Head-Mounted Displays and Dynamic Text Presentation to Aid Reading in Macular Disease
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HEAD-MOUNTED DISPLAYS AND DYNAMIC TEXT PRESENTATION TO AID READING IN MACULAR DISEASE Howard Farnoush Freemantle Moshtael-Oskui Submitted for the degree of Doctor of Engineering Heriot-Watt University School of Engineering & Physical Sciences January 2017 The copyright in this thesis is owned by the author. Any quotation from the thesis or use of any of the information contained in it must acknowledge this thesis as the source of the quotation or information. ABSTRACT The majority of individuals living with significant sight loss have residual vision which can be enhanced using low vision aids. Smart glasses and smartphone-based headsets, both increasing in prevalence, are proposed as a low vision aid platform. Three novel tests for measuring the visibility of displays to partially sighted users are described, along with a questionnaire for assessing subjective preference. Most individuals tested, save those with the weakest vision, were able to see and read from both a smart glasses screen and a smartphone screen mounted in a headset. The scheme for biomimetic scrolling, a text presentation strategy which translates natural eye movement into text movement, is described. It is found to enable the normally sighted to read at a rate five times that of continuous scrolling and is faster than rapid serial visual presentation for individuals with macular disease. With text presentation on the smart glasses optimised to the user, individuals with macular disease read on average 65% faster than when using their habitual optical aid. It is concluded that this aid demonstrates clear benefit over the commonly used devices and is thus recommended for further development towards widespread availability. ACKNOWLEDGMENTS Primary thanks go to my supervisors, Ian Underwood and Bal Dhillon, for four years of support and guidance. Thanks also to Jenny Roe for initially taking up the mantel of supervisor. My gratitude goes to the funders, Edinburgh & Lothians Health Foundation and the Engineering & Physical Sciences Research Council, and to the Heriot-Watt University for taking me on. The next round of gratitude goes to my collaborators: First it was Peter Aspinall for assistance in getting started; and Tariq Aslam for the review paper and EURETINA Conference; then it was Lana Fu for the first patient trial; then Antje Nuthmann for biomimetic scrolling; and finally Cirta Tooth for the second patient trial. Each one of you went out of your way to help me, and your kindness is warmly appreciated. I have been very fortunate to receive the generous assistance of the following: Chi Can and Javid Khan of Holoxica for lending me your stuff and experience; Niall Strang and Lynne Watson for the consultation on jitter; Ian Murray for the tips on perimetry; Stephen Hicks for the tips on smart glasses; Pietro Zambelli for the help with Python; the Macular Society, Jean Pringle and Cleodie MacKinnon in particular, for the opportunity to meet the AMD; the RNIB, for leading the way; Ellie Brown for help with the trials; Josie Grant for tips on eccentric viewing; Anita Simmers, Richard Watson and Ryan Gibson for the GCU connection that helped get me going in the beginning; Malath Abbas and Kenneth Scott-Brown for the Dundee connection; Ian Hodson for the chats on accessibility; Elodie Draperi for keeping me in the smart glasses loop; Wolfgang Radner for your sentences; Douglas Young and Alex Bailey for help with ethics; to the dynamic trio Linda Bruce, Alison Low and Colette Bush; to the SMC for welcoming this long term visitor; to my fellow research engineers for some fun times. My sincere thanks go to each of you. Final thanks go to my wife, my family and friends for everything else. If I have forgotten you, you are included under the category of friends. ACADEMIC REGISTRY Research Thesis Submission Name: School: Version: (i.e. First, Degree Sought: Resubmission, Final) Declaration In accordance with the appropriate regulations I hereby submit my thesis and I declare that: 1) the thesis embodies the results of my own work and has been composed by myself 2) where appropriate, I have made acknowledgement of the work of others and have made reference to work carried out in collaboration with other persons 3) the thesis is the correct version of the thesis for submission and is the same version as any electronic versions submitted*. 4) my thesis for the award referred to, deposited in the Heriot-Watt University Library, should be made available for loan or photocopying and be available via the Institutional Repository, subject to such conditions as the Librarian may require 5) I understand that as a student of the University I am required to abide by the Regulations of the University and to conform to its discipline. 6) I confirm that the thesis has been verified against plagiarism via an approved plagiarism detection application e.g. Turnitin. * Please note that it is the responsibility of the candidate to ensure that the correct version of the thesis is submitted. Signature of Date: Candidate: Submission Submitted By (name in capitals): Signature of Individual Submitting: Date Submitted: For Completion in the Student Service Centre (SSC) Received in the SSC by (name in capitals): Method of Submission (Handed in to SSC; posted through internal/external mail): E-thesis Submitted (mandatory for final theses) Signature: Date: CONTENTS 1. CHAPTER 1: Introduction 1 1.1 Introduction 1 1.2 Thesis structure 2 1.3 Low vision 4 1.3.1 The human eye 4 1.3.2 Performance measures of vision 8 1.3.3 Common causes of low vision 10 1.3.4 Reading requirements for normal and low vision 11 1.4 Head-mounted displays in low vision aids 13 1.4.1 Low vision aids 13 1.4.2 Head-mounted displays 15 1.4.3 A review of head-mounted displays in low vision aids 15 1.5 Conclusion 20 1.6 References 21 2. CHAPTER 2: Review of image processing for the visually 30 impaired 2.1 Introduction 30 2.2 Methods 31 2.3 Results 32 2.3.1 Contrast enhancement 39 2.3.2 Spatial frequencies 39 2.3.3 Edge and contour enhancement 41 2.3.4 Background attenuation and scene simplification 42 2.3.5 Remapping and retargeting 43 2.3.6 Jitter 44 2.4 Discussion 45 2.4.1 Image distortion levels 45 2.4.2 Experimental design 45 2.4.3 Methods of evaluation 46 2.5 Conclusion 48 i 2.6 References 49 3. CHAPTER 3: Evaluation of Head-Mounted Displays for 55 Macular Degeneration 3.1 Introduction 55 3.2 Patient study methods 57 3.2.1 Participants 57 3.2.2 Ethical approval 57 3.2.3 Apparatus 58 3.2.4 Procedure 58 3.3 Head-mounted displays 60 3.3.1 Introduction 60 3.3.2 Smart glasses 61 3.3.3 Smartphone headset 62 3.4 Contrast visibility indicator 63 3.4.1 Introduction 63 3.4.2 Contrast Visibility Indicator 63 3.4.3 Algorithm 64 3.4.4 Graphical User Interface and control 70 3.4.5 Patient trial results 72 3.5 Extent of visibility 74 3.5.1 Introduction 74 3.5.2 Graphical User Interface 74 3.5.3 Algorithm 75 3.5.4 Patient trial results 78 3.6 Reading performance 82 3.6.1 Introduction 82 3.6.2 Visual acuity and reading acuity 82 3.6.3 Reading test on HMD 84 3.6.4 Patient trial results 87 3.7 Questionnaire 89 3.7.1 Introduction 89 3.7.2 Questionnaire design 89 ii 3.7.3 Patient trial results 90 3.8 Discussion 93 3.8.1 Visibility of screens 93 3.8.2 Electronic display compared to paper 93 3.8.3 Smart glasses compared to smartphone headset 95 3.8.4 Screen visibility tests 95 3.9 Conclusion 97 3.10 References 98 4. CHAPTER 4: Biomimetic or Saccadic Scrolling: Speed 100 Reading Strategy Based on Natural Eye Movements 4.1 Introduction 100 4.1.1 Introduction 100 4.1.2 Eye movements whilst reading 101 4.1.3 Presentation of text 102 4.1.4 Text presentation for the visually impaired 104 4.2 Eye movement corpus 106 4.2.1 Introduction 106 4.2.2 Materials and design 106 4.2.3 Participants 106 4.2.4 Apparatus 106 4.2.5 Procedure 106 4.2.6 Analysis 107 4.3 Reverse engineering individual gaze movements 108 4.3.1 Introduction 108 4.3.2 Reading eye movements 108 4.3.3 Reverse engineered eye movements 110 4.4 Parameters of biomimetic scrolling 114 4.4.1 Introduction 114 4.4.2 Pause duration 114 4.4.3 Number of pauses per word 116 4.4.4 Viewing position 118 4.4.5 Step duration 119 iii 4.4.6 Speed 119 4.5 Reading speed study 120 4.5.1 Introduction 120 4.5.2 Method 120 4.5.3 Results 123 4.6 Discussion 125 4.7 Conclusion 127 4.8 References 128 5. CHAPTER 5: Smart glasses and dynamic text presentation as 133 a novel reading aid for age-related macular degeneration 5.1 Introduction 133 5.2 Design of experiment 135 5.2.1 Participants 135 5.2.2 Ethical approval 136 5.2.3 Procedure 137 5.3 Text presentation app 139 5.3.1 Functioning and graphical user interface 139 5.3.2 Text control 141 5.3.3 Text input 142 5.4 Text presentation 144 5.4.1 Introduction 144 5.4.2 Biomimetic scrolling settings 145 5.4.3 Text settings 147 5.4.4 Methods 148 5.4.5 Results 149 5.4.6 Questionnaire 152 5.5 Jitter 154 5.5.1 Introduction 154 5.5.2 Implementation 154 5.5.3 Results 155 5.6 Stereoscopic display and laptop display 157 5.6.1 Introduction 157 iv 5.6.2 Implementation 157 5.6.3 Results 158 5.7 Discussion 161 5.7.1 Reading aid 161 5.7.2 Biomimetic scrolling 162 5.7.3 Jitter and peripheral word recognition 163 5.7.4 Fixation target 164 5.8 Conclusion 165 5.9 References 166 6.