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Measuring and Modelling Forward Light Scattering in the Human Eye

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Measuring and Modelling Forward Light Scattering in the Human Eye MEASURING AND MODELLING FORWARD LIGHT SCATTERING IN THE HUMAN EYE A thesis submitted to The University of Manchester, for the degree of Doctor of Philosophy, in the Faculty of Life Sciences. 2015 Pablo Benito López Optometry THESIS CONTENT THESIS CONTENT ...................................................................................................................... 2 LIST OF FIGURES ....................................................................................................................... 5 LIST OF TABLES ........................................................................................................................ 10 LIST OF EQUATIONS ............................................................................................................... 11 ABBREVIATIONS LIST ........................................................................................................... 12 ABSTRACT ................................................................................................................................... 13 DECLARATION .......................................................................................................................... 14 THESIS FORMAT ....................................................................................................................... 14 COPYRIGHT STATEMENT .................................................................................................... 15 ACKNOWLEDGEMENTS ....................................................................................................... 16 1. INTRODUCTION ................................................................................................................ 17 1.1 OVERVIEW .......................................................................................................... 17 1.2 WHAT IS INTRAOCULAR LIGHT SCATTER? ................................................ 18 1.3 INTRAOCULAR SCATTER, GLARE AND STRAYLIGHT.............................. 22 1.4 INTRAOCULAR SCATTER AND CONTRAST SENSITIVITY ....................... 23 1.5 SCATTER AND POINT SPREAD FUNCTION .................................................. 24 1.6 SOURCES OF SCATTER ..................................................................................... 26 1.6.1 CORNEA ....................................................................................................... 27 1.6.2 CRYSTALLINE LENS .................................................................................. 29 1.6.3 IRIS, SCLERA AND UVEAL TRACT ......................................................... 32 1.6.4 RETINA ......................................................................................................... 33 1.7 FACTORS AFFECTING INTRAOCULAR LIGHT SCATTER .......................... 33 1.7.1 PHYSIOLOGICAL ........................................................................................ 34 1.7.2 PATHOLOGICAL .......................................................................................... 34 1.7.3 OPTICAL ....................................................................................................... 39 1.8 METHODS TO MEASURE INTRAOCULAR LIGHT SCATTER .................... 40 1.8.1 METHODS BASED ON THE MEASUREMENT OF CONTRAST SENTITIVITY .............................................................................................................. 40 1.8.2 METHODS BASED ON THE EQUIVALENT LUMINANCE TECHNIQUE ……………………………………………………………………………...42 1.8.3 ESTIMATIONS OF FORWARD LIGHT SCATTER FROM BACKWARD LIGHT SCATTER ........................................................................................................ 49 2 1.8.4 METHODS BASED ON THE DOUBLE-PASS TECHNIQUE ................... 49 1.9 RATIONALE ......................................................................................................... 57 2. COMPARISON OF THE COMPENSATION COMPARISON METHOD AND THE DIRECT COMPENSATION METHOD FOR STRAYLIGHT MEASUREMENT ........................................................................................................................ 60 2.1 CONTRIBUTIONS .................................................................................................... 60 2.2 PUBLISHING OF THE PAPER ................................................................................ 60 2.3 PRESENTATION AT CONFERENCE ...................................................................... 60 2.4 ABSTRACT ............................................................................................................... 61 2.5 INTRODUCTION ...................................................................................................... 62 2.6 METHODS ................................................................................................................. 63 2.7 RESULTS ................................................................................................................... 67 2.8 DISCUSSION ............................................................................................................ 75 3. COMPARISON OF FORWARD LIGHT SCATTER ESTIMATIONS USING HARTMANN - SHACK SPOT PATTERNS AND C-QUANT .......................................... 78 3.1 CONTRIBUTIONS .................................................................................................... 78 3.2 PUBLISHING OF THE PAPER ................................................................................ 78 3.3 PRESENTATION AT CONFERENCE ...................................................................... 78 3.4 ABSTRACT ............................................................................................................... 79 3.5 INTRODUCTION ...................................................................................................... 80 3.6 METHODS ................................................................................................................. 82 3.7 RESULTS ................................................................................................................... 91 3.8 DISCUSSION ............................................................................................................ 93 4. FORWARD AND BACKWARD LIGHT SCATTER MEASUREMENTS IN THE HUMAN EYE................................................................................................................................ 97 4.1 CONTRIBUTIONS .................................................................................................... 97 4.2 PUBLISHING OF THE PAPER ................................................................................ 97 4.3 PRESENTATION AT CONFERENCE ...................................................................... 97 4.4 ABSTRACT ............................................................................................................... 98 4.5 INTRODUCTION ...................................................................................................... 98 4.6 METHODS ............................................................................................................... 101 4.7 RESULTS ................................................................................................................. 107 4.8 DISCUSSION .......................................................................................................... 110 5. INSTRUMENT AND COMPUTERIZED BASED MODEL FOR THE OBJECTIVE MEASUREMENT OF FORWARD LIGHT SCATTER ......................... 115 3 5.1 CONTRIBUTIONS .................................................................................................. 115 5.2 PUBLISHING OF THE PAPER .............................................................................. 115 5.3 PRESENTATION AT CONFERENCE .................................................................... 115 5.4 ABSTRACT ............................................................................................................. 116 5.5 INTRODUCTION .................................................................................................... 117 5.6 REVIEW OF FLS MEASURING AND MODELING ............................................ 118 5.6.1 MODELLING FLS ............................................................................................ 118 5.6.2 MEASURING FLS ............................................................................................ 120 5.7 METHODS ............................................................................................................... 122 5.7.1 EXPERIMENTAL SET-UP USED FOR EXPERIMENT 1 AND 2 ................. 123 5.7.2 FIRST EXPERIMENT: VALIDATION OF THE PROTOTYPE WITH CUSTOMISED LENSES AND ZEMAX MODEL ................................................... 126 5.7.3 SECOND EXPERIMENT: RESULTS FROM PARTICIPANTS, COMPARISON RESULTS PROTOTYPE / C-QUANT AND PROTOTYPE / ZEMAX SCATTER EYE MODEL ............................................................................................................. 128 5.8 RESULTS ................................................................................................................. 133 5.8.1 FIRST EXPERIMENT: VALIDATION OF THE PROTOTYPE WITH CUSTOMISED LENSES AND ZEMAX MODEL ................................................... 133 5.8.2 SECOND EXPERIMENT: RESULTS FROM PARTICIPANTS, COMPARISON RESULTS PROTOTYPE / C-QUANT AND PROTOTYPE / ZEMAX SCATTER EYE MODEL ............................................................................................................. 136 5.9 DISCUSSION .........................................................................................................
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