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Open AccessArticle

Determination of Optic Axes by Corneal Topography among Italian, Brazilian, and Chinese Populations

1
School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
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Department of Ophthalmology, Federal University of São Paulo, São Paulo 04021, Brazil
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Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, UK
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Humanitas San Pio X Hospital, 20159 Milano, Italy
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School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou 325035, China
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Key Laboratory of Vision Science, Ministry of Health, Wenzhou 325035, China
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Humanitas Clinical and Research Center—IRCCS Rozzano, 20089 Rozzan, Italy
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Department of Biomedical Sciences, Humanitas University, 20090 Pieve Emanuel, Italy
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Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Urca, Rio de Janeiro 22290, Brazil
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Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100083, China
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NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London EC1V 2PD, UK
*
Author to whom correspondence should be addressed.
Academic Editors: Pablo Pérez-Merino, Andres Vasquez Quintero and Jos J. Rozema
Photonics 2021, 8(2), 61; https://doi.org/10.3390/photonics8020061
Received: 18 December 2020 / Revised: 10 February 2021 / Accepted: 11 February 2021 / Published: 23 February 2021
(This article belongs to the Special Issue Visual Optics and Ophthalmology)
This study aims to describe a new universal method to identify the relative three-dimensional directions of visual, pupillary, and optical axes of the eye and the angles between them using topography elevation data. The method was validated in a large clinical cohort, and ethnical differences were recorded. Topography elevation data were collected from 1992 normal eyes of 966 healthy participants in Italy, Brazil, and China. The three main axes were defined as follows: optical axis (OA) was defined as the optimal path of light that passes through the ocular system without refraction. The pupillary axis (PA) line was defined using X and Y coordinates of the pupil centre with the chamber depth, in addition to the centre of a sphere fitted to the central 3 mm diameter of the cornea. The visual axis (VA) was taken by its best approximation, the coaxially sighted corneal light reflex. The alpha angle was measured between the VA and OA, and the kappa angle between the VA and PA. The average values of kappa and alpha angles were 3.41 ± 2.84 and 6.04 ± 2.43 in the Italian population, 2.6 ± 1.53 and 5.87 ± 2.3 in the Brazilian population, and 2.09 ± 1.22 and 3.85 ± 1.48 in the Chinese population. View Full-Text
Keywords: cornea; topography; optical axis; visual axis; pupillary axis; kappa angle; alpha angle cornea; topography; optical axis; visual axis; pupillary axis; kappa angle; alpha angle
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MDPI and ACS Style

Lopes, B.T.; Eliasy, A.; Elhalwagy, M.; Vinciguerra, R.; Bao, F.; Vinciguerra, P.; Ambrósio, R., Jr.; Elsheikh, A.; Abass, A. Determination of Optic Axes by Corneal Topography among Italian, Brazilian, and Chinese Populations. Photonics 2021, 8, 61. https://doi.org/10.3390/photonics8020061

AMA Style

Lopes BT, Eliasy A, Elhalwagy M, Vinciguerra R, Bao F, Vinciguerra P, Ambrósio R Jr., Elsheikh A, Abass A. Determination of Optic Axes by Corneal Topography among Italian, Brazilian, and Chinese Populations. Photonics. 2021; 8(2):61. https://doi.org/10.3390/photonics8020061

Chicago/Turabian Style

Lopes, Bernardo T.; Eliasy, Ashkan; Elhalwagy, Mohamed; Vinciguerra, Riccardo; Bao, Fangjun; Vinciguerra, Paolo; Ambrósio, Renato, Jr.; Elsheikh, Ahmed; Abass, Ahmed. 2021. "Determination of Optic Axes by Corneal Topography among Italian, Brazilian, and Chinese Populations" Photonics 8, no. 2: 61. https://doi.org/10.3390/photonics8020061

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