Bifocal Lenses in Nearsighted Kids (BLINK) Study A Thesis Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Katherine Margaret Bickle, B.S. Graduate Program in Vision Science. The Ohio State University 2013 Thesis Committee: Dr. Jeffrey J. Walline, Advisor Prof. Lynn Mitchell Dr. Kathrine Osborn Lorenz Copyright by Katherine Margaret Bickle, B.S. 2013 Abstract Myopia control has become a widely investigated topic, as the prevalence of myopia in several areas of the world has been increasing over the past few decades. Center distance soft bifocal and orthokeratology contact lenses are the two most promising treatment methods for myopia control that are currently being investigated. As soft bifocal contact lenses are available in different add powers, the eye care practitioner fitting a child in this lens modality must pick an appropriate add power. There is speculation that increased peripheral myopic defocus results in more myopia control, so higher add powers may lead to a larger treatment effect. Currently, there have been no studies performed that evaluate subjectively and objectively a child’s visual performance with different add power soft bifocal contact lenses to determine a maximum add power that a child may tolerate. In this study, subjects were randomly assigned to wear Proclear or Proclear Multifocal “D” with +2.00 D add, +3.00 D add, or +4.00 D add contact lenses for one week each. Objective vision assessments showed statistically significant differences between the lenses for high contrast distance visual acuity for the right eye (Friedman’s test, p = 0.02), binocular low contrast distance visual acuity (Friedman’s test, p < 0.001), and binocular contrast sensitivity (Friedman’s test, p < 0.001). For high contrast distance visual acuity of the right eye, vision was worse for the single vision lens than the ii strongest add power. For binocular low contrast distance visual acuity and binocular contrast sensitivity, the differences varied among the add powers. Subjective vision assessments showed statistically significant differences between the lenses for glare/starbursts, ghost images, change of fixation distance, and overall vision (p < 0.05 for all). In general, subjective reports were worse for +3.00 D and +4.00 D add powers than for single vision lenses. There were few differences between add powers. Eye care practitioners should educate their patients on the benefits and potential drawbacks of soft multifocal contact lenses as a treatment method for myopia control. Soft bifocal contact lenses may reduce myopia progression, but the strongest add powers reduce objective measurements of vision, especially low contrast visual acuity and contrast sensitivity. Children may also notice more glare/starbursts, ghost images, difficulty changing fixation distance, and decrements in overall vision when wearing the strongest add powers. Results from this study indicate that the highest add powers may not be the best option for myopia control because they affect both objective and subjective vision in children. iii Dedication This document is dedicated to my family. iv Acknowledgments Thank you, Dr. Walline, for your support, wisdom, and advice throughout the past two years. I admire your enthusiasm, and I have learned so much by working with you that I could not have gained in another setting. The passion I have developed for working with children is largely because of you. You have always been so encouraging, and I am so fortunate to have had you as my advisor. Thank you, Professor Mitchell, for your expertise and desire to teach. Your positive attitude has been very encouraging throughout this process. I am very appreciative of your willingness to sit on my committee and the time you have spent assisting me. Thank you, Dr. Osborn, for taking the time to sit on my committee. As a non- OSU faculty member, it shows your commitment to the program and me by taking on this role, and I appreciate your support. Thank you, Kevin, for your patience and encouragement throughout my optometric and graduate education. Thank you to my parents and Kenneth for your guidance, reassurance, and knowledge. Your continual encouragement has inspired me to become a better person every day. For that, I will always be appreciative of everything you have done for me. v Vita June 2004 .......................................................Granville High School 2008................................................................B.S. Molecular Genetics, The Ohio State University 2009 - present .................................................Optometry Student, The Ohio State University Publications Nichols JJ, Bickle KM, Zink RC, Schiewe MD, Haque RM, Nichols KK. Safety and efficacy of topical azithromycin ophthalmic solution 1.0% in the treatment of contact lens-related dry eye. Eye & Contact Lens 2012;38:73-9. Armen TA, Vandse R, Crestanello JA, Bickle KM, and Nathan NS. Mechanisms of valve competency after mitral valve annuloplasty for ischaemic mitral regurgitation using the Geoform ring: insights from three-dimensional echocardiography. European Journal of Echocardiography 2009;10:74-81. Armen TA, Vandse, R, Bickle K, Nathan N. Three-dimensional echocardiographic evaluation of an incidental quadricuspid aortic valve. European Journal of Echocardiography 2008;9:318-320. Sai-Sudhakar CB, Vandse R, Armen TA, Bickle KM, and Nathan NS. Efficacy of chordal cutting in alleviating ischemic mitral regurgitation: Insights from 3-D Echocardiography. Journal of Cardiothoracic Surgery 2007;2:39. vi Fields of Study Major Field: Vision Science vii Table of Contents Abstract ............................................................................................................................... ii Dedication .......................................................................................................................... iv Acknowledgments............................................................................................................... v Vita ..................................................................................................................................... vi List of Tables ..................................................................................................................... xi List of Figures .................................................................................................................. xiii Chapter: 1: Introduction .................................................................................................................... 1 1.1 Myopia ...................................................................................................................... 1 1.1.1 Prevalence .......................................................................................................... 1 1.1.2 Public Health ...................................................................................................... 4 1.2 Pediatric Contact Lenses ........................................................................................... 5 1.2.1 Soft Contact Lenses ........................................................................................... 5 1.2.2 Gas Permeable Contact Lenses .......................................................................... 5 1.2.3 Corneal Refractive Therapy (CRT) ................................................................... 6 1.2.4 Comparison to Teenagers .................................................................................. 9 1.2.5 Benefits of Contact Lenses .............................................................................. 11 1.3 Myopia Control ....................................................................................................... 12 viii 1.3.1 Bifocal Spectacles ............................................................................................ 13 1.3.2 Undercorrection ............................................................................................... 15 1.3.3 Atropine ........................................................................................................... 16 1.3.4 Pirenzepine ....................................................................................................... 18 1.3.5 Corneal Refractive Therapy ............................................................................. 20 1.3.6 Gas Permeable Contact Lenses ........................................................................ 24 1.3.7 Soft Bifocal Contact Lenses ............................................................................. 25 1.4 Purpose of Study ..................................................................................................... 28 2: Methods ....................................................................................................................... 30 2.1 IRB Approval .......................................................................................................... 30 2.2 Study Design ........................................................................................................... 31 2.2.1 Study Contact Lenses ....................................................................................... 31 2.3 Entry Criteria .......................................................................................................... 32 2.4 Recruitment Methods .............................................................................................