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Sobczak M, Asejczyk M, Wilczyński M. The effect of pupil size on the measurement of corneal birefringence properties: preliminary study. Sci Rep 2023; 13:17439. [PMID: 37838761 PMCID: PMC10576786 DOI: 10.1038/s41598-023-44706-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 10/11/2023] [Indexed: 10/16/2023] Open
Abstract
We used a partial Mueller matrix polarimeter to measure the corneal anisotropic properties at three pupil sizes (dilated, natural, and constricted). The geometrical parameters of first order isochromes were described by quadrilaterals. These parameters are statistically significantly different between the three pupil sizes. The pupillary size changes do not influence the azimuth angle distribution α. The retardation R and birefringence distributions show asymmetry in the nasal-temporal cross-section. There are differences between pupil sizes for both nasal and temporal parts of the cornea for these distributions. Iridial light scattering and diffraction might be the reason for these differences.
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Affiliation(s)
- Marcelina Sobczak
- Department of Optics and Photonics, Wrocław University of Science and Technology, Wybrzeże Stanisława Wyspiańskiego 27, 50-370, Wrocław, Poland.
- School of Optometry, Indiana University, 800 Atwater, Bloomington, IN, 47405, United States.
| | - Magdalena Asejczyk
- Department of Optics and Photonics, Wrocław University of Science and Technology, Wybrzeże Stanisława Wyspiańskiego 27, 50-370, Wrocław, Poland
| | - Maciej Wilczyński
- Faculty of Pure and Applied Mathematics, Wrocław University of Science and Technology, Wybrzeże Stanisława Wyspiańskiego 27, 50-370, Wrocław, Poland
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Vilbert M, Bocheux R, Georgeon C, Borderie V, Pernot P, Irsch K, Plamann K. A new method for in vivo assessment of corneal transparency using spectral-domain OCT. PLoS One 2023; 18:e0291613. [PMID: 37796869 PMCID: PMC10553212 DOI: 10.1371/journal.pone.0291613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 09/02/2023] [Indexed: 10/07/2023] Open
Abstract
Corneal transparency is essential to provide a clear view into and out of the eye, yet clinical means to assess such transparency are extremely limited and usually involve a subjective grading of visible opacities by means of slit-lamp biomicroscopy. Here, we describe an automated algorithm allowing extraction of quantitative corneal transparency parameters with standard clinical spectral-domain optical coherence tomography (SD-OCT). Our algorithm employs a novel pre-processing procedure to standardize SD-OCT image analysis and to numerically correct common instrumental artifacts before extracting mean intensity stromal-depth (z) profiles over a 6-mm-wide corneal area. The z-profiles are analyzed using our previously developed objective method that derives quantitative transparency parameters directly related to the physics of light propagation in tissues. Tissular heterogeneity is quantified by the Birge ratio Br and the photon mean-free path (ls) is determined for homogeneous tissues (i.e., Br~1). SD-OCT images of 83 normal corneas (ages 22-50 years) from a standard SD-OCT device (RTVue-XR Avanti, Optovue Inc.) were processed to establish a normative dataset of transparency values. After confirming stromal homogeneity (Br <10), we measured a median ls of 570 μm (interdecile range: 270-2400 μm). By also considering corneal thicknesses, this may be translated into a median fraction of transmitted (coherent) light Tcoh(stroma) of 51% (interdecile range: 22-83%). Excluding images with central saturation artifact raised our median Tcoh(stroma) to 73% (interdecile range: 34-84%). These transparency values are slightly lower than those previously reported, which we attribute to the detection configuration of SD-OCT with a relatively small and selective acceptance angle. No statistically significant correlation between transparency and age or thickness was found. In conclusion, our algorithm provides robust and quantitative measurements of corneal transparency from standard SD-OCT images with sufficient quality (such as 'Line' and 'CrossLine' B-scan modes without central saturation artifact) and addresses the demand for such an objective means in the clinical setting.
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Affiliation(s)
- Maëlle Vilbert
- Laboratory for Optics and Biosciences (LOB)— École Polytechnique, CNRS, INSERM, IPP, Palaiseau, France
- Vision Institute—CNRS, INSERM, Sorbonne University, Paris, France
- GRC 32, Transplantation et Thérapies Innovantes de la Cornée, Sorbonne Université, Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, Paris, France
| | - Romain Bocheux
- Laboratory for Optics and Biosciences (LOB)— École Polytechnique, CNRS, INSERM, IPP, Palaiseau, France
- GRC 32, Transplantation et Thérapies Innovantes de la Cornée, Sorbonne Université, Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, Paris, France
- Physical Chemistry Institute (ICP)—CNRS, University of Paris-Saclay, Orsay, France
| | - Cristina Georgeon
- GRC 32, Transplantation et Thérapies Innovantes de la Cornée, Sorbonne Université, Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, Paris, France
| | - Vincent Borderie
- GRC 32, Transplantation et Thérapies Innovantes de la Cornée, Sorbonne Université, Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, Paris, France
| | - Pascal Pernot
- Physical Chemistry Institute (ICP)—CNRS, University of Paris-Saclay, Orsay, France
| | - Kristina Irsch
- Vision Institute—CNRS, INSERM, Sorbonne University, Paris, France
- GRC 32, Transplantation et Thérapies Innovantes de la Cornée, Sorbonne Université, Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, Paris, France
| | - Karsten Plamann
- Laboratory for Optics and Biosciences (LOB)— École Polytechnique, CNRS, INSERM, IPP, Palaiseau, France
- LOA—ENSTA Paris, École polytechnique, CNRS, IPP, Palaiseau, France
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Sobczak M, Asejczyk M. Birefringent properties of the cornea measured by a Mueller type polarimeter in healthy adults and children. BIOMEDICAL OPTICS EXPRESS 2021; 12:7872-7885. [PMID: 35003872 PMCID: PMC8713654 DOI: 10.1364/boe.440274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 10/30/2021] [Accepted: 10/31/2021] [Indexed: 06/14/2023]
Abstract
Mueller type polarimeter was used for in vivo measurements of the anisotropic parameters (retardation and azimuth angle) of corneas. To determine birefringence, corneal thickness was measured with a Scheimpflug camera (Corvist ST). The retardation distributions in the nasal-temporal cross-section in both children (N=7) and adults (N=38) groups occurred asymmetrical. The asymmetry in birefringence distributions was observed only in adults group. The geometrical analysis of the first order isochromes in both age groups showed the asymmetry of its shapes. The changes of symmetry in birefringent properties with age may have potential relationship with changing corneal biometry.
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Sobczak M, Asejczyk M, Kalinowski K, Pierścionek B. Comparative analysis of the corneal birefringence pattern in healthy children and adults. Ophthalmic Physiol Opt 2021; 41:715-725. [PMID: 34021615 DOI: 10.1111/opo.12835] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 03/30/2021] [Indexed: 12/17/2022]
Abstract
PURPOSE To undertake a comparative analysis of the corneal shape, thickness and isochromatics in the eyes of children and adults in order to determine the extent of similarities and differences between the cohorts. METHODS The study involved 24 children (aged 8 years) and 37 young White adults (aged between 22-24 years) with no apparent or known health or ocular conditions. Measurements were made of corneal radius of curvature, both central (CCT) and paracentral (PCT) corneal thickness and intraocular pressure (IOP). Images of the isochromatics were captured using a slit lamp and a circular polarizer. The geometry of fringe I and II of the isochromatics was analysed. RESULTS Statistically significant differences were found between CCT and PCT in nasal and temporal regions for both the children and adult cohorts. The same trends were observed in the radii of the cornea. Statistically significant differences between side lengths and angles of isochromatic fringes were found. No differences in asymmetry of shape for fringe I between adults and children were detected; greater symmetry was seen in fringe II in children than for adults. CONCLUSIONS The asymmetry in corneal shape and curvature contributes to the shape of the isochromatic fringes. This is likely linked to the orientation and parameters of the collagen fibres and to the muscles' forces, and be relevant for surgical procedures such as corneal transplantation.
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Affiliation(s)
- Marcelina Sobczak
- Department of Optics and Photonics, Wroclaw University of Science and Technology, Wrocław, Poland
| | - Magdalena Asejczyk
- Department of Optics and Photonics, Wroclaw University of Science and Technology, Wrocław, Poland
| | - Kamil Kalinowski
- Department of Optics and Photonics, Wroclaw University of Science and Technology, Wrocław, Poland
| | - Barbara Pierścionek
- School of Life Sciences and Education, Staffordshire University, Stoke-on-Trent, UK.,Faculty of Health, Education, Medicine and Social Care, Anglia Ruskin University, Chelmsford, UK
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Temple SE, McGregor JE, Miles C, Graham L, Miller J, Buck J, Scott-Samuel NE, Roberts NW. Perceiving polarization with the naked eye: characterization of human polarization sensitivity. Proc Biol Sci 2016; 282:rspb.2015.0338. [PMID: 26136441 PMCID: PMC4528539 DOI: 10.1098/rspb.2015.0338] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Like many animals, humans are sensitive to the polarization of light. We can detect the angle of polarization using an entoptic phenomenon called Haidinger's brushes, which is mediated by dichroic carotenoids in the macula lutea. While previous studies have characterized the spectral sensitivity of Haidinger's brushes, other aspects remain unexplored. We developed a novel methodology for presenting gratings in polarization-only contrast at varying degrees of polarization in order to measure the lower limits of human polarized light detection. Participants were, on average, able to perform the task down to a threshold of 56%, with some able to go as low as 23%. This makes humans the most sensitive vertebrate tested to date. Additionally, we quantified a nonlinear relationship between presented and perceived polarization angle when an observer is presented with a rotatable polarized light field. This result confirms a previous theoretical prediction of how uniaxial corneal birefringence impacts the perception of Haidinger's brushes. The rotational dynamics of Haidinger's brushes were then used to calculate corneal retardance.We suggest that psychophysical experiments, based upon the perception of polarized light, are amenable to the production of affordable technologies for self-assessment and longitudinal monitoring of visual dysfunctions such as age-related macular degeneration.
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Affiliation(s)
- Shelby E. Temple
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
- e-mail:
| | | | - Camilla Miles
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Laura Graham
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Josie Miller
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Jordan Buck
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
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Westphal P, Kaltenbach JM, Wicker K. Corneal birefringence measured by spectrally resolved Mueller matrix ellipsometry and implications for non-invasive glucose monitoring. BIOMEDICAL OPTICS EXPRESS 2016; 7:1160-74. [PMID: 27446644 PMCID: PMC4929629 DOI: 10.1364/boe.7.001160] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 02/05/2016] [Accepted: 02/06/2016] [Indexed: 05/18/2023]
Abstract
A good understanding of the corneal birefringence properties is essential for polarimetric glucose monitoring in the aqueous humor of the eye. Therefore, we have measured complete 16-element Mueller matrices of single-pass transitions through nine porcine corneas in-vitro, spectrally resolved in the range 300…1000 nm. These ellipsometric measurements have been performed at several angles of incidence at the apex and partially at the periphery of the corneas. The Mueller matrices have been decomposed into linear birefringence, circular birefringence (i.e. optical rotation), depolarization, and diattenuation. We found considerable circular birefringence, strongly increasing with decreasing wavelength, for most corneas. Furthermore, the decomposition revealed significant dependence of the linear retardance (in nm) on the wavelength below 500 nm. These findings suggest that uniaxial and biaxial crystals are insufficient models for a general description of the corneal birefringence, especially in the blue and in the UV spectral range. The implications on spectral-polarimetric approaches for glucose monitoring in the eye (for diabetics) are discussed.
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Irsch K, Gramatikov BI, Wu YK, Guyton DL. Improved eye-fixation detection using polarization-modulated retinal birefringence scanning, immune to corneal birefringence. OPTICS EXPRESS 2014; 22:7972-7988. [PMID: 24718173 DOI: 10.1364/oe.22.007972] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present an improved method for remote eye-fixation detection, using a polarization-modulated approach to retinal birefringence scanning (RBS), without the need for individual calibration or separate background measurements and essentially independent of corneal birefringence. Polarization-modulated RBS detects polarization changes generated in modulated polarized light passing through a unique pattern of nerve fibers identifying and defining the retinal region where fixation occurs (the fovea). A proof-of-concept demonstration in human eyes suggests that polarization-modulated RBS has the potential to reliably detect true foveal fixation on a specified point with an accuracy of at least ± 0.75°, and that it can be applied to the general population, including individuals with sub-optimal eyes and young children, where early diagnosis of visual problems can be critical. As could be employed in an eye-controlled display or in other devices, polarization-modulated RBS also enables and paves the way for new and reliable eye-fixation-evoked human-machine interfaces.
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