THE ASSOCIATION BETWEEN FOURTH CRANIAL NERVE PALSY AND CONVERGENCE INSUFFICIENCY by Meghan C. Tice Submitted in partial fulfillment of the requirements for the degree of Master of Science at Dalhousie University Halifax, Nova Scotia September 2017 Copyright by Meghan C. Tice, 2017 TABLE OF CONTENTS LIST OF TABLES ........................................................................................................... v LIST OF FIGURES ........................................................................................................ vi ABSTRACT ................................................................................................................ viii LIST OF ABBREVIATIONS USED ................................................................................... ix ACKNOWLEDGEMENTS ............................................................................................... x CHAPTER 1: INTRODUCTION ....................................................................................... 1 1.1. Background ..................................................................................................... 1 1.2. Specific Disorders of Binocular Vision .............................................................. 2 1.2.1. Fourth Nerve Palsy (SOP) ................................................................................. 5 1.2.2. Convergence Insufficiency (CI) ...................................................................... 19 1.3. Purpose of the Study ..................................................................................... 26 1.4. Research Questions ....................................................................................... 26 CHAPTER 2: LITERATURE REVIEW .............................................................................. 28 2.1. Critical Analysis of Literature ......................................................................... 28 2.2. Clinical Findings of Intermittent Exotropia and Superior Oblique Palsy ........... 28 CHAPTER 3: METHODS ............................................................................................. 31 3.1. Study Design ................................................................................................. 31 3.1.1. General Study Design ..................................................................................... 31 3.1.2. Participants .................................................................................................... 31 3.1.3. Data Analysis .................................................................................................. 31 3.2. Recruitment .................................................................................................. 32 3.2.1. Study Population & Testing sites ................................................................... 32 3.2.2. Social / Cultural / Safety Considerations ....................................................... 32 3.2.3. Permissions .................................................................................................... 32 3.3. Ethics and Study Information ........................................................................ 32 3.4. Detailed Methodology .................................................................................. 33 ii 3.4.1. Testing Procedure .......................................................................................... 33 3.4.2. Recorded Data................................................................................................ 36 3.4.3. Research Team ............................................................................................... 36 3.4.4. Subject Study Duration .................................................................................. 36 3.5. Risk Analysis ................................................................................................. 37 3.5.1. Confidentiality & Anonymity.......................................................................... 37 3.5.2. Conflict of Interest ......................................................................................... 37 3.6. Statistical Tests ............................................................................................. 38 CHAPTER 4: RESULTS ................................................................................................ 40 4.1. Statistical Analysis ......................................................................................... 40 4.2. Primary Analysis............................................................................................ 40 4.2.1. Convergence Insufficiency Subjects ............................................................... 42 4.2.2. SOP Subjects ................................................................................................... 43 4.2.3. Data Analysis .................................................................................................. 45 4.3. Revised Analysis ............................................................................................ 49 4.3.1. Convergence Insufficiency Subjects ................................................................ 51 4.3.2. SOP Subjects ................................................................................................... 53 CHAPTER 5: DISCUSSION .......................................................................................... 60 5.1. Summary of Primary Analysis ........................................................................ 60 5.2. Summary of Revised Analysis ........................................................................ 63 5.3. Practical Implications for our Department ..................................................... 64 5.4. Potential Limitations ..................................................................................... 64 CHAPTER 6: CONCLUSIONS & FUTURE DIRECTIONS ................................................... 68 REFERENCES ............................................................................................................. 70 APPENDICES ............................................................................................................. 76 APPENDIX A – Site Locations ................................................................................. 76 APPENDIX B – Ethic Approval Nationwide Children’s Hospital ............................... 77 APPENDIX C – Ethic Approval Dalhousie University ............................................... 78 iii APPENDIX D – Subject information sheet .............................................................. 79 APPENDIX E – Statistics for Primary analysis ......................................................... 80 APPENDIX F – Cross Tabulation Interpretation Table ............................................. 86 APPENDIX G – Raw Data ....................................................................................... 87 iv LIST OF TABLES Table 1A. Strabismus classification.......................................................................... 3 Table 1B. Main clinical features of SOP.................................................................. 15 Table 4A. SOP characteristics versus presence of CI............................................... 46 v LIST OF FIGURES Figure 1A. Superior oblique pathway from the nerve to the orbit.............................. 7 Figure 1B. Superior oblique muscle passing through the superior orbital fissure...... 7 Figure 1C. Flowchart for vertical strabismus and types of SOP................................ 14 Figure 4A. Subject examination locations.................................................................. 41 Figure 4B. Examiner distribution............................................................................... 41 Figure 4C. Age distribution of all subjects................................................................ 42 Figure 4D. Age distribution of CI subjects................................................................ 43 Figure 4E. Age distribution of all SOP subjects....................................................... 44 Figure 4F. Age distribution of congenital SOP subjects.......................................... 44 Figure 4G. Age distribution of acquired SOP subjects............................................. 45 Figure 4H. Revised analysis - subject examination location.................................... 50 Figure 4I. Revised analysis - examiner distribution of recruitment........................ 50 Figure 4J. Revised analysis - age distribution of subjects....................................... 51 Figure 4K. Revised analysis - examination location for CI subjects........................ 52 Figure 4L. Revised analysis - examiner distribution of recruitment for CI subjects................................................................................................... 52 Figure 4M. Revised analysis - age distribution of CI subjects.................................. 53 Figure 4N. Revised analysis - examination location for SOP subjects..................... 54 Figure 4O. Revised analysis - examiner distribution of recruitment for SOP subjects.................................................................................................... 54 Figure 4P. Revised analysis - age distribution of SOP subjects............................... 55 Figure 4Q. Revised analysis - examination location for congenital SOP subjects... 56 Figure 4R. Revised analysis - examiner distribution of recruitment for congenital subjects...................................................................................56