Publication Date

2019-08-06

Availability

Embargoed

Embargo Period

2021-08-05

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Biomedical Engineering (Engineering)

Date of Defense

2019-07-01

First Committee Member

Fabrice Manns

Second Committee Member

Jean-Marie Parel

Third Committee Member

Arthur Ho

Fourth Committee Member

Nöel Ziebarth

Fifth Committee Member

Weizhao Zhao

Sixth Committee Member

Giovanni Gregori

Abstract

Vision is worsening on a global scale. Myopia, a visual condition where distant objects appear blurry, is increasing in prevalence at an alarming rate. This condition typically starts during childhood and progressively worsens, potentially leading to more severe visual conditions if left unchecked. Currently, the best treatment method to slow myopic progression is heavily debated as the etiology of myopia is not fully understood. The development of effective long-term solutions require a better understanding of how vision changes with age. The cornea and lens, the length of the human eye, and the surrounding ocular media dictate visual quality. Extensive studies have been executed on the cornea and length of the eye but very limited information is currently available about the shape and optical properties of the lens. The position and properties of the lens make it difficult to measure accurately. As a result, current models of the lens are limit our ability to predict how optics of the eye may contribute to the development of myopia. One barrier impeding more accurate models of the lens is the lack of experimental data needed for validation of the theoretical models developed. Despite the advent of more precise imaging techniques, there is a severe lack of robust experimental data on lens shape and optical properties. This dissertation addresses the information gap by developing computational tools that process data acquired by optical systems to determine both the shape and optical properties of the lens. A computational algorithm was developed to characterize the power and spherical aberration of in-vitro lenses measured using a laser ray tracing aberrometer. Age-related changes in power and spherical aberration were characterized in 73 in-vitro lenses ranging between 0.25 and 56 years. Results suggest a bi-phasic trend in age-related changes in spherical aberration that may have implications for the development of myopia. Additionally, a novel automated algorithm was developed to determine the shape of ocular surfaces from two-dimensional OCT images acquired in-vivo. Using the novel algorithm, dynamic changes in lens shape during accommodation were quantified for the first time. Age-related changes in in-vivo lens shape were also quantified in a pilot study.

Keywords

imaging; oct; optical coherence tomography; automated; lrt; computation

Available for download on Thursday, August 05, 2021

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