In vivo Measurement of Corneal Stiffness and Intraocular Pressure to Enable Personalised Disease Management and Treatment

Eliasy, Ashkan ORCID: 0000-0002-4473-1900
(2021) In vivo Measurement of Corneal Stiffness and Intraocular Pressure to Enable Personalised Disease Management and Treatment. Doctor of Philosophy thesis, University of Liverpool.

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In ophthalmology, accurate measurement of intraocular pressure (IOP) and in vivo measurement of corneal material stiffness have been long-standing problems. Access to this information would transform the diagnosis and therapy of diseases and conditions such as glaucoma, refractive errors and keratoconus that are currently affecting over 50% of the world population. The aim of this study is to develop new methods for the accurate measurement of IOP and corneal material stiffness in vivo. To achieve this goal, a mathematical method was developed to analyse tomography data of keratoconic corneas, to estimate the area, height and location of the keratoconic cone. This information was utilised in the development of representative numerical models of the ocular globe. A large parametric study was then conducted, and with the aid of custom-built programming tools, high-performance computing and optimisation techniques, new methods were developed. These methods enabled the use of information obtained from a non-contact tonometry device to estimate biomechanically corrected IOP and corneal material stiffness. Methods developed in this study were validated on data collected from experimental tests as well as a large clinical database obtained from four continents. The results showed that the newly developed methods for measuring IOP are more accurate than those currently available in the market. IOP measurements were stable when compared in pre and post-surgical procedures such as refractive correction or corneal crosslinking. IOP values showed a weak/no correlation with geometrical or biomechanical parameters. Further methods for measuring corneal biomechanics in-vivo showed notable advancements compared to the existing method. Biomechanical values were weakly/not correlated with IOP and geometrical features while strongly correlated with age as an indication of changes in material stiffness. The experimental validation showed excellent agreement between the in-vivo measurements in comparison to ex-vivo findings. The outcome of this research will have an impact on the better diagnosis of glaucoma by eliminating misdiagnosis due to IOP measurement inaccuracies. Further, it enables personalised disease management and treatment through in-vivo measurement of corneal biomechanics that leads to optimisation of surgical procedures, most notably corneal crosslinking and refractive surgeries.

Item Type: Thesis (Doctor of Philosophy)
Divisions: Faculty of Science and Engineering > School of Engineering
Depositing User: Symplectic Admin
Date Deposited: 25 Jun 2021 10:07
Last Modified: 18 Jan 2023 22:34
DOI: 10.17638/03126717