Doctor of Philosophy (PHD)
Biomedical Engineering (Engineering)
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The ability of the crystalline lens to change shape and bring near objects into focus is known as accommodation. Over time, the deformability of the lens decreases, deteriorating near visual function. This condition is known as presbyopia. There are many ways in which presbyopia correction is addressed, but currently there does not exist a method capable of restoring a dynamic visual range. In order to better understand the accommodative process and evaluate future corrective approaches, we require a system capable of dynamically acquiring refraction and biometric information. The goal of this work was to design, develop, and test a system that is capable of measuring dynamically the optical and physical changes that occur in the eye during stimulated accommodation. The system consists of: a high dynamic range Shack-Hartmann based autorefractor, an extended-depth spectral domain optical coherence tomography (SD-OCT) system for anterior segment imaging, a 1300 nm SD-OCT system for trans-scleral ciliary body imaging, and a dual channel modified Badal optometer for the stimulation of accommodation. This involved the development of optomechanical systems, software design for system integration, and the design of experiments to test system modules. A method to calculate lens power from OCT biometry, corneal topography, and refraction was devised to correlate change in lens thickness to lens power during accommodation. The results acquired during human subjects testing demonstrate proof of concept.
Accommodation; Ophthalmology; Optical Coherence Tomography; Ocular Aberrometry
Hernandez, Victor M., "Simultaneous Dynamic Optical Refraction and Biometry of the Human Accommodative Response" (2015). Open Access Dissertations. 1562.
Available for download on Thursday, December 21, 2017