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Tarnawska D, Jastrzebska M, Chrobak E, Kadela-Tomanek M, Weglarz B, Boryczka G, Dobrowolski D, Chełmecka E, Wrzalik R. Endogenous fluorescence can differentiate the keratoconic cornea. Exp Eye Res 2019; 181:178-184. [PMID: 30735658 DOI: 10.1016/j.exer.2019.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 01/03/2019] [Accepted: 02/03/2019] [Indexed: 11/15/2022]
Abstract
The purpose of the study was to investigate the endogenous fluorescence of the keratoconic cornea in order to analyze changes in the spectra due to the keratoconic stroma abnormalities. Twenty-two corneal buttons obtained from patients with keratoconus (KC, N = 22) at the time of penetrating keratoplasty were used. As a reference, twelve normal corneas (N = 12): ten from the Eye Bank and two from enucleated eyes due to choroidal melanoma were used. The fluorescence excitation/emission matrices (EEM) in the ranges of 250-400/260-600 nm were recorded. Healthy cornea, keratoconic cornea and sclera showed three main EEM bands, which correspond to the following fluorophores: tryptophan residues in the proteoglycan fraction of corneal/scleral stromas, naturally occurring collagen cross-links and the NAD(P)H fraction present in the metabolically active cells. Relative intensity factors S1, S2 and S3 describing the contribution of each kind of fluorophore to the total fluorescence of the tissue were calculated. Normal and keratoconic corneas show qualitatively similar fluorescence matrices, but the statistically significant differences in the mean values of the S1, S2 and S3 parameters for the KC and normal corneas were observed indicating changes in contribution of different fluorophores to the whole fluorescence of the tissue. Moreover, differences between multidimensional distribution of the relative intensity factors S1, S2 and S3 between these groups were demonstrated (p < 0.001). In conclusions: Differences in the relative intensity factors calculated on a basis of the fluorescence spectra can correspond to the changes found in the KC stroma regarding natural collagen cross-links and the proteoglycan fraction. These parameters well differentiate the KC and normal corneas that could serve as an additional tool for the keratoconus characterization.
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Affiliation(s)
- Dorota Tarnawska
- Department of Biophysics and Molecular Physics, A. Chelkowski Institute of Physics, Silesian Center for Education and Interdisciplinary Research, University of Silesia, 41-500 Chorzów, 75 Pułku Piechoty 1A, Poland; Department of Ophthalmology, District Railway Hospital, Panewnicka 65, 40-760 Katowice, Poland
| | - Maria Jastrzebska
- Department of Solid State Physics, A. Chelkowski Institute of Physics, Silesian Center for Education and Interdisciplinary Research, University of Silesia, 41-500 Chorzów, 75 Pułku Piechoty 1A, Poland.
| | - Elwira Chrobak
- Department of Organic Chemistry, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia in Katowice, 41-200 Sosnowiec, Jagiellońska 4, Poland
| | - Monika Kadela-Tomanek
- Department of Organic Chemistry, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia in Katowice, 41-200 Sosnowiec, Jagiellońska 4, Poland
| | - Beata Weglarz
- Department of Ophthalmology, District Railway Hospital, Panewnicka 65, 40-760 Katowice, Poland
| | - Grzegorz Boryczka
- Faculty of Medicine in Katowice, Medical University of Silesia, 40-752 Katowice, Medyków 18, Poland
| | - Dariusz Dobrowolski
- Department of Ophthalmology with Pediatric Unit & Tissue and Cells Bank, St. Barbara Hospital, Trauma Center, Plac Medyków 1, 41-200 Sosnowiec, Poland; Chair and Clinical Department of Ophthalmology, Faculty of Medicine and Division of Dentistry in Zabrze, Medical University of Silesia, 40-760 Katowice, Panewnicka 65, Poland
| | - Elżbieta Chełmecka
- Department of Statistics, School of Pharmacy with the Division of Laboratory Medicine, Medical University of Silesia, 41-200 Sosnowiec, Ostrogórska 30, Poland; Department of Instrumental Analysis, School of Pharmacy with the Division of Laboratory Medicine, Medical University of Silesia, 41-200 Sosnowiec, Ostrogórska 30, Poland
| | - Roman Wrzalik
- Department of Biophysics and Molecular Physics, A. Chelkowski Institute of Physics, Silesian Center for Education and Interdisciplinary Research, University of Silesia, 41-500 Chorzów, 75 Pułku Piechoty 1A, Poland
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Matteini P, Sbrana F, Tiribilli B, Pini R. Atomic force microscopy and transmission electron microscopy analyses of low-temperature laser welding of the cornea. Lasers Med Sci 2008; 24:667-71. [DOI: 10.1007/s10103-008-0617-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Accepted: 09/05/2008] [Indexed: 11/29/2022]
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Matteini P, Rossi F, Menabuoni L, Pini R. Microscopic characterization of collagen modifications induced by low-temperature diode-laser welding of corneal tissue. Lasers Surg Med 2007; 39:597-604. [PMID: 17868101 DOI: 10.1002/lsm.20532] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND AND OBJECTIVE Laser welding of corneal tissue that employs diode lasers (810 nm) at low power densities (12-20 W/cm(2)) in association with Indocyanine Green staining of the wound is a technique proposed as an alternative to conventional suturing procedures. The aim of this study is to evaluate, by means of light (LM) and transmission electron microscopy (TEM) analyses, the structural modifications induced in laser-welded corneal stroma. MATERIALS AND METHODS Experiments were carried out in 20 freshly enucleated pig eyes. A 3.5 mm in length full-thickness cut was produced in the cornea, and was then closed by laser welding. Birefringence modifications in samples stained with picrosirius red dye were analyzed by polarized LM to assess heat damage. TEM analysis was performed on ultra-thin slices, contrasted with uranyl acetate and lead citrate, in order to assess organization and size of type I collagen fibrils after laser welding. RESULTS LM evidenced bridges of collagen bundles between the wound edges, with a loss of regular lamellar organization at the welded site. Polarized LM indicated that birefringence properties were mostly preserved after laser treatment. TEM examinations revealed the presence of quasi-ordered groups of fibrils across the wound edges preserving their interfibrillar spacing. These fibrils appeared morphologically comparable to those in the control tissue, indicating that type I collagen was not denatured during the diode laser corneal welding. CONCLUSIONS The preservation of substantially intact, undenatured collagen fibrils in laser-welded corneal wounds supported the thermodynamic studies that we carried out recently, which indicated temperatures below 66 degrees C at the weld site under laser irradiation. This observation enabled us to hypothesize that the mechanism, proposed in the literature, of unwinding of collagen triple helixes followed by fibrils "interdigitation" is not likely to occur in the welding process that we set up for the corneal suturing.
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Affiliation(s)
- Paolo Matteini
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata Nello Carrara, Sesto Fiorentino, Italy
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