tolerated by children Microconductive thread electrode 10 November 2018

Pre-Millenium ERG Technology Ganzfeld Stimulation (full-field) provided by xenon flash photostimulator full visual field stimulation stimulus intensity stimulus wavelength variable stimulus rate variable background intensity 10 November 2018

Modern ERG Stimulator 10 November 2018

Mini-Ganzfeld LED Stimulator 4.5 inch diameter 176 LEDs “blue” (470 nm) “green” (525 nm) “red” (640 nm) 7 log unit luminance range optoelectronic stimulation can be more precisely controlled and calibrated than xenon discharge tubes Espion Colorburst™ 10 November 2018

Components of the Flash ERG 11/10/2018 Components of the Flash ERG b-wave Implicit time (i.t.)= time from stimulus until peak of activity b i.t. Amplitude (amp)= voltage magnitude at peak of activity b amp a amp a i.t. a-wave

Generator Sites of the Flash ERG a-wave originates from the photoreceptor layer b-wave is a glial potential originating from the Müller cell and the bipolar cells OPs originate from amacrine cells flash ERG reflects electroretinal activity distal to the ganglion cell layer 10 November 2018

Oscillatory Potentials (OP) OD OS 5 Uv 15 ms a subcomponent of the ERG seen on ascending limb of the b-wave Wachtmeister (1977) demonstrated OPs originate from amacrine cells in the inner plexiform layer 10 November 2018

Rod vs Cone ERGs Rod ERG OPs Cone ERG 30 Hz Flicker 10 November 2018

Pattern ERG (PERG) Elicited to pattern stimulation (usually checkerboard or bar gratings) much lower amplitude than flash ERGs fixation is critical for PERG, not flash ERG PERG reflects activity in the ganglion cell layer 10 November 2018

Generators of the Pattern ERG PERGs are generated in the ganglion cell layer PERGs may reflect both activation of cell body and axonal activity 10 November 2018

ISCEV ERG Standards International Society for Clinical Electrophysiology of Vision (ISCEV) ERG standard established in 1989 standards for 5 commonly obtained responses ERG developed by the rods (dark-adapted) maximal ERG response (dark-adapted) Oscillatory Potentials ERG developed by the cones (light-adapted) ERG to flicker 10 November 2018

Who are the Clients of an Electrodiagnostic Service? Patients whose eyes have: symptoms suggestive of known neurological or ophthalmological disease unexplained visual loss medico-legal problems workman’s compensation defects associated with psychiatric disturbance, mental or physical handicap pediatric neuro-ophthalmic practice metabolic, hereditary or neurological disease with visual impairment non-seeing child 10 November 2018

Who are the Clients of an Electrodiagnostic Service? Patients with media opacities prior to corneal grafting or cataract surgery vitreous hemorrhage (in DR or following trauma, RD) Patients with uveitis or inflammatory eye disease Patients with suspected disease or carrier status of inherited visual disorders Patients requiring quantitative assessment of disease progression Assessment of retinal and optic nerve function following trauma 10 November 2018

Indications for ERG aid to diagnosis in patients suspected of having stationary or progressive inherited retinal degenerations to rule out clinically unaffected family members to evaluate possible female carriers of x-linked disease to assess patients with retinal toxicity due to metallosis (siderosis) retinotoxic or neurotoxic medications chloroquine, Hydroxychloroquine, ethambutol, phenothiazine Desferrioxamine, Tamoxifen Vigabatrin toxicity? patients with OHT/glaucoma to identify eyes that are likely to develop neovascularization in diseases such as CRVO and DR documenting therapeutic effects of surgery or medication 10 November 2018

Electrodiagnostics of the Future Standardized instrumentation Standardized testing protocols Multicenter normative data collection Web-based telemedicine application University of Ottawa Eye Institute announces ERG Reading Centre 10 November 2018