Conference Papers

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Author: search.filters.author.Lakshminarayanan, V.

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    Optic disc segmentation using circular hough transform and curve fitting
    (Institute of Electrical and Electronics Engineers Inc., 2015) Gopalakrishnan, A.; Almazroa, A.; Raahemifar, K.; Lakshminarayanan, V.
    We present a technique to segment the optic disc (OD) boundary from a color retinal fundus image. The technique used involves the extraction and removal of blood vessels using a top hat transform and an inpainting process. Then, a circular Hough transform is applied to the detected edges to obtain a coarse boundary of the OD and following which probable points of the optic disc are fed to a curve fitting algorithm which uses a higher order polynomial to draw the final boundary of the optic disc. The optic disc segmentation is a crucial part in estimating the CDR (Cup-to-disc ratio) which can be used as an early indicator of glaucoma and for following the progression/remission of the disease. © 2015 IEEE.
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    Development and validation of a novel automated method for quantification of choroidal thickness in age-related macular degeneration
    (SPIE, 2021) Smitha, A.; Jidesh, P.; Janarthanam, J.; Lakshminarayanan, V.
    Age-related Macular Degeneration (AMD) is a progressive, irreversible retinal disorder, and one of the leading causes of severe visual impairment or even blindness in the elderly population. The choroid plays a vital role in the pathophysiology of AMD. It is known that abnormal choroidal blood flow leads to retinal photoreceptor dysfunction and eventual death. We propose a new automated algorithm that can be used to quantify choroidal thickness (CT) from Optical Coherence Tomography (OCT) images of the retina. This thickness evaluation procedure includes image contrast enhancement, localization around the fovea centralis, segmentation of Retinal Pigment Epithelium (RPE) and choroidal layer, followed by CT measurement at multiple locations in the sub-foveal region at intervals of 0.5 mm on both nasal and temporal sides up to a distance of 1 mm from the center of the foveal pit. The horizontal radial scan OCT images (Cirrus 5000, Carl Zeiss Meditec Inc., Dublin, CA) of both healthy and AMD patients were used to measure the CT using the new algorithm. The statistical tests convey that the CT of AMD patients is relatively smaller than the normal condition. Furthermore, t-Test conducted between the proposed approach and clinical approach of extracting CT measurements confirm that the proposed method is in good agreement with the clinical measurements. On an average, the thickness of the choroid is found to be 0.32 ± 0.10 mm for the normal category and 0.21 ± 0.06 mm for the AMD category, in the central sub-foveal region, as obtained from the proposed automatic CT measurement method. The clinical significance and the results of automated choroid extraction are discussed in this paper. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.