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Vila-Andrés R, Esteve-Taboada JJ, Micó V. Soft Contact Lens Engraving Characterization by Wavefront Holoscopy. SENSORS (BASEL, SWITZERLAND) 2024; 24:3492. [PMID: 38894283 PMCID: PMC11174835 DOI: 10.3390/s24113492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 05/17/2024] [Accepted: 05/26/2024] [Indexed: 06/21/2024]
Abstract
Permanent engravings on contact lenses provide information about the manufacturing process and lens positioning when they are placed on the eye. The inspection of their morphological characteristics is important, since they can affect the user's comfort and deposit adhesion. Therefore, an inverted wavefront holoscope (a lensless microscope based on Gabor's principle of in-line digital holography) is explored for the characterization of the permanent marks of soft contact lenses. The device, based on an in-line transmission configuration, uses a partially coherent laser source to illuminate the soft contact lens placed in a cuvette filled with a saline solution for lens preservation. Holograms were recorded on a digital sensor and reconstructed by back propagation to the image plane based on the angular spectrum method. In addition, a phase-retrieval algorithm was used to enhance the quality of the recovered images. The instrument was experimentally validated through a calibration process in terms of spatial resolution and thickness estimation, showing values that perfectly agree with those that were theoretically expected. Finally, phase maps of different engravings for three commercial soft contact lenses were successfully reconstructed, validating the inverted wavefront holoscope as a potential instrument for the characterization of the permanent marks of soft contact lenses. To improve the final image quality of reconstructions, the geometry of lenses should be considered to avoid induced aberration effects.
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Affiliation(s)
| | | | - Vicente Micó
- Department of Optics and Optometry and Vision Sciences, Faculty of Physics, Universitat de València, 46100 Burjassot, Spain
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Marto-Costa C, Toffoletto N, Salema-Oom M, Antunes AMM, Pinto CA, Saraiva JA, Silva-Herdade AS, Alvarez-Lorenzo C, Serro AP. Improved triamcinolone acetonide-eluting contact lenses based on cyclodextrins and high hydrostatic pressure assisted complexation. Carbohydr Polym 2024; 331:121880. [PMID: 38388063 DOI: 10.1016/j.carbpol.2024.121880] [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: 10/12/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024]
Abstract
Contact lenses (CLs) constitute an advantageous platform for the topical release of corticosteroids due to their prolonged contact with the eye. However, the lipophilic nature of corticosteroids hampers CLs' ability to release therapeutic amounts. Two approaches to improve loading and release of triamcinolone acetonide (TA) from poly(2-hydroxyethyl methacrylate)-based hydrogels were investigated: adding 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) to the monomers solution before polymerization (HEMA/i-CD) and an hydrogels' post-treatment with HP-β-CD (HEMA/p-CD). The effect of HP-β-CD and sterilization by high hydrostatic pressure (HHP) on the hydrogel properties (water content, oxygen and ion permeability, roughness, transmittance, and stiffness) was evaluated. The HEMA/i-CD hydrogels had stronger affinity for TA, sustaining its release for one day. HHP sterilization promoted the formation of cyclodextrin-TA complexes within the hydrogels, improving their drug-loading capacity »60 %. Cytotoxicity and irritability tests confirmed the safety of the therapeutic CLs. TA released from the hydrogels permeated through ocular tissues ex vivo and showed anti-inflammatory activity. Finally, a previously validated mathematical model was used to estimate the ability of the TA-loaded CLs to deliver therapeutic drug concentrations to the posterior part of the eye. Overall, HP-β-CD-containing CLs are promising candidates for the topical ocular application of TA as an alternative delivery system to intraocular injections.
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Affiliation(s)
- Carolina Marto-Costa
- Centro de Química Estrutural (CQE) - Institute of Molecular Sciences and Chemical Engineering Department, Instituto Superior Técnico - University of Lisbon, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; Egas Moniz Center for Interdisciplinary Research (CiiEM), Egas Moniz School of Health & Science, Campus Universitário, Quinta da Granja, 2829-511 Monte da Caparica, Almada, Portugal.
| | - Nadia Toffoletto
- Centro de Química Estrutural (CQE) - Institute of Molecular Sciences and Chemical Engineering Department, Instituto Superior Técnico - University of Lisbon, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; Egas Moniz Center for Interdisciplinary Research (CiiEM), Egas Moniz School of Health & Science, Campus Universitário, Quinta da Granja, 2829-511 Monte da Caparica, Almada, Portugal.
| | - Madalena Salema-Oom
- Egas Moniz Center for Interdisciplinary Research (CiiEM), Egas Moniz School of Health & Science, Campus Universitário, Quinta da Granja, 2829-511 Monte da Caparica, Almada, Portugal.
| | - Alexandra M M Antunes
- Centro de Química Estrutural (CQE) - Institute of Molecular Sciences and Chemical Engineering Department, Instituto Superior Técnico - University of Lisbon, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
| | - Carlos A Pinto
- LAQV-REQUIMTE, Chemical Engineering Department, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
| | - Jorge A Saraiva
- LAQV-REQUIMTE, Chemical Engineering Department, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
| | - Ana S Silva-Herdade
- Instituto de Bioquímica, Instituto de Medicina Molecular, Faculdade de Medicina - University of Lisbon, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal.
| | - Carmen Alvarez-Lorenzo
- Departamento de Farmacología, Farmacia y Tecnología Farmacéutica, I+DFarma (GI-1645), Facultad de Farmacia, Instituto de Materiales (iMATUS) and Health Research Institute of Santiago de Compostela (IDIS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
| | - Ana Paula Serro
- Centro de Química Estrutural (CQE) - Institute of Molecular Sciences and Chemical Engineering Department, Instituto Superior Técnico - University of Lisbon, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; Egas Moniz Center for Interdisciplinary Research (CiiEM), Egas Moniz School of Health & Science, Campus Universitário, Quinta da Granja, 2829-511 Monte da Caparica, Almada, Portugal.
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Zhu Q, Zhang Q, Fu DY, Su G. Polysaccharides in contact lenses: From additives to bulk materials. Carbohydr Polym 2023; 316:121003. [PMID: 37321708 DOI: 10.1016/j.carbpol.2023.121003] [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: 03/13/2023] [Revised: 04/26/2023] [Accepted: 05/07/2023] [Indexed: 06/17/2023]
Abstract
As the number of applications has increased, so has the demand for contact lenses comfort. Adding polysaccharides to lenses is a popular way to enhance comfort for wearers. However, this may also compromise some lens properties. It is still unclear how to balance the variation of individual lens parameters in the design of contact lenses containing polysaccharides. This review provides a comprehensive overview of how polysaccharide addition impacts lens wear parameters, such as water content, oxygen permeability, surface wettability, protein deposition, and light transmittance. It also examines how various factors, such as polysaccharide type, molecular weight, amount, and mode of incorporation into lenses modulate these effects. Polysaccharide addition can improve some wear parameters while reducing others depending on the specific conditions. The optimal method, type, and amount of added polysaccharides depend on the trade-off between various lens parameters and wear requirements. Simultaneously, polysaccharide-based contact lenses may be a promising option for biodegradable contact lenses as concerns regarding environmental risks associated with contact lens degradation continue to increase. It is hoped that this review will shed light on the rational use of polysaccharides in contact lenses to make personalized lenses more accessible.
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Affiliation(s)
- Qiang Zhu
- School of Pharmacy, Nantong University, Nantong 226001, China
| | - Qiao Zhang
- Department of Clinical Pharmacy, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Ding-Yi Fu
- School of Pharmacy, Nantong University, Nantong 226001, China
| | - Gaoxing Su
- School of Pharmacy, Nantong University, Nantong 226001, China.
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Ahn J, Choi M. The pH-induced physical properties of ionic contact lens material. Heliyon 2023; 9:e12996. [PMID: 36793947 PMCID: PMC9922922 DOI: 10.1016/j.heliyon.2023.e12996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 01/11/2023] [Accepted: 01/11/2023] [Indexed: 01/22/2023] Open
Abstract
The degree of protonation of contact lens materials is affected by the surrounding pH environment, due to the different pKa values. The swelling of ionic contact lenses is generally controlled by these factors which determines physical properties of contact lenses. The purpose of this study was to evaluate the pH dependence of the physical properties of contact lenses. The ionic etafilcon A and non-ionic hilafilcon B contact lenses were used in this study. The diameter, refractive power, equilibrium water content (EWC), and the amounts of freezable-free water (Wff), freezable-bound water (Wfb) and non-freezable water (Wnf) in the contact lens at each pH condition were measured. The diameter, refractive power and EWC of etafilcon A decreased with decreasing pH below 7.0 or 7.4, whereas hilafilcon B showed relatively constant values. The quantity of Wfb tended to increase with increasing pH, showing a relatively constant value above 7.0, whereas Wnf decreased. Hilafilcon B did not show changes in EWC and specific trends in Wfb and Wnf. The significant change of etafilcon A at more acidic condition is derived from the presence of methacrylic acid (MA) which makes it vulnerable to pH. Additionally, though the EWC is composed of various states of water, (i) various states of water could response to surrounding environment in different way with EWC and (ii) Wfb could be the crucial factor that determines physical properties of contact lens.
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Affiliation(s)
- Jihye Ahn
- Department of Optometry, College of Energy and Biotechnology, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Moonsung Choi
- Department of Optometry, College of Energy and Biotechnology, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea,Convergence Institute of Biomedical Engineering and Biomaterials, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea,Corresponding author. Mugung Hall Rm419, 232, Gongneung-ro, Nowon-gu, Seoul, Republic of Korea.
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The impact of a rub and rinse regimen on removal of human coronaviruses from contemporary contact lens materials. Cont Lens Anterior Eye 2022; 45:101719. [PMID: 35643848 PMCID: PMC9124925 DOI: 10.1016/j.clae.2022.101719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/12/2022] [Accepted: 05/15/2022] [Indexed: 11/20/2022]
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Influence of Selected Ophthalmic Fluids on the Wettability and Hydration of Hydrogel and Silicone Hydrogel Contact Lenses—In Vitro Study. MATERIALS 2022; 15:ma15030930. [PMID: 35160876 PMCID: PMC8839750 DOI: 10.3390/ma15030930] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 01/11/2022] [Accepted: 01/20/2022] [Indexed: 11/16/2022]
Abstract
This study attempts to evaluate the effect of incubation in selected ophthalmic fluids on contact lenses (Etafilcon A, Omafilcon A, Narafilcon A, Senofilcon A). Four research groups differing in the incubation environment were created: (1) initial state, (2) contact lens solution (CLS), (3) contact lens solution and eye drops (ED) and (4) eye drops. Dehydration by gravimetric method and the contact angle (CA) by the sessile drop method were tested. The surface free energy (SFE) was also calculated with the use of several methods: Owens–Wendt, Wu, Neumann, and Neumann–Kwok. The greatest changes in the dehydration profile were observed for contact lenses incubated in ED. The most noticeable changes in CA values were observed for contact lenses incubated in ED, in which it was not possible to settle water drop after incubation. On the basis of SFE analysis, higher values were found for hydrogel contact lenses, e.g., according to the Owens–Wendt method, they ranged from 54.45 ± 6.56 mJ/m2 to 58.09 ± 4.86 mJ/m2, while in the case of silicone-hydrogel contact lenses, they ranged from 32.86 ± 3.47 mJ/m2 to 35.33 ± 6.56 mJ/m2. Incubation in all tested environments decreased the SFE values, but the differences were in most cases statistically insignificant. Calculating the SFE may be a useful method as it can be used to estimate the possibility of bacteria adhering to contact lens surfaces.
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Intrasession Repeatability of the Contact Angle Measured Using the Captive Bubble Method and Agreement Assessed Between Different Analysis Software Programs. Eye Contact Lens 2021; 46:385-390. [PMID: 31469756 DOI: 10.1097/icl.0000000000000655] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES The material biocompatibility of hydrogel and silicone hydrogel (SiHy) contact lens (CL) is of paramount importance in CL wear because a decrease in CL wettability reduces wearer comfort and increases wearer dropout. The aim of this study is to report on the repeatability and agreement between two different software programs that measure the contact angle with the captive bubble method in marketed CLs, which will help to translate this information into clinical practice. METHODS The contact angle of 23 different CLs was measured with the captive bubble method using 2 software programs: FTÅ200 and ImageJ. Three consecutive measurements were conducted for each CL. Reproducibility, repeatability, and agreement values were calculated according to the British Standards Institute and the International Organization for Standardization. RESULTS All methods showed good repeatability values in both CL materials (coefficient of variation <1.51%, Sw <2.26°, intraclass correlation coefficient >0.89, and the range of limits of agreement was between 7.22° and 7.57°). Higher concordance was achieved between the spherical and nonspherical options when using FTÅ200 software than when using ImageJ software. Statistically significant differences (P<0.05) between the 2 software programs were found, and they ranged between 5° and 10°. CONCLUSIONS The captive bubble method showed great repeatability in measuring the contact angle in marketed CLs with both software programs (FTÅ200 and ImageJ) assessed in this study. However, differences in the measured contact angles suggest that these techniques are not interchangeable. Therefore, standardization is recommended for contact angle measurement in hydrogel CL materials to facilitate comparisons, to improve clinical use of this information, and to analyze their impact in CL user comfort.
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Mordmuang A, Udomwech L, Karnjana K. Influence of Contact Lens Materials and Cleaning Procedures on Bacterial Adhesion and Biofilm Formation. Clin Ophthalmol 2021; 15:2391-2402. [PMID: 34135567 PMCID: PMC8197623 DOI: 10.2147/opth.s310862] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/10/2021] [Indexed: 11/30/2022] Open
Abstract
Purpose The present study aimed to compare the existing soft contact lens (CL) materials regarding their influence on bacterial biofilm formation and adhesion susceptibility. Then, the study was designed to investigate the effectiveness of various disinfecting solutions and evaluate the ability of cleaning regimens in terms of anti-bacterial adhesion and biofilm removal on different soft CL materials. Methods Bacterial biofilm formation on CLs was evaluated by biomass assay. Adhesion assay and standard plate count were carried out at time-interval periods within 24 h. Various CL disinfecting procedures were assessed for their efficacy to remove biofilm and reduce bacterial adhesion. Scanning electron microscopy (SEM) was performed for the morphological assessment of bacterial biofilm. Results Printed hydroxyethyl methacrylate (HEMA) CLs significantly demonstrated more biofilm staining and bacterial attachment when compared with non-printed HEMA CLs, while the Filcon II 3 and Nesofilcon A CLs possessed less biofilm biomass and adherent cells. Staphylococcus aureus and Pseudomonas aeruginosa represented the highest biofilm producing bacteria on HEMA-based materials in this study. The disinfecting regimen with the highest efficacy was the two-step system, first using multipurpose disinfecting solution containing edetate disodium and sorbic acid (MPDS+EDSA), followed by soaking in multipurpose solution (MPS). The regimen demonstrated the greatest effect against the pre-formed biofilm and the adhesion activity of S. aureus and P. aeruginosa on the soft CLs. The SEM micrographs confirmed the morphological changes of bacterial biofilm after disinfecting and revealed that the two-step system treated CLs displayed less adherent bacteria. Conclusion HEMA-based soft CLs may facilitate bacterial biofilm formation and adhesion capability. The two-step system was the most effective regimen for biofilm removal, where the soaking period in the disinfecting solution of the no-rub regimen should last more than 6 h to remove pre-formed biofilm.
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Affiliation(s)
| | - Lunla Udomwech
- School of Medicine, Walailak University, Nakhon Si Thammarat, Thailand.,Walailak University Hospital, Walailak University, Nakhon Si Thammarat, Thailand
| | - Kulwadee Karnjana
- School of Medicine, Walailak University, Nakhon Si Thammarat, Thailand
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CLEAR - Contact lens wettability, cleaning, disinfection and interactions with tears. Cont Lens Anterior Eye 2021; 44:157-191. [DOI: 10.1016/j.clae.2021.02.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 02/01/2021] [Indexed: 12/15/2022]
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Alves M, Castanheira EMS, Lira M. Interactions between contact lenses and lens care solutions: Influence in optical properties. Cont Lens Anterior Eye 2021; 44:101414. [PMID: 33579643 DOI: 10.1016/j.clae.2021.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 01/15/2021] [Accepted: 01/23/2021] [Indexed: 10/22/2022]
Abstract
PURPOSE Investigate changes in optical properties of contact lenses materials (transmittance and reflectance) and lens care solutions (absorption and fluorescence) resulting from its interaction. METHODS From an experimental study, triplicate measurements of transmittance and reflectance of five contact lenses (Senofilcon A, Lotrafilcon B, Balafilcon A, Comfilcon A, and Omafilcon A), as well as UV-vis absorption and fluorescence of four lens care solutions (LCS) (ReNu MultiPlus, Biotrue, OPTI-FREE PureMoist, and AOSept Plus), were evaluated before and after 8 h, one day and one week in storage. The outcomes were provided by Shimadzu UV3101-PC UV-vis-NIR spectrophotometer equipped with an integrating sphere, between 200-700 nm, and SPEX-Fluorolog 2 FL3-22 spectrofluorometer. RESULTS All variables exhibited statistically significant differences over time. Comfilcon A showed the lowest ultraviolet radiation (UVR) A & B attenuation. Balafilcon A and Lotrafilcon B displayed a slight suppression of UVR. Senofilcon A was effective in UVR protection and showed less effect on the fluorescence of lens care solutions. Overall, the reflectance decreased after storage (p < 0.05). AOSept Plus absorbance and fluorescence demonstrated lower interactions than multipurpose solutions (MPS), and Lotrafilcon B induced more remarkable changes in optical properties of LCS than the other materials. CONCLUSION The findings suggest that optical variables of lens care solutions and contact lenses changed mutually after storage, probably associated with biochemical and biophysical interactions between components and the release of some polymer compounds. These findings can provide additional information about the interaction of CL materials and LCS in clinical behavior.
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Affiliation(s)
- Micael Alves
- Centre of Physics, School of Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
| | - Elisabete M S Castanheira
- Centre of Physics, School of Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Madalena Lira
- Centre of Physics, School of Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
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Smith SM, Zhu D, Pierre D, Gilbert JL, Chinn JA. Effect of multipurpose care solutions upon physical dimensions of silicone hydrogel contact lenses. J Biomed Mater Res B Appl Biomater 2020; 108:1915-1924. [DOI: 10.1002/jbm.b.34533] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 10/10/2019] [Accepted: 11/12/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Stephanie M. Smith
- Department of BioengineeringClemson University Clemson South Carolina
- Clemson‐Medical University of South Carolina Bioengineering Program Charleston South Carolina
| | - Dongkai Zhu
- Department of BioengineeringClemson University Clemson South Carolina
- Clemson‐Medical University of South Carolina Bioengineering Program Charleston South Carolina
| | - David Pierre
- Department of BioengineeringClemson University Clemson South Carolina
- Clemson‐Medical University of South Carolina Bioengineering Program Charleston South Carolina
| | - Jeremy L. Gilbert
- Department of BioengineeringClemson University Clemson South Carolina
- Clemson‐Medical University of South Carolina Bioengineering Program Charleston South Carolina
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Moro A, Fagnola M, Picarazzi S, Di Dio A, Pastori V, Lecchi M, Tavazzi S. Hydrogen-peroxide and silicone-hydrogel contact lenses: Worsening of external eye condition and tear film instability. Cont Lens Anterior Eye 2017; 41:157-161. [PMID: 29066042 DOI: 10.1016/j.clae.2017.10.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 10/07/2017] [Accepted: 10/09/2017] [Indexed: 10/18/2022]
Abstract
PURPOSE The aim is discussing the origins of worsening of external eye condition (EEC) and of tear film (TF) instability after wear of silicone-hydrogel contact lenses (CLs) with hydrogen-peroxide (H2O2) care system. METHODS EEC and TF stability were evaluated before and after 15days of wear combined with different care systems: (1) H2O2, (2) detergent solution and H2O2, (3) multipurpose solution (MPS), (4) H2O2 and artificial tears. In-vitro cell mortality tests were performed after 24h cell incubation with CLs treated with H2O2. Photon correlation spectroscopy (PCS) was carried out on tears of non-wearers and CL wearers who used MPS or H2O2 solution. RESULTS Worsening of EEC was observed only for the group using H2O2 (group 1). In-vitro, cell mortality was found higher for worn CL than for unworn CLs. Worsening of TF stability was observed regardless of care system and also PCS results on tears of CL wearers were found different compared to non-wearers regardless of care system. The only observed remedy for tear instability of CL wearers was found to be the administration of artificial tears. CONCLUSIONS Worsening of EEC of CL wearers using H2O2 is attributed to H2O2 scarce cleaning efficacy, which can be solved by adding a CL detergent solution. The origin of TF instability is found to be different. A remedy was found to be the administration of artificial tears, whose effect could be attributed either to the role of specific components or to rinsing and replacement of TF during wear.
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Affiliation(s)
- A Moro
- Materials Science Department, University of Milano Bicocca, Via Cozzi 55, I-20125 Milan, Italy
| | - M Fagnola
- COMiB, University of Milano Bicocca, Via Cozzi 55, I-20125 Milan, Italy
| | - S Picarazzi
- Materials Science Department, University of Milano Bicocca, Via Cozzi 55, I-20125 Milan, Italy
| | - A Di Dio
- Materials Science Department, University of Milano Bicocca, Via Cozzi 55, I-20125 Milan, Italy
| | - V Pastori
- University of Milano Bicocca, Department of Biotechnology and Bioscience, Piazza della Scienza 2, I-20126 Milan, Italy; COMiB, University of Milano Bicocca, Via Cozzi 55, I-20125 Milan, Italy
| | - M Lecchi
- University of Milano Bicocca, Department of Biotechnology and Bioscience, Piazza della Scienza 2, I-20126 Milan, Italy; COMiB, University of Milano Bicocca, Via Cozzi 55, I-20125 Milan, Italy
| | - S Tavazzi
- Materials Science Department, University of Milano Bicocca, Via Cozzi 55, I-20125 Milan, Italy; COMiB, University of Milano Bicocca, Via Cozzi 55, I-20125 Milan, Italy.
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Picarazzi S, Lecchi M, Pastori V, D'Arienzo M, Scotti R, Tavazzi S. Photon correlation spectroscopy applied to tear analysis. Colloids Surf B Biointerfaces 2017; 157:26-30. [PMID: 28570988 DOI: 10.1016/j.colsurfb.2017.05.057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/19/2017] [Accepted: 05/22/2017] [Indexed: 10/19/2022]
Abstract
This study aims to deepen the knowledge on tear film properties by the development of a protocol for analyses of Photon Correlation Spectroscopy (PCS) on human tears and by the comparison between PCS results obtained on tears of contact lens wearers and non-wearers. Tears (5μL) were collected by a glass capillary. The analyses provide the hydrodynamic diameter of tear components by analyzing intensity fluctuations in time of scattered light. PCS appears a promising technique for studying tear features and for shedding light on specific eye conditions, such as on the clinical effects of CL wear. In fact, statistical difference (p<0.001) was found between the measured mean hydrodynamic diameter of tear components of wearers and non-wearers, the resulting value significantly higher for CL wearers. The scenario does not substantially change after (25±5)min from the CL removal. The difference is attributed to changes in the interactions between tear constituents due to CL wear. In order to get deeper insights on the influence of CL wear on aggregation and structure of tear components, a preliminary Electron Spin Resonance (ESR) investigation was performed, monitoring Fe3+ species. ESR spectra on tears of both CL wearers and non-wearers showed the presence of intense signals, probably associated to iron (III) centers in proteins such as lactoferrin, and a weaker resonance attributable to Fe3+ species interacting with S-S bridges of lysozyme. Differences in ESR spectra between CL wearers and non-wearers were detected and tentatively ascribed to changes in coordination or in local environment of Fe3+ centers connected to aggregation phenomena induced by CL wear, which promote their interaction with other neighboring iron species.
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Affiliation(s)
- S Picarazzi
- University of Milano Bicocca, Materials Science Department, Via R. Cozzi 55, I-20125 Milan, Italy
| | - M Lecchi
- University of Milano Bicocca, Department of Biotechnology and Bioscience, Piazza Della Scienza 2, I-20126 Milan, Italy; University of Milano Bicocca, COMiB, Via R. Cozzi 55, I-20125 Milan, Italy
| | - V Pastori
- University of Milano Bicocca, Department of Biotechnology and Bioscience, Piazza Della Scienza 2, I-20126 Milan, Italy; University of Milano Bicocca, COMiB, Via R. Cozzi 55, I-20125 Milan, Italy
| | - M D'Arienzo
- University of Milano Bicocca, Materials Science Department, Via R. Cozzi 55, I-20125 Milan, Italy; University of Milano Bicocca, COMiB, Via R. Cozzi 55, I-20125 Milan, Italy
| | - R Scotti
- University of Milano Bicocca, Materials Science Department, Via R. Cozzi 55, I-20125 Milan, Italy; University of Milano Bicocca, COMiB, Via R. Cozzi 55, I-20125 Milan, Italy
| | - S Tavazzi
- University of Milano Bicocca, Materials Science Department, Via R. Cozzi 55, I-20125 Milan, Italy; University of Milano Bicocca, COMiB, Via R. Cozzi 55, I-20125 Milan, Italy.
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