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Three-dimensional non-parametric method for limbus detection

PURPOSE: To present a novel non-parametric algorithm for detecting the position of the human eye limbus in three dimensions and a new dynamic method for measuring the full 360° visible iris boundary known as white-to-white distance along the eye horizontal line. METHODS: The study included 88 partic...

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Autores principales: Abass, Ahmed, Lopes, Bernardo T., Eliasy, Ashkan, Wu, Richard, Jones, Steve, Clamp, John, Ambrósio, Renato, Elsheikh, Ahmed
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6261009/
https://www.ncbi.nlm.nih.gov/pubmed/30475843
http://dx.doi.org/10.1371/journal.pone.0207710
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author Abass, Ahmed
Lopes, Bernardo T.
Eliasy, Ashkan
Wu, Richard
Jones, Steve
Clamp, John
Ambrósio, Renato
Elsheikh, Ahmed
author_facet Abass, Ahmed
Lopes, Bernardo T.
Eliasy, Ashkan
Wu, Richard
Jones, Steve
Clamp, John
Ambrósio, Renato
Elsheikh, Ahmed
author_sort Abass, Ahmed
collection PubMed
description PURPOSE: To present a novel non-parametric algorithm for detecting the position of the human eye limbus in three dimensions and a new dynamic method for measuring the full 360° visible iris boundary known as white-to-white distance along the eye horizontal line. METHODS: The study included 88 participants aged 23 to 65 years (37.7±9.7), 47 females and 41 males. Clinical characteristics, height data and the apex coordinates and 1024×1280 pixel digital images of the eyes were taken by an Eye Surface Profiler and processed by custom-built MATLAB codes. A dynamic light intensity frequency based white-to-white detection process and a novel three-dimensional method for limbus detection is presented. RESULTS: Evidence of significant differences (p<0.001) between nasal-temporal and superior-inferior white-to-white distances in both right and left eyes were found (nasal-temporal direction; 11.74±0.42 mm in right eyes and 11.82±0.47 mm in left eyes & superior-inferior direction; 11.52±0.45 mm in right eyes and 11.55±0.46 mm in left eyes). Average limbus nasal-temporal diameters were 13.64±0.55 mm for right eyes, and 13.74±0.40 mm for left eyes, however the superior-inferior diameters were 13.65±0.54 mm, 13.75±0.38 mm for right and left eyes, respectively. No significant difference in limbus contours has been observed either between the nasal-temporal direction (p = 0.91) and the superior-inferior direction (p = 0.83) or between the right (p = 0.18) and left eyes (p = 0.16). Evidence of tilt towards the nasal-temporal side in the three-dimensional shape of the limbus was found. The right eyes mean limbus contour tilt around the X-axis was -0.3±1.35° however, their mean limbus contour tilt around the Y-axis was 1.76±0.9°. Likewise, the left eyes mean limbus contour tilt around the X-axis was 0.77±1.25° and the mean limbus contour tilt around the Y-axis was -1.54±0.89°. CONCLUSIONS: The white-to-white distance in the human eye is significantly larger in the nasal-temporal direction than in the superior-inferior direction. The human limbus diameter was found not to vary significantly in these directions. The 3D measures show that the limbus contour does not lay in one plane and tends to be higher on the nasal-inferior side of the eye.
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spelling pubmed-62610092018-12-06 Three-dimensional non-parametric method for limbus detection Abass, Ahmed Lopes, Bernardo T. Eliasy, Ashkan Wu, Richard Jones, Steve Clamp, John Ambrósio, Renato Elsheikh, Ahmed PLoS One Research Article PURPOSE: To present a novel non-parametric algorithm for detecting the position of the human eye limbus in three dimensions and a new dynamic method for measuring the full 360° visible iris boundary known as white-to-white distance along the eye horizontal line. METHODS: The study included 88 participants aged 23 to 65 years (37.7±9.7), 47 females and 41 males. Clinical characteristics, height data and the apex coordinates and 1024×1280 pixel digital images of the eyes were taken by an Eye Surface Profiler and processed by custom-built MATLAB codes. A dynamic light intensity frequency based white-to-white detection process and a novel three-dimensional method for limbus detection is presented. RESULTS: Evidence of significant differences (p<0.001) between nasal-temporal and superior-inferior white-to-white distances in both right and left eyes were found (nasal-temporal direction; 11.74±0.42 mm in right eyes and 11.82±0.47 mm in left eyes & superior-inferior direction; 11.52±0.45 mm in right eyes and 11.55±0.46 mm in left eyes). Average limbus nasal-temporal diameters were 13.64±0.55 mm for right eyes, and 13.74±0.40 mm for left eyes, however the superior-inferior diameters were 13.65±0.54 mm, 13.75±0.38 mm for right and left eyes, respectively. No significant difference in limbus contours has been observed either between the nasal-temporal direction (p = 0.91) and the superior-inferior direction (p = 0.83) or between the right (p = 0.18) and left eyes (p = 0.16). Evidence of tilt towards the nasal-temporal side in the three-dimensional shape of the limbus was found. The right eyes mean limbus contour tilt around the X-axis was -0.3±1.35° however, their mean limbus contour tilt around the Y-axis was 1.76±0.9°. Likewise, the left eyes mean limbus contour tilt around the X-axis was 0.77±1.25° and the mean limbus contour tilt around the Y-axis was -1.54±0.89°. CONCLUSIONS: The white-to-white distance in the human eye is significantly larger in the nasal-temporal direction than in the superior-inferior direction. The human limbus diameter was found not to vary significantly in these directions. The 3D measures show that the limbus contour does not lay in one plane and tends to be higher on the nasal-inferior side of the eye. Public Library of Science 2018-11-26 /pmc/articles/PMC6261009/ /pubmed/30475843 http://dx.doi.org/10.1371/journal.pone.0207710 Text en © 2018 Abass et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Abass, Ahmed
Lopes, Bernardo T.
Eliasy, Ashkan
Wu, Richard
Jones, Steve
Clamp, John
Ambrósio, Renato
Elsheikh, Ahmed
Three-dimensional non-parametric method for limbus detection
title Three-dimensional non-parametric method for limbus detection
title_full Three-dimensional non-parametric method for limbus detection
title_fullStr Three-dimensional non-parametric method for limbus detection
title_full_unstemmed Three-dimensional non-parametric method for limbus detection
title_short Three-dimensional non-parametric method for limbus detection
title_sort three-dimensional non-parametric method for limbus detection
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6261009/
https://www.ncbi.nlm.nih.gov/pubmed/30475843
http://dx.doi.org/10.1371/journal.pone.0207710
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