Classroom Adaptations for Students with Low Vision”
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GUIDE for the Evaluation of VISUAL Impairment
International Society for Low vision Research and Rehabilitation GUIDE for the Evaluation of VISUAL Impairment Published through the Pacific Vision Foundation, San Francisco for presentation at the International Low Vision Conference VISION-99. TABLE of CONTENTS INTRODUCTION 1 PART 1 – OVERVIEW 3 Aspects of Vision Loss 3 Visual Functions 4 Functional Vision 4 Use of Scales 5 Ability Profiles 5 PART 2 – ASSESSMENT OF VISUAL FUNCTIONS 6 Visual Acuity Assessment 6 In the Normal and Near-normal range 6 In the Low Vision range 8 Reading Acuity vs. Letter Chart Acuity 10 Visual Field Assessment 11 Monocular vs. Binocular Fields 12 PART 3 – ESTIMATING FUNCTIONAL VISION 13 A General Ability Scale 13 Visual Acuity Scores, Visual Field Scores 15 Calculation Rules 18 Functional Vision Score, Adjustments 20 Examples 22 PART 4 – DIRECT ASSESSMENT OF FUNCTIONAL VISION 24 Vision-related Activities 24 Creating an Activity Profile 25 Participation 27 PART 5 – DISCUSSION AND BACKGROUND 28 Comparison to AMA scales 28 Statistical Use of the Visual Acuity Score 30 Comparison to ICIDH-2 31 Bibliography 31 © Copyright 1999 by August Colenbrander, M.D. All rights reserved. GUIDE for the Evaluation of VISUAL Impairment Summer 1999 INTRODUCTION OBJECTIVE Measurement Guidelines for Collaborative Studies of the National Eye Institute (NEI), This GUIDE presents a coordinated system for the Bethesda, MD evaluation of the functional aspects of vision. It has been prepared on behalf of the International WORK GROUP Society for Low Vision Research and Rehabilitation (ISLRR) for presentation at The GUIDE was approved by a Work Group VISION-99, the fifth International Low Vision including the following members: conference. -
425-428 YOSHI:Shoja
European Journal of Ophthalmology / Vol. 19 no. 3, 2009 / pp. 425-428 Effects of astigmatism on the Humphrey Matrix perimeter TOSHIAKI YOSHII, TOYOAKI MATSUURA, EIICHI YUKAWA, YOSHIAKI HARA Department of Ophthalmology, Nara Medical University, Nara - Japan PURPOSE. To evaluate the influence of astigmatism in terms of its amount and direction on the results of Humphrey Matrix perimetry. METHODS. A total of 31 healthy volunteers from hospital staff were consecutively recruited to undergo repeat testing with Humphrey Matrix 24-2 full threshold program with various induced simple myopic astigmatism. All subjects had previous experience (at least twice) with Matrix testing. To produce simple myopic astigmatism, a 0 diopter (D), +1 D, or +2 D cylindrical lens was added and inserted in the 180° direction and in the 90° direction after complete correction of distance vision. The influences of astigmatism were evaluated in terms of the mean deviation (MD), pattern standard deviation (PSD), and test duration (TD). RESULTS. A significant difference was observed only in the MD from five sessions. The MD in cases of 2 D inverse astigmatism was significantly lower than that in the absence of astig- matism. CONCLUSIONS. In patients with inverse myopic astigmatism of ≥ 2 D, the influences of astig- matism on the visual field should be taken into consideration when the results of Humphrey Matrix perimetry are evaluated. (Eur J Ophthalmol 2009; 19: 425-8) KEY WORDS. Astigmatism, Frequency doubling technology, FDT Matrix, Perimetry Accepted: October 10, 2008 INTRODUCTION as an FDT perimeter and became commercially available. In this perimeter, the examination time was shortened due Refractive error is one of the factors affecting the results to changes in the algorithm, the target size was made of perimetry. -
Binocular Vision Disorders Prescribing Guidelines
Prescribing for Preverbal Children Valerie M. Kattouf O.D. FAAO, FCOVD Illinois College of Optometry Associate Professor Prescribing for Preverbal Children Issues to consider: Age Visual Function Refractive Error Norms Amblyogenic Risk Factors Birth History Family History Developmental History Emmetropization A process presumed to be operative in producing a greater frequency of occurrence of emmetropia than would be expected in terms of chance distribution, as may be explained by postulating that a mechanism coordinates the formation and the development of the various components of the human eye which contribute to the total refractive power Emmetropization Passive process = nature and genetics 60% chance of myopia if 2 parents myopic (Ciuffrieda) Active process = mediated by blur and visual system compensates for blur Refractive Error Norms Highest rate of emmetropization – 1st 12-17 months Hyperopia Average refractive error in infants = +2 D > 1.50 diopters hyperopia at 5 years old – often remain hyperopic Refractive Error Norms Myopia 25% of infants are myopic Myopic Newborns (Scharf) @ 7 years 54% still myopic @ 7 years 46% emmetropic @ 7 years no hyperopia Refractive Error Norms Astigmatism Against the rule astigmatism more prevalent switches to with-the-rule with development At 3 1/2 years old astigmatism is at adult levels INFANT REFRACTION NORMS AGE SPHERE CYL 0-1mo -0.90+/-3.17 -2.02+/-1.43 2-3mo -0.47+/-2.28 -2.02+/-1.17 4-6mo -0.00+/-1.31 -2.20+/-1.15 6-9mo +0.50+/-0.99 -2.20+/-1.15 9-12mo +0.60+/-1.30 -1.64+/-0.62 -
Visual Performance of Scleral Lenses and Their Impact on Quality of Life In
A RQUIVOS B RASILEIROS DE ORIGINAL ARTICLE Visual performance of scleral lenses and their impact on quality of life in patients with irregular corneas Desempenho visual das lentes esclerais e seu impacto na qualidade de vida de pacientes com córneas irregulares Dilay Ozek1, Ozlem Evren Kemer1, Pinar Altiaylik2 1. Department of Ophthalmology, Ankara Numune Education and Research Hospital, Ankara, Turkey. 2. Department of Ophthalmology, Ufuk University Faculty of Medicine, Ankara, Turkey. ABSTRACT | Purpose: We aimed to evaluate the visual quality CCS with scleral contact lenses were 0.97 ± 0.12 (0.30-1.65), 1.16 performance of scleral contact lenses in patients with kerato- ± 0.51 (0.30-1.80), and 1.51 ± 0.25 (0.90-1.80), respectively. conus, pellucid marginal degeneration, and post-keratoplasty Significantly higher contrast sensitivity levels were recorded astigmatism, and their impact on quality of life. Methods: with scleral contact lenses compared with those recorded with We included 40 patients (58 eyes) with keratoconus, pellucid uncorrected contrast sensitivity and spectacle-corrected contrast marginal degeneration, and post-keratoplasty astigmatism who sensitivity (p<0.05). We found the National Eye Institute Visual were examined between October 2014 and June 2017 and Functioning Questionnaire overall score for patients with scleral fitted with scleral contact lenses in this study. Before fitting contact lens treatment to be significantly higher compared with scleral contact lenses, we noted refraction, uncorrected dis- that for patients with uncorrected sight (p<0.05). Conclusion: tance visual acuity, spectacle-corrected distance visual acuity, Scleral contact lenses are an effective alternative visual correction uncorrected contrast sensitivity, and spectacle-corrected contrast method for keratoconus, pellucid marginal degeneration, and sensitivity. -
Fact Sheet: Refractive Errors
Fact Sheet: Refractive Errors More than 11 million Americans have common vision problems that can be corrected with the use of prescriptive eyewear such as glasses or contact lenses.1 These conditions are known as refractive errors and they occur when the eye doesn’t correctly bend, or ―refract,‖ light as it enters the eye. Common refractive errors include the following: o Nearsightedness (also called myopia)—A condition where objects up close appear clearly, while objects far away appear blurry. With nearsightedness, light comes to focus in front of the retina instead of on the retina. o Farsightedness (also called hyperopia)—A common type of refractive error where distant objects may be seen more clearly than objects that are near. However, people experience farsightedness differently. Some people may not notice any problems with their vision, especially when they are young. For people with significant farsightedness, vision can be blurry for objects at any distance, near or far. o Astigmatism—A condition in which the eye does not focus light evenly onto the retina, the light-sensitive tissue at the back of the eye. This can cause images to appear blurry and stretched out. o Presbyopia—An age-related condition in which the ability to focus up close becomes more difficult. As the eye ages, the lens can no longer change shape enough to allow the eye to focus close objects clearly. Refractive errors are one of the most common—and correctable—causes of visual impairment in the United States. According to a recent study led by the National Eye Institute (NEI), approximately half of all American adults don’t have the 20/20 vision physicians consider optimal due to refractive errors.2 Women experience refractive error more frequently than men: Twenty-six percent more women aged 12 and older have uncorrected visual impairment due to refractive error compared with men aged 12 and older. -
Bass – Glaucomatous-Type Field Loss Not Due to Glaucoma
Glaucoma on the Brain! Glaucomatous-Type Yes, we see lots of glaucoma Field Loss Not Due to Not every field that looks like glaucoma is due to glaucoma! Glaucoma If you misdiagnose glaucoma, you could miss other sight-threatening and life-threatening Sherry J. Bass, OD, FAAO disorders SUNY College of Optometry New York, NY Types of Glaucomatous Visual Field Defects Paracentral Defects Nasal Step Defects Arcuate and Bjerrum Defects Altitudinal Defects Peripheral Field Constriction to Tunnel Fields 1 Visual Field Defects in Very Early Glaucoma Paracentral loss Early superior/inferior temporal RNFL and rim loss: short axons Arcuate defects above or below the papillomacular bundle Arcuate field loss in the nasal field close to fixation Superotemporal notch Visual Field Defects in Early Glaucoma Nasal step More widespread RNFL loss and rim loss in the inferior or superior temporal rim tissue : longer axons Loss stops abruptly at the horizontal raphae “Step” pattern 2 Visual Field Defects in Moderate Glaucoma Arcuate scotoma- Bjerrum scotoma Focal notches in the inferior and/or superior rim tissue that reach the edge of the disc Denser field defects Follow an arcuate pattern connected to the blind spot 3 Visual Field Defects in Advanced Glaucoma End-Stage Glaucoma Dense Altitudinal Loss Progressive loss of superior or inferior rim tissue Non-Glaucomatous Etiology of End-Stage Glaucoma Paracentral Field Loss Peripheral constriction Hereditary macular Loss of temporal rim tissue diseases Temporal “islands” Stargardt’s macular due -
Visual Pathways
Visual Pathways Michael Davidson Professor, Ophthalmology Diplomate, American College of Veterinary Ophthalmologists Department of Clinical Sciences College of Veterinary Medicine North Carolina State University Raleigh, North Carolina, USA <[email protected]> Vision in Animals Miller PE, Murphy CJ. Vision in Dogs. JAVMA. 1995; 207: 1623. Miller PE, Murphy CJ. Equine Vision. In Equine Ophthalmology ed. Gilger BC. 2nd ed. 2011: pp 398- 433. Ofri R. Optics and Physiology of Vision. In Veterinary Ophthalmology. ed. Gelatt KN 5th ed. 2013: 208-270, Visual Pathways, Responses and Reflexes: Relevant Structures Optic n (CN II) – somatic afferent Oculomotor n (CN III), Trochlear n (CN IV), Abducens n (CN VI) – somatic efferent to extraocular muscles Facial n (CN VII)– visceral efferent to eyelids Rostral colliculi – brainstem center that mediates somatic reflexes in response to visual stimuli Cerebellum Cerebro-cortex esp. occipital lobe www.studyblue.com Visual Pathway Visual Cortex Optic Radiation Lateral Geniculate Body www.studyblue.com Visual Field each cerebral hemisphere receives information from contralateral visual field (“the area that can be seen when the eye is directed forward”) visual field Visual Fiber (Retinotopic) Segregation nasal retinal fibers decussate at chiasm, temporal retinal fibers remain ipsilateral Nasal Temporal Retina Retina Fibers Fibers Decussate Remain Ipsilateral OD Visual Field OS Total visual field OD temporal nasal hemifield hemifield temporal nasal fibers fibers Nasal Temporal Retina = Retina = Temporal -
Visual Field Defects Essentials for Neurologists
J Neurol (2003) 250:407–411 DOI 10.1007/s00415-003-1069-1 REVIEW Ulrich Schiefer Visual field defects Essentials for neurologists Introduction I The visual pathway – a highly sensitive “functional trip-wire” The visual pathway achieves neuronal signal transduc- tion between retinal photoreceptors, visual cortex and higher order visual areas. Lesions affecting this “trip- wire” will result in visual impairment which should in- duce the affected person to contact a physician. Correct interpretation of such symptoms and choice of appro- priate psychophysical examination methods will usually provide the examiner with specific information on topography and eventual progression, if baseline results are available [3,6].These data are essential prerequisites for effective neuroimaging, as well as for an adequate follow-up. Fig. 1 Functional anatomy of the human visual pathways Functional anatomy of the human visual pathways About 7 million cones and approximately 120 million The different sections of the visual pathways differ rods are distributed on the human retinal surface (area markedly with respect to the number,density and extent ~ 12 cm2). Each retinal element is directly linked to a of “intermixture” of neuronal elements, which will specific location within the visual field. More than strongly influence local resolution power and diagnos- 10 million bipolar cells forward the visual information tic relevance (Fig. 1). onto only 1.2 million ganglion cells.These cells are wide- spread on the retinal surface, and converge to 300–500 fibre-bundles with a total surface area of less than Received: 18 January 2003 0.2 cm2. There is a maximum neuronal density in the re- Accepted: 30 January 2003 gion of the optic chiasm: the entire visual information is “packed” into this “visual bottleneck” of about 1 cm3! In Prof. -
Dominant Optic Atrophy
Lenaers et al. Orphanet Journal of Rare Diseases 2012, 7:46 http://www.ojrd.com/content/7/1/46 REVIEW Open Access Dominant optic atrophy Guy Lenaers1*, Christian Hamel1,2, Cécile Delettre1, Patrizia Amati-Bonneau3,4,5, Vincent Procaccio3,4,5, Dominique Bonneau3,4,5, Pascal Reynier3,4,5 and Dan Milea3,4,5,6 Abstract Definition of the disease: Dominant Optic Atrophy (DOA) is a neuro-ophthalmic condition characterized by a bilateral degeneration of the optic nerves, causing insidious visual loss, typically starting during the first decade of life. The disease affects primary the retinal ganglion cells (RGC) and their axons forming the optic nerve, which transfer the visual information from the photoreceptors to the lateral geniculus in the brain. Epidemiology: The prevalence of the disease varies from 1/10000 in Denmark due to a founder effect, to 1/30000 in the rest of the world. Clinical description: DOA patients usually suffer of moderate visual loss, associated with central or paracentral visual field deficits and color vision defects. The severity of the disease is highly variable, the visual acuity ranging from normal to legal blindness. The ophthalmic examination discloses on fundoscopy isolated optic disc pallor or atrophy, related to the RGC death. About 20% of DOA patients harbour extraocular multi-systemic features, including neurosensory hearing loss, or less commonly chronic progressive external ophthalmoplegia, myopathy, peripheral neuropathy, multiple sclerosis-like illness, spastic paraplegia or cataracts. Aetiology: Two genes (OPA1, OPA3) encoding inner mitochondrial membrane proteins and three loci (OPA4, OPA5, OPA8) are currently known for DOA. Additional loci and genes (OPA2, OPA6 and OPA7) are responsible for X-linked or recessive optic atrophy. -
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. -
Analysis of Tear Film Spatial Instability for Pediatric Myopia Under Treatment
www.nature.com/scientificreports OPEN Analysis of tear flm spatial instability for pediatric myopia under treatment Wan‑Hua Cho, Po‑Chiung Fang, Hun‑Ju Yu, Pei‑Wen Lin, Hsiu‑Mei Huang & Ming‑Tse Kuo * In Taiwan, the prevalence of myopia in children between 6 and 18 years old is over 80%, and high myopia accounts for over 20%, which turned out to be in the leading place worldwide. Orthokeratology and low-dose atropine are proven treatments to reduce myopia progression, though the potential corneal disturbances remain an issue in young populations. The alteration of the tear flm is widely discussed but there is no consensus to date, so we aim to investigate the tear flm spatial instability in children with myopia control using atropine or orthokeratology. Thirty-eight treatment-naïve participants and 126 myopic children under treatments were enrolled. The ocular surface homeostasis, spatial distribution of tear break-up, and high-order aberrations (HOAs) of the corneal surface were assessed. We found out that myopic children treated with either atropine or orthokeratology showed ocular surface homeostasis similar to that in treatment-naïve children. Nevertheless, children treated with orthokeratology presented higher HOAs (p < 0.00001) and a tendency of the frst tear break-up zone at the inner half of the cornea (p = 0.04). This unique spatial instability of the tear flm associated with myopia treatment might provide a more focused way of monitoring the pediatric tear flm instability. Many studies have revealed diferences in the prevalence of myopia across diferent regions and ethnicities, and the increased rate of myopia is most prominent in Asian/Pacifc children1,2. -
Visual Impairment 101: What Do Administrators Need to Know?
Visual Impairment 101: What do Administrators Need to Know? Stephanie Walker, ESC Region 11 Mary Shore, TSBVI Outreach Visual Impairment 101 What do administrators need to know? Presented by: Stephanie Walker, M.Ed. Lead for the State Leadership Services for the Blind and Visually Impaired (SLSBVI) Network Mary Shore, COMS Professional Preperation Coordinator TSBVI Outreach Handouts and Additional Resources Texas School for the Blind and Visually Impaired - Administrator’s Toolbox Statewide Leadership Services for the Blind and Visually Impaired Simulation Activities What is a visual impairment? §300.8 (c)(13) Visual impairment including blindness means an impairment in vision that, even with correction, adversely affects a child’s educational performance. The term includes both partial sight and blindness. §89.1040 (c)(12) (A) A student with a visual impairment is one who has been determined to meet the criteria for visual impairment as stated in 34 CFR, §300.8(c)(13). The visual loss should be stated in exact measures of visual field and corrected visual acuity at a distance and at close range in each eye in a report by a licensed ophthalmologist or optometrist. The report should also include prognosis whenever possible. If exact measures cannot be obtained, the eye specialist must so state and provide best estimates. What types of vision does this include? Legally Blind Central vision acuity in the better eye of 20/200 or worse after the best correction possible, or a field of vision of 20 degrees or less. Low Vision/Partial sight Visual acuity better than 20/200 after correction in the better eye.