Neural Correlates of Convergence Eye Movements in Convergence Insufficiency Patients Vs
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Article • a Case Series in Optometric Management of Diverse Vertical
Article • A Case Series in Optometric Management of Diverse Vertical Deviations Darah McDaniel-Chandler, OD • Southern College of Optometry Memphis, Tennessee ABSTRACT Background: Vertical deviations present in diverse patient populations with a multitude of puzzling symptoms and complaints. Many patients with vertical deviations have visited numerous doctors looking for an explanation for their symptoms of dizziness, headaches, motion sickness, and double vision. Vertical deviations may be apparent in the clinical optometric exam sequence, but at other times, additional testing must be performed to uncover a vertical heterophoria, including fixation disparity, vertical vergences, a period of diagnostic occlusion, or Maddox rod. Case Report: Three case reports are reviewed with diverse presentations of vertical deviations. The first case report outlines Patient A, a 51-year-old female who presented with dizziness along with a latent hyperphoria that was not apparent on the initial clinical examination. The second case report outlines Patient B, a 52-year-old female who presented with a longstanding large-angle vertical strabismus with strabismic amblyopia in the right eye. The third case report outlines Patient C, a 61-year-old female who presented with intermittent vertical diplopia following a cerebrovascular accident. The three cases all underwent vision therapy or vision therapy in combination with prismatic correction, and all three cases experienced symptom reduction following treatment with optometric vision rehabilitation. Conclusion: -
Teacher Guide
Neuroscience for Kids http://faculty.washington.edu/chudler/neurok.html. Our Sense of Sight: Part 2. Perceiving motion, form, and depth Visual Puzzles Featuring a “Class Experiment” and “Try Your Own Experiment” Teacher Guide WHAT STUDENTS WILL DO · TEST their depth perception using one eye and then two · CALCULATE the class averages for the test perception tests · DISCUSS the functions of depth perception · DEFINE binocular vision · IDENTIFY monocular cues for depth · DESIGN and CONDUCT further experiments on visual perception, for example: · TEST people’s ability to interpret visual illusions · CONSTRUCT and test new visual illusions · DEVISE a “minimum difference test” for visual attention 1 SETTING UP THE LAB Supplies For the Introductory Activity Two pencils or pens for each student For the Class Experiment For each group of four (or other number) students: Measuring tools (cloth tape or meter sticks) Plastic cups, beakers or other sturdy containers Small objects such as clothespins, small legos, paper clips For “Try Your Own Experiment!” Visual illusion figures, found at the end of this Teacher Guide Paper and markers or pens Rulers Other Preparations · For the Class Experiment and Do Your Own Experiment, students can write results on a plain sheet of paper. · Construct a chart on the board where data can be entered for class discussion. · Decide the size of the student groups; three is a convenient number for these experiments—a Subject, a Tester, and a Recorder. Depending on materials available, four or five students can comprise a group. · For “Try Your Own Experiment!,” prepare materials in the Supply list and put them out on an “Explore” table. -
Visual Secret Sharing Scheme with Autostereogram*
Visual Secret Sharing Scheme with Autostereogram* Feng Yi, Daoshun Wang** and Yiqi Dai Department of Computer Science and Technology, Tsinghua University, Beijing, 100084, China Abstract. Visual secret sharing scheme (VSSS) is a secret sharing method which decodes the secret by using the contrast ability of the human visual system. Autostereogram is a single two dimensional (2D) image which becomes a virtual three dimensional (3D) image when viewed with proper eye convergence or divergence. Combing the two technologies via human vision, this paper presents a new visual secret sharing scheme called (k, n)-VSSS with autostereogram. In the scheme, each of the shares is an autostereogram. Stacking any k shares, the secret image is recovered visually without any equipment, but no secret information is obtained with less than k shares. Keywords: visual secret sharing scheme; visual cryptography; autostereogram 1. Introduction In 1979, Blakely and Shamir[1-2] independently invented a secret sharing scheme to construct robust key management scheme. A secret sharing scheme is a method of sharing a secret among a group of participants. In 1994, Naor and Shamir[3] firstly introduced visual secret sharing * Supported by National Natural Science Foundation of China (No. 90304014) ** E-mail address: [email protected] (D.S.Wang) 1 scheme in Eurocrypt’94’’ and constructed (k, n)-threshold visual secret sharing scheme which conceals the original data in n images called shares. The original data can be recovered from the overlap of any at least k shares through the human vision without any knowledge of cryptography or cryptographic computations. With the development of the field, Droste[4] provided a new (k, n)-VSSS algorithm and introduced a model to construct the (n, n)-combinational threshold scheme. -
Stereoscopic Therapy: Fun Or Remedy?
STEREOSCOPIC THERAPY: FUN OR REMEDY? SARA RAPOSO Abstract (INDEPENDENT SCHOLAR , PORTUGAL ) Once the material of playful gatherings, stereoscop ic photographs of cities, the moon, landscapes and fashion scenes are now cherished collectors’ items that keep on inspiring new generations of enthusiasts. Nevertheless, for a stereoblind observer, a stereoscopic photograph will merely be two similar images placed side by side. The perspective created by stereoscop ic fusion can only be experienced by those who have binocular vision, or stereopsis. There are several caus es of a lack of stereopsis. They include eye disorders such as strabismus with double vision. Interestingly, stereoscopy can be used as a therapy for that con dition. This paper approaches this kind of therapy through the exploration of North American collections of stereoscopic charts that were used for diagnosis and training purposes until recently. Keywords. binocular vision; strabismus; amblyopia; ste- reoscopic therapy; optometry. 48 1. Binocular vision and stone (18021875), which “seem to have access to the visual system at the same stereopsis escaped the attention of every philos time and form a unitary visual impres opher and artist” allowed the invention sion. According to the suppression the Vision and the process of forming im of a “simple instrument” (Wheatstone, ory, both similar and dissimilar images ages, is an issue that has challenged 1838): the stereoscope. Using pictures from the two eyes engage in alternat the most curious minds from the time of as a tool for his study (Figure 1) and in ing suppression at a low level of visual Aristotle and Euclid to the present day. -
Relative Importance of Binocular Disparity and Motion Parallax for Depth Estimation: a Computer Vision Approach
remote sensing Article Relative Importance of Binocular Disparity and Motion Parallax for Depth Estimation: A Computer Vision Approach Mostafa Mansour 1,2 , Pavel Davidson 1,* , Oleg Stepanov 2 and Robert Piché 1 1 Faculty of Information Technology and Communication Sciences, Tampere University, 33720 Tampere, Finland 2 Department of Information and Navigation Systems, ITMO University, 197101 St. Petersburg, Russia * Correspondence: pavel.davidson@tuni.fi Received: 4 July 2019; Accepted: 20 August 2019; Published: 23 August 2019 Abstract: Binocular disparity and motion parallax are the most important cues for depth estimation in human and computer vision. Here, we present an experimental study to evaluate the accuracy of these two cues in depth estimation to stationary objects in a static environment. Depth estimation via binocular disparity is most commonly implemented using stereo vision, which uses images from two or more cameras to triangulate and estimate distances. We use a commercial stereo camera mounted on a wheeled robot to create a depth map of the environment. The sequence of images obtained by one of these two cameras as well as the camera motion parameters serve as the input to our motion parallax-based depth estimation algorithm. The measured camera motion parameters include translational and angular velocities. Reference distance to the tracked features is provided by a LiDAR. Overall, our results show that at short distances stereo vision is more accurate, but at large distances the combination of parallax and camera motion provide better depth estimation. Therefore, by combining the two cues, one obtains depth estimation with greater range than is possible using either cue individually. -
Care of the Patient with Accommodative and Vergence Dysfunction
OPTOMETRIC CLINICAL PRACTICE GUIDELINE Care of the Patient with Accommodative and Vergence Dysfunction OPTOMETRY: THE PRIMARY EYE CARE PROFESSION Doctors of optometry are independent primary health care providers who examine, diagnose, treat, and manage diseases and disorders of the visual system, the eye, and associated structures as well as diagnose related systemic conditions. Optometrists provide more than two-thirds of the primary eye care services in the United States. They are more widely distributed geographically than other eye care providers and are readily accessible for the delivery of eye and vision care services. There are approximately 36,000 full-time-equivalent doctors of optometry currently in practice in the United States. Optometrists practice in more than 6,500 communities across the United States, serving as the sole primary eye care providers in more than 3,500 communities. The mission of the profession of optometry is to fulfill the vision and eye care needs of the public through clinical care, research, and education, all of which enhance the quality of life. OPTOMETRIC CLINICAL PRACTICE GUIDELINE CARE OF THE PATIENT WITH ACCOMMODATIVE AND VERGENCE DYSFUNCTION Reference Guide for Clinicians Prepared by the American Optometric Association Consensus Panel on Care of the Patient with Accommodative and Vergence Dysfunction: Jeffrey S. Cooper, M.S., O.D., Principal Author Carole R. Burns, O.D. Susan A. Cotter, O.D. Kent M. Daum, O.D., Ph.D. John R. Griffin, M.S., O.D. Mitchell M. Scheiman, O.D. Revised by: Jeffrey S. Cooper, M.S., O.D. December 2010 Reviewed by the AOA Clinical Guidelines Coordinating Committee: David A. -
Binocular Vision
BINOCULAR VISION Rahul Bhola, MD Pediatric Ophthalmology Fellow The University of Iowa Department of Ophthalmology & Visual Sciences posted Jan. 18, 2006, updated Jan. 23, 2006 Binocular vision is one of the hallmarks of the human race that has bestowed on it the supremacy in the hierarchy of the animal kingdom. It is an asset with normal alignment of the two eyes, but becomes a liability when the alignment is lost. Binocular Single Vision may be defined as the state of simultaneous vision, which is achieved by the coordinated use of both eyes, so that separate and slightly dissimilar images arising in each eye are appreciated as a single image by the process of fusion. Thus binocular vision implies fusion, the blending of sight from the two eyes to form a single percept. Binocular Single Vision can be: 1. Normal – Binocular Single vision can be classified as normal when it is bifoveal and there is no manifest deviation. 2. Anomalous - Binocular Single vision is anomalous when the images of the fixated object are projected from the fovea of one eye and an extrafoveal area of the other eye i.e. when the visual direction of the retinal elements has changed. A small manifest strabismus is therefore always present in anomalous Binocular Single vision. Normal Binocular Single vision requires: 1. Clear Visual Axis leading to a reasonably clear vision in both eyes 2. The ability of the retino-cortical elements to function in association with each other to promote the fusion of two slightly dissimilar images i.e. Sensory fusion. 3. The precise co-ordination of the two eyes for all direction of gazes, so that corresponding retino-cortical element are placed in a position to deal with two images i.e. -
Strabismus: a Decision Making Approach
Strabismus A Decision Making Approach Gunter K. von Noorden, M.D. Eugene M. Helveston, M.D. Strabismus: A Decision Making Approach Gunter K. von Noorden, M.D. Emeritus Professor of Ophthalmology and Pediatrics Baylor College of Medicine Houston, Texas Eugene M. Helveston, M.D. Emeritus Professor of Ophthalmology Indiana University School of Medicine Indianapolis, Indiana Published originally in English under the title: Strabismus: A Decision Making Approach. By Gunter K. von Noorden and Eugene M. Helveston Published in 1994 by Mosby-Year Book, Inc., St. Louis, MO Copyright held by Gunter K. von Noorden and Eugene M. Helveston All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission from the authors. Copyright © 2010 Table of Contents Foreword Preface 1.01 Equipment for Examination of the Patient with Strabismus 1.02 History 1.03 Inspection of Patient 1.04 Sequence of Motility Examination 1.05 Does This Baby See? 1.06 Visual Acuity – Methods of Examination 1.07 Visual Acuity Testing in Infants 1.08 Primary versus Secondary Deviation 1.09 Evaluation of Monocular Movements – Ductions 1.10 Evaluation of Binocular Movements – Versions 1.11 Unilaterally Reduced Vision Associated with Orthotropia 1.12 Unilateral Decrease of Visual Acuity Associated with Heterotropia 1.13 Decentered Corneal Light Reflex 1.14 Strabismus – Generic Classification 1.15 Is Latent Strabismus -
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. -
Etiology of Heterophoria and Heterotropia
CHAPTER 9 Etiology of Heterophoria and Heterotropia n heterophoria there is a relative deviation of Factors Responsible for the Ithe visual axes held in check by the fusion Manifestation of a Deviation mechanism, whereas in heterotropia there is a manifest deviation of the visual axes. The relative Abnormalities of Fusion Mechanism position of the visual axes is determined by the equilibrium or disequilibrium of forces that keep DEFECT OF MOTOR FUSION IN INFANTILE ES- the eyes properly aligned and of forces that disrupt OTROPIA. Motor fusion in patients with hetero- this alignment. Clearly, the fusion mechanism and phoria is adequate to maintain a proper alignment its anomalies are involved in some manner in of the eyes. This does not mean that patients with producing comitant heterotropias. To understand a heterophoria necessarily have normal sensory the etiology of neuromuscular anomalies of the fusion. In those with higher degrees of heteropho- eyes, therefore, one should also gain an insight ria, suppression and a high stereoscopic threshold into other factors that determine the relative posi- may be present, but motor responses are sufficient tion of the visual axes. to keep the eyes aligned. In heterotropia this is First, there are anatomical factors, which con- not the case. These circumstances have led to a sist of orientation, size, and shape of the orbits; theory of the etiology of strabismus developed by size and shape of the globes; volume and viscosity Worth in 1903 in his famous book on squint.156 of the retrobulbar tissue; functioning of the eye His theory was that the essential cause of squint muscles as determined by their insertion, length, is a defect of the fusion faculty156, p. -
Persistent Strabismus After Cataract Extraction
Број 9 ВОЈНОСАНИТЕТСКИ ПРЕГЛЕД Страна 689 UDC: 617.741−004.1−089.168.1−06 CASE REPORT Persistent strabismus after cataract extraction Mirjana P. Dujić*, Katarina R. Misailović*, Milena M. KovačeviㆠClinical Center Zvezdara, *Department of Ophthalmology, †Center of Anesthesiology and Reanimation, Belgrade Background. Transient ocular misalignment as a complication of parabulbar and peribul- bar anesthesia has already been reported in the literature. The aim of our study was to pre- sent a case of irreversible iatrogenic vertical strabismus after cataract surgery, which had to be operated on. Methods. Clinical and orthoptic evaluation of a female patient with ver- tical diplopia after phacoemulsification cataract surgery. Results. One week after the un- eventful surgery, a 68-year-old patient complained of a sudden vertical deviation in the op- erated eye. The patient had not had a history of previous motility disorders. On examina- tion, the patient showed hypertropia in the left eye of 15−20 degrees in primary position. Three and 6 months postoperatively, there was no a spontaneous improvement, while the persistent vertical deviation was 40 prism dioptres. Strabismus surgery was required 1 year after the cataract surgery. Conclusion. Diplopia is a complication of peribulbar an- esthesia which could be persistent. The superior and inferior rectus muscle are especially vulnerable. Its occurrence may be technique - related and the incidence increases when hyaluronidase is not available. K e y w o r d s : cataract extraction; diplopia; anesthesia, local; enzymes; strabismus; iatrogenic disease. Introduction the clinic during a 2-year-period when hyaluronidase was not available. Diplopia is an infrequent, but well-known complica- A 68-year-old woman had uneventful phacoemulsifi- tion after cataract surgery (1, 2) Postoperative misalignment cation cataract surgery with a posterior chamber intraocular may result from many mechanisms, some of which are the lens (PCIOL) implantation in the left eye. -
GAZE and AUTONOMIC INNERVATION DISORDERS Eye64 (1)
GAZE AND AUTONOMIC INNERVATION DISORDERS Eye64 (1) Gaze and Autonomic Innervation Disorders Last updated: May 9, 2019 PUPILLARY SYNDROMES ......................................................................................................................... 1 ANISOCORIA .......................................................................................................................................... 1 Benign / Non-neurologic Anisocoria ............................................................................................... 1 Ocular Parasympathetic Syndrome, Preganglionic .......................................................................... 1 Ocular Parasympathetic Syndrome, Postganglionic ........................................................................ 2 Horner Syndrome ............................................................................................................................. 2 Etiology of Horner syndrome ................................................................................................ 2 Localizing Tests .................................................................................................................... 2 Diagnosis ............................................................................................................................... 3 Flow diagram for workup of anisocoria ........................................................................................... 3 LIGHT-NEAR DISSOCIATION .................................................................................................................