DOCSLIB.ORG

Visual Acuity Assessment

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Visual Acuity Assessment VISUAL ACUITY ASSESSMENT J. R. WEATHERILL Bradford Tests of visual function in cataract patients are performed recognised that patients with macular dysfunction have in order to answer two questions: (I) To what extent is the difficulty in reading out of proportion to their Snellen cataract responsible for the patient's symptoms? (2) Will acuity. This difficultyis probably due to parafoveal scoto­ removal of the cataract improve the patient's sight? To mas which prevent the whole word being seen at the same answer the firstquestion the optical qualities of the eye are time. If a patient reports that the main problem is with assessed, and to answer the second tests are employed reading, it is helpful to observe whether the patient holds which assess retinal and neural function and which are the page steadily or keeps moving it to avoid scotomas. relatively unaffected by the optical degradation caused by With current reading tests patients with poor macular opacities in the media. At Bradford we employ the tests function can read small print for brief periods, particularly listed in Table I. if they are used to reading and recognise the overall shape of the words. A Logmar equivalent for near vision com­ Snellen Acuity prising random words of equal length and composed of Although the Snellen acuity test measures the function of letters without either ascenders or descenders, read under only the central 1_20 in monochrome at 100% contrast, it controlled conditions of illumination and at a standard dis­ is nonetheless the 'gold standard' by which ophthal­ tance, would provide a more accurate measure of macular mologists judge and are judged. It is universally recog­ function. It would possibly also be helpful in the manage­ nised and enjoys a legal status. Despite its limitations, in ment of conditions such as diabetic maculopathY in which the vast majority of patients the pattern and degree of cat­ patients often report improvement in near vision after aract are consistent with the Snellen acuity which experi­ treatment although the Snellen acuity is little altered. ence has taught us to expect, and the decision as to Contrast Sensitivity whether to operate or not is straightforward. In a minority of patients the Snellen actuity does not correspond with For many years contrast sensitivity has been a research the observed degree of cataract. If the acuity is worse than tool and each department has devised its own techniques, expected, retinal function tests are employed; if the Snel­ but for clinical purposes the Pelli-Robson chart, in which len acuity is much better than the patient's symptoms letters of uniform size are displayed in decreasing con­ would suggest, tests of the optical system may demon­ trast, gives reproducible results. High-frequency closely strate the cause of the difficulties. spaced lines can only be seen at high contrast and this is A more accurate form of the Snellen chart is the Ferris­ equivalent to the Snellen acuity. Low-frequency lines can Bailey Logmar1 chart, which we have used for monitoring be seen with less contrast. A high degree of contrast sensi­ the progress of cataract. Its features are: (1) there are an tivity from low to high frequency is essential for normal equal number of letters on each line, (2) the letters have vision. One of the most important functions of sight is to been chosen for equal legibility, (3) the increase in size of recognise faces. One of the commonest complaints of cat- the letters is on a logarithmic scale, and (4) the working Table I. Tests of visual function used at Bradford distance is 4 m. This chart is widely used in vision research and is no more difficult for the patient than the Optical test Retinal test Snellen chart. In the interests of reproducibility and accu­ Snellen acuity + + racy the Logmar chart should replace the Snellen chart as Reading vision + ++ the standard acuity test. Contrast sensitivity (CS) ++ + CS + Glare +++ + Reading Vision CS + 'Noise' + ++ Interferometry + ++ There is a need for a rigorous test of near vision. It is well Threshold displacement 0 ++ Correspondence to: J. R. Weatherill, Department of Ophthalmology, The symbols indicate the sensitivity of each test to optical degradation Bradford Royal Infirmary, Bradford, West Yorkshire BD9 6RJ, UK. and retinal function. Eye (1993) 7,26-28 VISUAL ACUITY ASSESSMENT 27 6 demonstrate visual handicap which is not necessarily apparent from the Snellen acuity. 5 GLARE AND CONTRAST SENSITIVITY If the patient is asked to view a contrast sensitivity or Snel­ len chart against a bright background the acuity drops 4 further in the presence of lens opacities. This accords with u I- " clinical experience that glare can be a major problem even C when the Snellen acuity is good. The converse of glare E 3 testing is the pinhole test in which a fine beam of light is 0< < guided through a clear part of the lens: because of the nar­ i rowness of the beam, refractive blur circles are at a mini­ 2 mum. Under these conditions some patients with dense opacities can see well, thus demonstrating the integrity of the macula. 'NOISE' CHARTS It is well known that contrast sensitivity is reduced in ret­ o cataract norms PSC cortical nuclear inal and neural disorders as well as by cataract, and in N.26 N.40 N.13 N.l0 N-3 order to improve the specificity of contrast sensitivity tests Fig. I. Minimum angle of resolution (M.A.R.)for both the cat­ a chart has been devised to differentiate between loss of aract and the normative group. The cataract group is further contrast sensitivity from lens opacities and loss of contrast subdivided into posterior subcapsular (PSC), cortical and sensitivity from retinal and neural disorders. The auditory nuclear types. Standard error bars are shown. system can recognise a tune or conversation against a aract patients is difficulty in recognising faces. In order to background of random noise. Similarly, the visual system do this low-frequency contrast sensitivity is needed to can identify meaningful signals against a random back­ a reveal the patterns of light and shade which correspond to ground. The hypothesis is that if patient is tested on a the facial features; patients who have lost low-frequency clean Pelli-Robson chart and on one splattered with contrast sensitivity but retain high-frequency contrast sen­ blotches ('background noise'), then the results should be sitivity perceive only the sharp boundaries at the edges of similar if the loss of contrast sensitivity is due to cataract major features. but will show a greater loss on the 'noisy' chart if the ret­ Using the Bristol questionnaire devised by Lowe, inal and neural systems are impaired. This test is at an Elliote has demonstrated a much closer correlation early stage of development and reproducible results are between a patient's perceived disability and loss of con­ not yet available. trast sensitivity than between perceived disability and 50 Logmar acuity. The questionnaire comprises 20 questions relating to hobbies, mobility, reading, television watching 45 and recognition of faces. The contrast sensitivity was -;:; measured on the Pelli-Robson chart. The patients were L. 40 " tested monocularly and binocularly and a glare test was c..i Q) included. A multivariate analysis showed that: � 35 Q ...J 1. 0 30 Snellen visual acuity did not correlate well with out­ :>: V1 door tasks but did correlate with reading difficulty. The IoU Ol visual acuity of the worse eye gave the closer correla­ :>: 25 f- tion. This is an example of binocular inhibition. f- Z IoU 20 2. Poor binocular contrast sensitivity correlated well with I: IoU u disability outdoors as well as with difficulty with near < 15 ...J vision tasks. Q, V1 10 Contrast sensitivity measurements are therefore a more ;:; reliable guide to the likely benefits of cataract surgery than 5 are Snellen acuity measurements. Even more important is the finding that the blurred image from the worse eye 0 cataract norms PSC cortical nuclear inhibits contrast sensitivity in the better eye.3 It follows N-26 N-40 N-13 N-l0 N=3 that during normal binocular viewing patients who have Fig. 2. Displacement threshold in seconds of arc for both the uniocular cataract are suffering loss of vision in their cataract and the normative group. The cataract group is further normal eye and should therefore be offered cataract sur­ subdivided into posterior subcapsular (PSC) , cortical and gery. The results of contrast sensitivity testing clearly nuclear types. Standard error bars are shown. 28 J. R. WEATHERILL Threshold Amplitude (sec.arc) similarly very small movements can be perceived. A dis­ -------- ------- 180,---- placement threshold is the determination of the smallest change of position of an object which gives rise to the sen­ sation of movement. Low-frequency oscillation of 40" can 120 be detected in an isolated luminous target, but if stationary reference lines are added to the field of view then dis­ placements of 10" can be detected. The oscillation is seen as a displacement from the reference bars and not as an 60 inherent movement. The advantage of this technique is that it is relatively resistant to image decay by opacities. Fig. 1 shows the difference in Logmar acuity between a group of cataract LI ___ o L ----�-------'--------"-- o 2.5 5.0 7.5 10.0 patients and normal controls. Fig. 2 shows that both Eccentricity (degrees) groups have similar displacement thresholds, that is the Fig. 3. The minimum displacement or threshold displacement sensitivity to movement detection is not impaired by mod­ of a target which can be detected at increasing degrees of eccen­ erate lens opacities. The test is quick and easy for the tricity from fixation.
Load more

Recommended publications
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • 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
    [Show full text]
  • Ophthalmology Abbreviations Alphabetical
    COMMON OPHTHALMOLOGY ABBREVIATIONS Listed as one of America’s Illinois Eye and Ear Infi rmary Best Hospitals for Ophthalmology UIC Department of Ophthalmology & Visual Sciences by U.S.News & World Report Commonly Used Ophthalmology Abbreviations Alphabetical A POCKET GUIDE FOR RESIDENTS Compiled by: Bryan Kim, MD COMMON OPHTHALMOLOGY ABBREVIATIONS A/C or AC anterior chamber Anterior chamber Dilators (red top); A1% atropine 1% education The Department of Ophthalmology accepts six residents Drops/Meds to its program each year, making it one of nation’s largest programs. We are anterior cortical changes/ ACC Lens: Diagnoses/findings also one of the most competitive with well over 600 applicants annually, of cataract whom 84 are granted interviews. Our selection standards are among the Glaucoma: Diagnoses/ highest. Our incoming residents graduated from prestigious medical schools ACG angle closure glaucoma including Brown, Northwestern, MIT, Cornell, University of Michigan, and findings University of Southern California. GPA’s are typically 4.0 and board scores anterior chamber intraocular ACIOL Lens are rarely lower than the 95th percentile. Most applicants have research lens experience. In recent years our residents have gone on to prestigious fellowships at UC Davis, University of Chicago, Northwestern, University amount of plus reading of Iowa, Oregon Health Sciences University, Bascom Palmer, Duke, UCSF, Add power (for bifocal/progres- Refraction Emory, Wilmer Eye Institute, and UCLA. Our tradition of excellence in sives) ophthalmologic education is reflected in the leadership positions held by anterior ischemic optic Nerve/Neuro: Diagno- AION our alumni, who serve as chairs of ophthalmology departments, the dean neuropathy ses/findings of a leading medical school, and the director of the National Eye Institute.
    [Show full text]
  • Visual Optics
    Visual Optics Jim Schwiegerling, PhD Ophthalmology & Optical Sciences University of Arizona Visual Optics - Introduction • In this course, the optical principals behind the workings of the eye and visual system will be explained. • Furthermore, descriptions of different devices used to measure the properties and functioning of the eye will be described. • Goals are a general understanding of how the visual system works and exposure to an array of different optical instrumentation. 1 What is Vision? • Three pieces are needed for a visual system – Eye needs to form an “Image”. Image is loosely defined because it can be severely degraded and still provide information. – Image needs to be converted to a neural signal and sent to the brain. – Brain needs to interpret and process the image. Analogous Vision System Feedback Video Computer Camera Analysis Display Conversion & Image To Signal Interpretation Formation 2 Engineering Analysis • Optics – Aberrations and raytracing are used to determine the optical properties of the eye. Note that the eye is non- rotationally symmetric, so analysis is more complex than systems normally discussed in lens design. Fourier theory can also be used to determine retinal image with the point spread function and optical transfer function. •Neural– Sampling occurs by the photoreceptors (both spatial and quantification), noise reduction, edge filtering, color separation and image compression all occur in this stage. •Brain– Motion analysis, pattern recognition, object recognition and other processing occur in the brain. Anatomy of the Eye Anterior Chamber –front portion of the eye Cornea –Clear membrane on the front of the eye. Aqueous – water-like fluid behind cornea. Iris – colored diaphragm that acts as the aperture stop of the eye.
    [Show full text]
  • Scleral Lenses in the Management of Keratoconus
    ARTICLE Scleral Lenses in the Management of Keratoconus Muriel M. Schornack, O.D., and Sanjay V. Patel, M.D. Management of patients with keratoconus consists primarily of Purpose: To describe the use of Jupiter scleral lenses (Medlens Innova- providing optical correction to maximize visual function. In very tions, Front Royal, VA; and Essilor Contact Lenses, Inc., Dallas, TX) in the management of keratoconus. mild or early disease, spectacle correction or standard hydrogel or Methods: We performed a single-center retrospective chart review of our silicone hydrogel lenses may provide adequate vision. However, initial 32 patients with keratoconus evaluated for scleral lens wear. All disease progression results in increasing ectasia, which gives rise patients were referred for scleral lens evaluation after exhausting other to complex optical aberrations. Rigid gas-permeable contact lenses nonsurgical options for visual correction. Diagnostic lenses were used in mask these aberrations by allowing a tear lens to form between the the initial fitting process. If adequate fit could not be achieved with contact lens and the irregular corneal surface. Zadnik et al. found standard lenses, custom lenses were designed in consultation with the that 65% of patients who enrolled in the Collaborative Longitudi- manufacturers’ specialists. The following measures were evaluated for nal Evaluation of Keratoconus study were wearing rigid gas- each patient: ability to tolerate and handle lenses, visual acuity with scleral permeable lenses in one or both eyes at the time of enrollment.4 lenses, number of lenses, and visits needed to complete the fitting process. Despite their optical benefit, corneal rigid gas-permeable lenses Results: Fifty-two eyes of 32 patients were evaluated for scleral lens may not be appropriate for all patients with keratoconus.
    [Show full text]
  • Contrast Sensitivity and Acuity Relationship in Strabismic and Anisometropic Amblyopia
    Br J Ophthalmol: first published as 10.1136/bjo.72.1.44 on 1 January 1988. Downloaded from British Journal of Ophthalmology, 1988, 72, 44-49 Contrast sensitivity and acuity relationship in strabismic and anisometropic amblyopia M ABRAHAMSSON AND J SJOSTRAND From the Department of Ophthalmology, University of Goteborg, Sahlgren's Hospital S-413 45 Goteborg, Sweden SUMMARY The contrast sensitivity function (CSF) and visual acuity were determined in children and adults with unilateral amblyopia due to strabismus or anisometropia with central fixation. The preschool children were examined repeatedly during occlusion treatment. All amblyopes had CSF deficits. The CSF was characterised by its peak value (the maximal sensitivity, Smax, and the spatial frequency at which Smax occurs, Frmax) calculated by a single peak least-square regression method. The two amblyopic groups showed discrepancies in relationship of both Smax and Frmax versus visual acuity both initially and during treatment. The strabismic cases had a more marked visual acuity deficit in relation to the contrast sensitivity losses, whereas these parameters are affected similarly in anisometropic amblyopes. The relationship between recovery of visual acuity and CSF during the initial month of occlusion treatment was of prognostic significance for the outcome of visual acuity improvement. copyright. Amblyopia is defined as an optically uncorrectable receives an input with deprived form and contour. loss of vision, usually monocular, without demon- There is no evidence that a strabismic eye receives a strable pathology in the posterior pole of the eye. blurred image, whereas several studies indicate that This condition develops in early childhood and it abnormal binocular interaction is present in http://bjo.bmj.com/ affects up to 5% of the population.
    [Show full text]
  • Home Visual Acuity Testing
    Home Visual Acuity Testing Vision testing is an important component of the eye evaluation. While office-based testing is most accurate, in-home testing can still provide helpful information for your doctor. The vision charts in this document may either be printed or viewed on a computer or tablet. We recommend printing the chart, if possible, instead of using a screen. Tape it to a wall in a well- lit space. Instructions 1. To test distance vision, adults should use the standard ETDRS eye chart (page 2). Children should use the HOTV chart and matching page (pages 3 and 4). 2. Please be sure that the chart is displayed at the correct size prior to testing. The circle on the chart should measure 1 inch, the size of a US quarter dollar coin. The orange lines at the bottom of the charts should each measure 86 mm, the size of the long edge of a standard credit card. If viewing on a digital screen, adjust the document zoom until the document is displayed in the correct dimensions. 3. If you wear glasses to see far away, wear them for the distance vision test. Stand exactly 5 feet from the eye chart when checking distance vision. 4. If you wear reading glasses or bifocals, wear them for the near vision test. Hold the near vision chart 14 inches from your face when checking near vision. 5. Test vision using one eye at a time. Cover the opposite eye using a Kleenex, large spoon, or palm of a hand. Watch carefully to avoid accidental peeking, especially in between fingers.
    [Show full text]
  • Congenital Or Acquired Color Vision Defect – If Acquired What Caused It?
    Congenital or Acquired Color Vision Defect – If Acquired What Caused it? Terrace L. Waggoner O.D. 3730 Tiger Point Blvd. Gulf Breeze, FL 32563 [email protected] Course Handout AOA 2017 Conference: I. Different types of congenital colorblindness. A. Approximately 8% of the population has a congenital color vision deficiency. B. Dichromate 1. Protanopia is a severe type of color vision deficiency caused by the complete absence of red retinal photoreceptors (L cone absent). 2. Deuteranopia is a type of color vision deficiency where the green photoreceptors are absent (M cone absent). 3. Tritanopia is a very rare color vision disturbance in which there are only two cone pigments present and a total absence of blue retinal receptors (S cone absent). It is related to chromosome 7. C. Anomalous Trichromate 1. Protanomaly is a mild color vision defect in which an altered spectral sensitivity of red retinal receptors (closer to green receptor response) results in poor red–green hue discrimination. 2. Deuteranomaly, caused by a similar shift in the green retinal receptors, is by far the most common type of color vision deficiency, mildly affecting red–green hue discrimination in 5% males. 3. Tritanomaly is a rare, hereditary color vision deficiency affecting blue–green and yellow–red/pink hue discrimination. D. Rates of color blindness 1. Dichromacy Males 2.4% Females .03% a. Protanopia (red deficient: L cone absent) Males 1.3% Females 0.02% b. Deuteranopia (green deficient: M cone absent) Males 1.2% Females 0.01 c. Tritanopia (blue deficient: S cone absent) Males 0.001% Females 0.03% 2.
    [Show full text]
  • 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.
    [Show full text]
  • Visual Impairment Care Needs of the Public Through Clinical Care, Research, and Education, All of Which Enhance the Quality of Life
    OPTOMETRY: OPTOMETRIC CLINICAL THE PRIMARY EYE CARE PROFESSION PRACTICE GUIDELINE Doctors of optometry (ODs) are the primary health care professionals for the eye. Optometrists examine, diagnose, treat, and manage diseases, injuries, and disorders of the visual system, the eye, and associated structures as well as identify related systemic conditions affecting the eye. 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. Approximately 37,000 full-time equivalent doctors of optometry practice in more than 7,0000 communities across the United States, serving as the sole primary eye care provider in more than 4,300 communities. Care of the Patient with The mission of the profession of optometry is to fulfill the vision and eye Visual Impairment care needs of the public through clinical care, research, and education, all of which enhance the quality of life. (Low Vision Rehabilitation) OPTOMETRIC CLINICAL PRACTICE GUIDELINE CARE OF THE PATIENT WITH VISUAL IMPAIRMENT (LOW VISION REHABILITATION) Reference Guide for Clinicians Prepared by the American Optometric Association Consensus Panel on Care of the Patient with Low Vision Kathleen Fraser Freeman, O.D., Principal Author Roy Gordon Cole, O.D. Eleanor E. Faye, M.D. Paul B. Freeman, O.D. Gregory L. Goodrich, Ph.D. Joan A. Stelmack, O.D. Reviewed by the AOA Clinical Guidelines Coordinating Committee: David A. Heath, O.D., Chair John F. Amos, O.D., M.S. Stephen C. Miller, O.D.
    [Show full text]
  • Mapping the Binocular Scotoma in Macular Degeneration
    Journal of Vision (2021) 21(3):9, 1–12 1 Mapping the binocular scotoma in macular degeneration Smith-Kettlewell Eye Research Institute, San Francisco, Cécile Vullings CA, USA Smith-Kettlewell Eye Research Institute, San Francisco, Preeti Verghese CA, USA When the scotoma is binocular in macular degeneration where cortical processes perceptually complete missing (MD), it often obscures objects of interest, causing information by extrapolating the background (Zur & individuals to miss information. To map the binocular Ullman, 2003), although this challenge has not been scotoma as precisely as current methods that map the addressed under binocular viewing and it is unclear monocular scotoma, we propose an iterative eye-tracker how the nature of the stimulus affects this phenomenon method. Study participants included nine individuals (Cohen, Lamarque, Saucet, Provent, Langram, & with MD and four age-matched controls. We measured LeGargasson, 2003). the extent of the monocular scotomata using a scanning The binocular scotoma results from an overlap of the laser ophthalmoscope/optical coherence tomography two monocular scotomata and determines functional (SLO/OCT). Then, we precisely mapped monocular and vision in the real world. The residual vision outside binocular scotomata with an eye tracker, while fixation the scotoma along with factors, such as where it is was monitored. Participants responded whenever they placed with respect to the eccentric fixation locus, detected briefly flashed dots, which were first presented on a coarse grid, and then at manually selected points to determines performance in tasks including eye-hand refine the shape and edges of the scotoma. Monocular coordination (e.g. Verghese, Tyson, Ghahghaei, & scotomata measured in the SLO and eye tracker are Fletcher, 2016), navigation (e.g.
    [Show full text]