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Age-related macular degeneration (AMD) is the leading cause of central visual impairment in the elderly. The exact pathophysiological mechanisms for AMD remain uncertain. Several studies suggest that choroidal abnormalities and alterations are critical in AMD progression. The transition from manual to automated segmentation and binarization techniques has resulted in accurate and precise measurements of different choroidal parameters. These qualitative and quantitative parameters, known as choroidal imaging biomarkers, have advanced from basic vertical subfoveal choroidal thickness to more intricate 3-dimensional choroidal reconstruction methods in the last decade. Therefore, a comprehensive evaluation of choroidal metrics may investigate valuable insights into AMD, potentially guiding the future development of customized therapeutic strategies and personalized patient care in AMD management. We describe the role of different choroidal biomarkers in evaluating patients with AMD and their contribution to management., Competing Interests: Declaration of Competing Interest We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. We confirm that the manuscript has been read and approved by all named authors and that there are no other people who satisfied the criteria for authorship but are not listed. We further confirm that the order of authors listed in the manuscript has been approved by all of us. We further confirm that any aspect of the work covered in this manuscript that has involved has been conducted with the ethical approval of all relevant. We understand that the Corresponding Author (Jay Chhablani MD) is the sole contact for the Editorial process (including Editorial Manager and direct communications with the office). He is responsible for communicating with the other authors about progress, submissions of revisions and final approval of proofs. We confirm that we have provided a current, correct email address which is accessible by the Corresponding Author., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The choroid is the vascular coat of the eye, and its role has been studied in multiple chorioretinal disorders. Recent advancements in choroidal imaging techniques, including enhanced depth imaging optical coherence tomography, swept source optical coherence tomography, en face optical coherence tomography, and optical coherence tomography angiography have facilitated an in-depth analysis of the choroid. The gradual shift from manual to automated segmentation and binarization methods have led to precise and reproducible measurements of choroidal parameters. These qualitative and quantitative parameters, called choroidal imaging biomarkers, have evolved over the past decade from a simple linear subfoveal choroidal thickness to more complex 3D choroidal reconstruction, thus widening the spectrum encompassing multiple parameters. These biomarkers have provided a better understanding of the pathogenesis, are helpful in diagnostic dilemmas, and, in the future may also help to devise treatment options. The lack of normative data, absence of standardized parameters, and limitations of the imaging techniques, however, have led to ambiguity and difficulty in the interpretation of these variables. We attempt to address these lacunae in the literature and provide a basic understanding of the choroid in both health and disease using these choroidal biomarkers., (Copyright © 2018 Elsevier Inc. All rights reserved.)

A variety of vision ailments are indicated by anomalies in the choroid layer of the posterior visual section. Consequently, choroidal thickness and volume measurements, usually performed by experts based on optical coherence tomography (OCT) images, have assumed diagnostic significance. Now, to save precious expert time, it has become imperative to develop automated methods. To this end, one requires choroid outer boundary (COB) detection as a crucial step, where difficulty arises as the COB divides the choroidal granularity and the scleral uniformity only notionally, without marked brightness variation. In this backdrop, we measure the structural dissimilarity between choroid and sclera by structural similarity (SSIM) index, and hence estimate the COB by thresholding. Subsequently, smooth COB estimates, mimicking manual delineation, are obtained using tensor voting. On five datasets, each consisting of 97 adult OCT B-scans, automated and manual segmentation results agree visually. We also demonstrate close statistical match (greater than 99.6% correlation) between choroidal thickness distributions obtained algorithmically and manually. Further, quantitative superiority of our method is established over existing results by respective factors of 27.67% and 76.04% in two quotient measures defined relative to observer repeatability. Finally, automated choroidal volume estimation, being attempted for the first time, also yields results in close agreement with that of manual methods., (Copyright © 2015 Elsevier Ltd. All rights reserved.)