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Danilo A. Jesus, D Robert Iskander; Assessment of corneal properties using Optical Coherence Tomography Speckle: A pilot study. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3375.
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© ARVO (1962-2015); The Authors (2016-present)
To explore the potential of Optical Coherence Tomography (OCT) speckle to assess biomechanical properties of cornea and to track their changes.
Several statistical models were used to fit the corneal backscatter OCT data. Parameters of competing models were calculated using maximum likelihood estimation and the best model was selected based on the goodness of fit. The influence of choosing different regions of interest was also taken into account. The applicability of the best model was tested analyzing corneal speckle statistics of subjects with different ages. In addition, variation of the corneal backscattering on subjects wearing contact lenses was tracked.
Generalized Gamma Distribution has proven so far, to be the best model to fit the OCT corneal speckle. Its scaling and two shape parameters have shown to be sensitive to the variation of corneal backscattering properties. Differences among people with different ages were observed, showing the possibility to access corneal age-related changes using OCT corneal envelope statistics. Similar results were obtained for subjects wearing contact lenses showing that corneal backscattering statistics can also be used to track diurnal changes of corneal biomechanical properties.
This study shows that Generalized Gamma distribution can be used to fit the corneal speckle and has a great potential to be a helpful complement to evaluate the structure and elastic properties of the cornea in-vivo.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
(a) OCT image of the cornea where the alternated red and green rectangles denote different regions of interest and (b) their respective probability density functions using Generalized Gamma distribution. (c) Corneal OCT image of a subject wearing a contact lens where the region of interest is denoted by the red line and (d) the corresponding envelope of the speckle data and its fit using Generalized Gamma, Gamma, Rayleigh and Nakagami distributions.
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