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Yang Y, Vincent SJ, Cheung SW, Guo B, Cho P, Efron N. Characteristics of corneal microcysts in Hong Kong children wearing orthokeratology. Cont Lens Anterior Eye 2023; 46:102047. [PMID: 37626009 DOI: 10.1016/j.clae.2023.102047] [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: 03/23/2023] [Revised: 07/24/2023] [Accepted: 07/29/2023] [Indexed: 08/27/2023]
Abstract
PURPOSE To report the characteristics (prevalence, severity, and location) of corneal epithelial microcysts and investigate associated risk factors in children wearing orthokeratology (ortho-k) lenses. METHOD Ninety-five myopic children wearing ortho-k lenses (examined by one of three independent investigators from March to September 2020) were included in this retrospective cross-sectional study. Pertinent data at baseline before ortho-k treatment and at the aftercare visits (the first visit when the microcysts were observed for children with microcysts, and the last visit before October 2020 for children without microcysts) were retrieved and analysed. RESULTS A microcystic response was observed in 52.6% of children wearing ortho-k lenses. Children with high myopia (≥ 5.00 D) had a higher prevalence (100.0%, 23/23) and severity (69.5% (16/23) > grade 2 Efron scale) compared to children with low myopia (≤ 4.00 D) (prevalence of 37.5% (27/72) and 7.0% (5/72) > grade 2, p < 0.001). Microcysts were predominantly (86.0%) observed in the region of the inferior pigmented arc, typically originating in the inferior mid-peripheral cornea, and expanding over time into a semi- or whole annulus. Baseline myopia and topographical change at the treatment zone centre were significantly greater (p < 0.05) in low myopic children with microcysts (univariate analyses). CONCLUSIONS During the COVID-19 pandemic, probably due to lifestyle changes, microcysts were frequently observed in children wearing ortho-k lenses and were associated with higher baseline myopia. Practitioners should examine ortho-k wearers with caution using a slit lamp with high magnification and illumination, especially the mid-peripheral cornea. The use of highly oxygen permeable lenses and frequent aftercare are necessary for ortho-k wearers, especially those with higher myopia.
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Affiliation(s)
- Yajing Yang
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong.
| | - Stephen J Vincent
- Centre for Vision and Eye Research, School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Queensland, Australia; Contact Lens and Visual Optics Laboratory, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Sin W Cheung
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong
| | - Biyue Guo
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong
| | - Pauline Cho
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong
| | - Nathan Efron
- Centre for Vision and Eye Research, School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Queensland, Australia
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2
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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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3
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Moreno VC, Aguilella-Arzo M, Del Castillo RM, Espinós FJ, Del Castillo LF. A refined model on flow and oxygen consumption in the human cornea depending on the oxygen tension at the interface cornea/post lens tear film during contact lens wear. JOURNAL OF OPTOMETRY 2022; 15:160-174. [PMID: 33589396 PMCID: PMC9068744 DOI: 10.1016/j.optom.2020.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 12/04/2020] [Accepted: 12/29/2020] [Indexed: 05/23/2023]
Abstract
The study of oxygen consumption rate under" in vivo" human cornea during contact lens wear has been technically a challenge and several attempts have been made in the last 20 years to model the physiology of the human cornea during contact lens wear. Unfortunately, some of these models, based on a constant corneal oxygen consumption rate, produce areas on the cornea where the oxygen tension is negative, which has no physical sense. In order to avoid such inconsistency, different researchers have developed alternative models of oxygen consumption, which predict the likely oxygen metrics available at the interface cornea/post lens tear film by determination of oxygen flux, oxygen consumption, and oxygen tension through the different layers (endothelium, stroma, and epithelium). Although oxygen deficiency produces corneal edema, corneal swelling, hypoxia, acidosis, and other abnormalities, the estimation of the oxygen distribution below the impact of a contact lens wear is interesting to know which lens transmissibility was adequate to maintain the cornea and avoid epithelial and stromal anoxia. The estimation of minimum transmissibility for a lens for extended wear applications will be very useful for both clinicians and manufacturers. The aim of this work is to present a complete discussion based on Monod kinetics model that permits give an estimation of oxygen partial pressure distribution, the profile distribution of corneal flux and oxygen consumption rate, and finally the estimation of the relaxation mechanism of the cornea depending on the oxygen tension at the interface cornea/post lens tear film. Relaxation time in this context can quantify the capability of the corneal tissue to adapt to increasing concentrations of oxygen. It is proposed this parameter as a biological meaningful indicator of the interaction between contact lens polymers and living tissues such as the corneal cellular layer.
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Affiliation(s)
- Vicente Compañ Moreno
- Departmento de Termodinámica Aplicada. Escuela Técnica Superior de Ingenieros Industriales (ETSII), Universitat Politécnica de Valencia, Campus de Vera s / n, 46020 Valencia, Spain
| | | | - Roxana M Del Castillo
- Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Francisco J Espinós
- Centro de Investigación en Acuicultura y Medio Ambiente (ACUMA), Universitat Politècnica de València, Campus de Vera s / n, 46020 Valencia, Spain
| | - Luis Felipe Del Castillo
- Department of Polymers, Materials Research Institute, National Autonomous University of Mexico, Ap Postal 70-360, Coyoacan, Mexico City, Mexico
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4
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Walsh K, Jones L, Moody K. Addressing common myths and misconceptions in soft contact lens practice. Clin Exp Optom 2021; 105:459-473. [PMID: 34886744 DOI: 10.1080/08164622.2021.2003693] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Advances in contact lens technology over the past 50 years since the commercialisation of the first soft lenses in 1971 have been incredible, with significant changes in contact lens materials, frequency of replacement, care systems and lens designs occurring. However, despite the widespread availability of contact lenses, penetration rates for those who need vision correction remain in the low single digits and many practitioners seem to hold on to concepts around the potential value of contact lenses that appear based in the dim and distant past and are certainly no longer valid today. This review addresses 10 common 'myths and misconceptions' around soft contact lenses using an evidence-based approach that can hopefully dispel some of these incorrect assumptions.
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Affiliation(s)
- Karen Walsh
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada
| | - Lyndon Jones
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada.,Centre for Eye and Vision Research (CEVR), 17W Hong Kong Science Park, Shatin, Hong Kong
| | - Kurt Moody
- Johnson & Johnson Vision, Jacksonville, Florida, USA
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5
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Nguyen DCT, Dowling J, Ryan R, McLoughlin P, Fitzhenry L. Pharmaceutical-loaded contact lenses as an ocular drug delivery system: A review of critical lens characterization methodologies with reference to ISO standards. Cont Lens Anterior Eye 2021; 44:101487. [PMID: 34353748 DOI: 10.1016/j.clae.2021.101487] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 06/28/2021] [Accepted: 07/04/2021] [Indexed: 01/12/2023]
Abstract
Therapeutic contact lenses for ocular drug delivery have received considerable interest as they can potentially enhance ocular bioavailability, increase patient compliance, and reduce side effects. Along with the successful in vitro and in vivo studies on sustained drug delivery through contact lenses, lens critical properties such as water content, optical transparency and modulus have also been investigated. Aside from issues such as drug stability or burst release, the potential for the commercialization of pharmaceutical-loaded lenses can be limited by the alteration of lens physical and chemical properties upon the incorporation of therapeutic or non-therapeutic components. This review outlines advances in the use of pharmaceutical-loaded contact lenses and their relevant characterization methodologies as a potential ocular drug delivery system from 2010 to 2020, while summarizing current gaps and challenges in this field. A key reference point for this review is the relevant ISO standards on contact lenses, relating to the associated characterization methodologies. The content of this review is categorized based on the chemical, physical and mechanical properties of the loaded lens with the shortcomings of such analytical technologies examined.
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Affiliation(s)
- Dan Chau Thuy Nguyen
- Ocular Therapeutics Research Group (OTRG), Pharmaceutical & Molecular Biotechnology Research Centre (PMBRC), Waterford Institute of Technology, Waterford City, County Waterford X91 K0EK, Ireland.
| | - Joseph Dowling
- Research and Development Department, Bausch + Lomb Ireland Ltd., Waterford City, County Waterford X91 V383, Ireland
| | - Richie Ryan
- Ocular Therapeutics Research Group (OTRG), Pharmaceutical & Molecular Biotechnology Research Centre (PMBRC), Waterford Institute of Technology, Waterford City, County Waterford X91 K0EK, Ireland
| | - Peter McLoughlin
- Ocular Therapeutics Research Group (OTRG), Pharmaceutical & Molecular Biotechnology Research Centre (PMBRC), Waterford Institute of Technology, Waterford City, County Waterford X91 K0EK, Ireland
| | - Laurence Fitzhenry
- Ocular Therapeutics Research Group (OTRG), Pharmaceutical & Molecular Biotechnology Research Centre (PMBRC), Waterford Institute of Technology, Waterford City, County Waterford X91 K0EK, Ireland
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6
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Morgan PB, Murphy PJ, Gifford KL, Gifford P, Golebiowski B, Johnson L, Makrynioti D, Moezzi AM, Moody K, Navascues-Cornago M, Schweizer H, Swiderska K, Young G, Willcox M. CLEAR - Effect of contact lens materials and designs on the anatomy and physiology of the eye. Cont Lens Anterior Eye 2021; 44:192-219. [PMID: 33775377 DOI: 10.1016/j.clae.2021.02.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 02/01/2021] [Indexed: 12/19/2022]
Abstract
This paper outlines changes to the ocular surface caused by contact lenses and their degree of clinical significance. Substantial research and development to improve oxygen permeability of rigid and soft contact lenses has meant that in many countries the issues caused by hypoxia to the ocular surface have largely been negated. The ability of contact lenses to change the axial growth characteristics of the globe is being utilised to help reduce the myopia pandemic and several studies and meta-analyses have shown that wearing orthokeratology lenses or soft multifocal contact lenses can reduce axial length growth (and hence myopia). However, effects on blinking, ptosis, the function of Meibomian glands, fluorescein and lissamine green staining of the conjunctiva and cornea, production of lid-parallel conjunctival folds and lid wiper epitheliopathy have received less research attention. Contact lens wear produces a subclinical inflammatory response manifested by increases in the number of dendritiform cells in the conjunctiva, cornea and limbus. Papillary conjunctivitis is also a complication of all types of contact lenses. Changes to wear schedule (daily disposable from overnight wear) or lens materials (hydrogel from SiHy) can reduce papillary conjunctivitis, but the effect of such changes on dendritic cell migration needs further study. These changes may be associated with decreased comfort but confirmatory studies are needed. Contact lenses can affect the sensitivity of the ocular surface to mechanical stimulation, but whether these changes affect comfort requires further investigation. In conclusion, there have been changes to lens materials, design and wear schedules over the past 20+ years that have improved their safety and seen the development of lenses that can reduce the myopia development. However, several changes to the ocular surface still occur and warrant further research effort in order to optimise the lens wearing experience.
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Affiliation(s)
- Philip B Morgan
- Eurolens Research, Division of Pharmacy and Optometry, University of Manchester, UK.
| | - Paul J Murphy
- University of Waterloo, School of Optometry and Vision Science, Waterloo, Canada
| | - Kate L Gifford
- School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Australia
| | - Paul Gifford
- School of Optometry and Vision Science, UNSW Sydney, Australia
| | | | - Leah Johnson
- CooperVision Specialty EyeCare, Gilbert, AZ, United States
| | - Dimitra Makrynioti
- School of Health Rehabilitation Sciences, University of Patras (Aigio), Greece
| | - Amir M Moezzi
- Centre for Ocular Research and Education, University of Waterloo, Canada
| | - Kurt Moody
- Johnson & Johnson Vision Care, Jacksonville, FL, United States
| | | | | | - Kasandra Swiderska
- Eurolens Research, Division of Pharmacy and Optometry, University of Manchester, UK
| | | | - Mark Willcox
- School of Optometry and Vision Science, UNSW Sydney, Australia
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7
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Wei S, Yin R, Tang T, Wu Y, Liu Y, Wang P, Wang K, Mei M, Zou R, Duan X. Gas-Permeable, Irritation-Free, Transparent Hydrogel Contact Lens Devices with Metal-Coated Nanofiber Mesh for Eye Interfacing. ACS NANO 2019; 13:7920-7929. [PMID: 31251581 DOI: 10.1021/acsnano.9b02305] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
An electronic "smart" contact lens device with high gas permeability and optical transparency, as well as mechanical compliance and robustness, offers daily wear capability in eye interfacing and can have broad applications ranging from ocular diagnosis to augmented reality. Most existing contact lens electronics utilize gas-impermeable substrates, electronic components, and interfacial adhesion layers, which impedes them from applications requiring continuous daily wear. Here we report on the design and fabrication of an eye interfacing device with a commercial ocular contact lens as the substrate, metal-coated nanofiber mesh as the conductor, and in situ electrochemically deposited poly(3,4-ethylenedioxythiophene) (PEDOT) /poly(styrene sulfonate) (PSS) as the adhesion material. This hydrogel contact lens device shows high gas permeability, wettability, and level of hydration, in addition to excellent optical transparency, mechanical compliance, and robustness. Using a rabbit model, we found that the animals wearing these hydrogel contact lens devices continuously for 12 hours showed a level of corneal fluorescein staining comparable to those wearing pure hydrogel contact lenses for same period of time, with no obvious corneal abrasion or irritation, indicating their high level of safety for continuous daily wear. Finally, full-field electroretinogram (ERG) recordings on rabbits were carried out to demonstrate the functionality of this device. We believe that the strategy of integrating nanofiber mesh-based electronic components demonstrated here can offer a general platform for hydrogel electronics with the advantages of preserving the physiological and mechanical properties of the hydrogel, thus enabling seamless integration with biological tissues and providing various wearable or implantable sensors with improved biocompatibility for health monitoring or medical treatment.
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Affiliation(s)
- Shiyuan Wei
- Department of Biomedical Engineering, College of Engineering , Peking University , Beijing 100871 , China
- Academy for Advanced Interdisciplinary Studies , Peking University , Beijing 100871 , China
| | - Rongkang Yin
- Department of Biomedical Engineering, College of Engineering , Peking University , Beijing 100871 , China
- Academy for Advanced Interdisciplinary Studies , Peking University , Beijing 100871 , China
- Peking-Tsinghua Center for Life Sciences , Peking University , Beijing 100871 , China
| | - Tao Tang
- Department of Ophthalmology , Peking University People's Hospital , Beijing 100044 , China
- College of Optometry , Peking University Health Science Center , Beijing 100044 , China
| | - Yingxiao Wu
- Department of Materials Science and Engineering, College of Engineering , Peking University , Beijing 100871 , China
| | - Yang Liu
- Department of Biomedical Engineering, College of Engineering , Peking University , Beijing 100871 , China
| | - Puxin Wang
- Department of Biomedical Engineering, College of Engineering , Peking University , Beijing 100871 , China
- Academy for Advanced Interdisciplinary Studies , Peking University , Beijing 100871 , China
| | - Kai Wang
- Department of Ophthalmology , Peking University People's Hospital , Beijing 100044 , China
- College of Optometry , Peking University Health Science Center , Beijing 100044 , China
| | - Ming Mei
- WuXi App Tec (Suzhou) Co., Ltd. , Suzhou 215104 , China
| | - Ruqiang Zou
- Department of Materials Science and Engineering, College of Engineering , Peking University , Beijing 100871 , China
| | - Xiaojie Duan
- Department of Biomedical Engineering, College of Engineering , Peking University , Beijing 100871 , China
- Academy for Advanced Interdisciplinary Studies , Peking University , Beijing 100871 , China
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8
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Moezzi AM, Varikooty J, Luensmann D, Schulze MM, Ng A, Karkkainen T, Xu J, Jones L. The short-term physiological impact of switching reusable silicone hydrogel wearers into a hydrogel daily disposable multifocal. Clin Ophthalmol 2019; 13:1193-1202. [PMID: 31371916 PMCID: PMC6636608 DOI: 10.2147/opth.s208905] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Accepted: 05/14/2019] [Indexed: 01/14/2023] Open
Abstract
Purpose: To evaluate ocular physiological responses to etafilcon A multifocal (etMF) daily disposable (DD) lenses after 4 weeks of wear, when switching from habitual silicone hydrogel (SiHy) daily wear. Method: A single-arm, open-label, bilateral dispensing study was conducted in 39 habitual spherical SiHy wearers (14 hyperopes; 25 myopes). Clinical visits occurred with habitual SiHy (control) at baseline and after 4 weeks of etMF DD open-eye lens wear at exit. Objective limbal/bulbar hyperemia using the Oculus K5M (0–4) and subjective grading of lid wiper epitheliopathy (LWE) (0–4) were tested for non-inferiority (NI), using a margin of 1 grade. Corneal thickness along a 10 mm cord was measured using the Visante OCT and tested for NI using a 30 μm margin. Corneal staining area was graded (0–100%). Results: The least-square mean differences (LSMD) and 95% confidence interval (95% CI) between etMF DD and habitual SiHy in central and peripheral corneal thickness (μm) were 3.64 (−2.0, 9.29) and 3.0 (−7.72, 13.72) in hyperopic, and 3.56 (−0.66, 7.78) and 6.40 (−1.62, 14.42) in myopic subjects. The LSMD (95% CI) for bulbar and limbal hyperemia were −0.08 (−0.19, 0.02) and −0.01 (−0.12, 0.09) in hyperopes, and 0.04 (−0.03, 0.12) and 0.04 (−0.04, 0.11) in myopes. The LSMD (95% CI) for LWE were 0.11 (−0.39, 0.60) and 0.30 (−0.07, 0.67) for hyperopes and myopes, respectively. Conclusions: No clinically significant differences in a variety of physiological responses were found when habitual reusable SiHy daily wear subjects were refitted into hydrogel etMF, when the subjects were followed for 4 weeks.
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Affiliation(s)
- Amir M Moezzi
- Centre for Ocular Research & Education (CORE, formerly Centre for Contact Lens Research), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Jalaiah Varikooty
- Centre for Ocular Research & Education (CORE, formerly Centre for Contact Lens Research), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Doerte Luensmann
- Centre for Ocular Research & Education (CORE, formerly Centre for Contact Lens Research), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Marc-Matthias Schulze
- Centre for Ocular Research & Education (CORE, formerly Centre for Contact Lens Research), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Alison Ng
- Centre for Ocular Research & Education (CORE, formerly Centre for Contact Lens Research), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Thomas Karkkainen
- Research and Development, Johnson & Johnson Vision, Jacksonville, FL, USA
| | - Jing Xu
- Research and Development, Johnson & Johnson Vision, Jacksonville, FL, USA
| | - Lyndon Jones
- Centre for Ocular Research & Education (CORE, formerly Centre for Contact Lens Research), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
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Moezzi AM, Hutchings N, Fonn D, Simpson TL. Mixed Model Analysis of Between-Subject Variability in Overnight Corneal Swelling and Deswelling With Silicone Hydrogel Lenses. Invest Ophthalmol Vis Sci 2019; 59:2576-2585. [PMID: 29847665 DOI: 10.1167/iovs.17-23352] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To model between subject variability of corneal swelling (CS) and deswelling after overnight wear of silicone hydrogel (SiHy) contact lenses. Methods A total of 29 neophyte subjects wore 12 SiHy lenses with central transmissibility range of 31 to 211 Dk/t units on separate nights, in random order, and on one eye only. The contralateral eye served as the control. Central corneal thickness was measured using digital optical pachymetry before lens insertion, immediately after lens removal on waking, then 20, 40 minutes, 1, 2, and 3 hours later. Mixed modelling was conducted for simultaneous analysis of group and between-subject effects of CS and deswelling. Results The best model for overnight CS versus Dk/t was linear with a random intercept showing constant between-subject differences in CS for different Dk/t values. The best fit for corneal deswelling versus time was a curvilinear random intercept and random slope model. About 90% of the total between-subject deswelling variance in either lens or control eyes was due to the intercept variability with much less (∼10%) being due to the variability of the individual deswelling rate (slope). Subject age, sex, and ametropia were not predictors of individual corneal swelling in the swelling versus Dk/t analysis. Age, however, was a significant (inverse) predictor of the rate of corneal deswelling, only in lens-wearing eyes. Conclusions A large proportion of variability in corneal swelling is because of subject-specific differences in corneal response to hypoxia. This shows that "low swellers" and "high swellers" actually do exist.
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Affiliation(s)
- Amir M Moezzi
- Center for Ocular Research & Education (CORE, formerly Center for Contact Lens Research), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Natalie Hutchings
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Desmond Fonn
- Center for Ocular Research & Education (CORE, formerly Center for Contact Lens Research), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Trefford L Simpson
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
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10
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Mann A, Sáez‐Martinez V, Lydon F, Tighe B. Investigating the permeation properties of contact lenses and its influence on tear electrolyte composition. J Biomed Mater Res B Appl Biomater 2018; 107:1997-2005. [DOI: 10.1002/jbm.b.34291] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 10/30/2018] [Accepted: 11/10/2018] [Indexed: 01/09/2023]
Affiliation(s)
- Aisling Mann
- Biomaterials Research Unit, School of Engineering and Applied ScienceAston University Birmingham B4 7ET UK
| | - Virginia Sáez‐Martinez
- Biomaterials Research Unit, School of Engineering and Applied ScienceAston University Birmingham B4 7ET UK
| | - Fiona Lydon
- Biomaterials Research Unit, School of Engineering and Applied ScienceAston University Birmingham B4 7ET UK
| | - Brian Tighe
- Biomaterials Research Unit, School of Engineering and Applied ScienceAston University Birmingham B4 7ET UK
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11
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Comparison of Silicone Hydrogel and Hydrogel Daily Disposable Contact Lenses. Eye Contact Lens 2018; 44 Suppl 1:S167-S172. [PMID: 28099285 DOI: 10.1097/icl.0000000000000363] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To compare subjective, objective and safety performance of silicone hydrogel (SiHy) daily disposable (DD) with hydrogel (Hy) DD contact lenses. METHOD Retrospective analysis on approximately 40 participants (Px) each in 5 trials. Lenses grouped into SiHy (delefilcon A, somofilcon A, narafilcon A) and Hy (omafilcon A, nelfilcon A). Participants attended follow-up visits at baseline, 2 weeks, 1 and 3 months. Subjective ratings (1-10 scale), adverse events (percentage of Px), physiological variables (0-4 scale), and wearing time were collected at each visit and compared between groups. RESULT Trials enrolled 201 Px totally. No differences in age, sex, and lens wear experience were found between SiHy and Hy groups (P≥0.09). There was greater increase in limbal redness from baseline in Hy group (0.18±0.38 vs. 0.02±0.47, P<0.001), whereas conjunctival staining and indentation were less in Hy group (P<0.001). No differences in comfortable wearing time were found between groups (P=0.41), and comfort at insertion, during day, and end of day was also no different (P≥0.71). Incidence of corneal infiltrative events (SiHy vs. Hy: 6.7% vs. 2.5%; P=0.32) and mechanical adverse events (SiHy vs. Hy: 0.0% vs. 0.0%; P=1.00) were no different. CONCLUSION Though some statistical significance was found between the groups, these differences were within measurement error. Neither material types showed superiority in comfort, and adverse event rates were low with both material types. These findings suggest that choice of material is a patient and practitioner preference; however, for patients at risk of hypoxia-related complications, SiHy materials should be considered.
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12
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Abstract
Purpose To determine if the use of pigments or adding polyvinyl pyrrolidone during the fabrication of 1-DAY ACUVUE DEFINE (AD) brand contact lenses impacts open-eye corneal swelling compared with no lens wear (NLW). Methods A partial double-masked, randomized, bilateral crossover study was conducted in 24 Asian subjects using AD, 1-DAY ACUVUE DEFINE with Lacreon (ADL), NLW, and a control lens with no tint (1-DAY ACUVUE MOIST [AM]). Central corneal thickness was measured before insertion and immediately after removal after 8 ± 1 h of open-eye wear using an optical pachymeter in one eye. Corneal thickness along a 10-mm cord was measured in the contralateral eye using the Visante optical coherence tomographer (OCT). Corneal swelling was tested for noninferiority using a 5% margin. The endothelial bleb response was measured at baseline and 20 min after lens insertion using specular microscopy. Subjective grading of corneal staining and limbal/bulbar hyperemia were also monitored. Results After 8 ± 1 h of open-eye wear, central corneal swelling across the study lenses with either optical pachymeter or OCT methods was negligible. Peripheral corneal swelling least-square mean differences with OCT were −0.03% (95% confidence interval [95% CI], −0.65 to 0.58%) and −0.26% (95% CI, −0.87 to 0.36%) between AD and ADL and the control lens (AM), respectively, and 1.67% (95% CI, 1.06 to 2.29%) and 1.45% (95% CI, 0.84 to 2.06%) between AD and ADL and NLW, respectively. No endothelial blebs were observed. No clinically significant differences were distinguished between the lenses and NLW for corneal staining and limbal/bulbar hyperemia. Conclusions After 8 ± 1 h of open-eye wear, central and peripheral corneal swelling along the horizontal meridian with AD, ADL, AM, and NLW were equivalent. These results confirm that the addition of polyvinyl pyrrolidone or pigments to etafilcon A to obtain a limbal ring design have no impact on corneal swelling or limbal/bulbar hyperemia during normal open-eye wear.
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Compañ V, Aguilella-Arzo M, Del Castillo LF, Hernández SI, Gonzalez-Meijome JM. Analysis of the application of the generalized monod kinetics model to describe the human corneal oxygen-consumption rate during soft contact lens wear. J Biomed Mater Res B Appl Biomater 2016; 105:2269-2281. [PMID: 27459544 DOI: 10.1002/jbm.b.33764] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 06/02/2016] [Accepted: 07/11/2016] [Indexed: 11/10/2022]
Abstract
This work is an analysis of the application of the generalized Monod kinetics model describing human corneal oxygen consumption during soft contact lens wear to models previously used by Chhabra et al. (J Biomed Mater Res B Appl Biomater, 2009a;90:202-209, Optom Vis Sci 2009b;86:454-466) and Larrea and Büchler (Invest Ophthalmol Vis Sci 2009;50:1076-1080). We use oxygen tension from in vivo estimations provided by Bonanno [Bonanno et al., Invest Ophthalmol Vis Sci 2002;43:371-376, and Bonanno et al 2009]. We consider four hydrogel and six silicone hydrogel lenses. The cornea is considered a single homogeneous layer, with constant oxygen permeability regardless of the type of lens worn. Our calculations yield different values for the maximum oxygen consumption rate Qc,max , whith differents oxygen tensions (high and low pc ) at the cornea-tears interface. Surprisingly, for both models, we observe an increase in oxygen consumption near an oxygen tension of 105 mmHg until a maximum is reached, then decreasing for higher levels of oxygen pressure. That is, when lowering the pressure of oxygen, the parameter Qc,max initially increases depending on the intensity of the change in pressure. Which, it could be related with the variation of the pH. Furthermore, it is also noted that to greater reductions in pressure, this parameter decreases, possibly due to changes in the concentration of glucose related to the anaerobic respiration. The averaged in vivo human corneal oxygen consumption rate of 1.47 × 10-4 cm3 of O2 /cm3 tissue s, with Monod kinetics model, considering all the lenses studied, is smaller than the average oxygen consumption rate value obtained using the Larrea and Büchler model. The impact that these calculations have on the oxygen partial pressure available at different depths in the corneal tissue is presented and discussed, taking into consideration previous models used in this study. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2269-2281, 2017.
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Affiliation(s)
- V Compañ
- Departamento de Termodinámica Aplicada, Escuela Técnica Superior de Ingenieros Industriales (ETSII), Universidad Politécnica de Valencia, Valencia, Spain
| | - M Aguilella-Arzo
- Departamento de Física aplicada, Universitat Jaume I, Castellón, Spain
| | - L F Del Castillo
- Departamento de Polímeros, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México (UNAM), Ciudad Universitaria, Coyoacán, México, DF
| | - S I Hernández
- Unidad Multidiscliplinaria de Docencia e Investigación-Juriquilla, Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM), Juriquilla, Querétaro, México
| | - J M Gonzalez-Meijome
- Clinical & Experimental Optometry Research Lab, Center of Physics (Optometry), School of Sciences, University of Minho, Braga, Portugal
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Pajic B, Pajic-Eggspuchler B, Haefliger I. Continuous IOP Fluctuation Recording in Normal Tension Glaucoma Patients. Curr Eye Res 2011; 36:1129-38. [DOI: 10.3109/02713683.2011.608240] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Bojan Pajic
- Swiss Eye Research Foundation, Eye Clinic ORASIS,
Titlisstrasse, Reinach, Switzerland
- Division of Ophthalmology, Department of Clinical Neurosciences, University Hospitals of Geneva, Switzerland
- Eye Hospital VIDAR-ORASIS Swiss, University of Novi Sad, Faculty of Physics,
Novi Sad, Serbia
| | | | - Ivan Haefliger
- School of Medicine, University of Basel,
Basel, Switzerland
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15
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In Vitro Analysis of the Physical Properties of Contact Lens Blister Pack Solutions. Optom Vis Sci 2011; 88:493-501. [DOI: 10.1097/opx.0b013e3181ff9d39] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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17
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Abstract
PURPOSE A metabolic model is developed for cornea-contact-lens system to elucidate the role of glucose metabolism in oxygenation of the cornea and to gauge the role that contact lens oxygen transmissibility plays in avoiding hypoxia-induced corneal abnormalities for extended wear applications. METHODS Oxygen transport through the cornea and contact lens system is typically described by oxygen diffusion with reactive loss. Oxygen in the cornea, however, interacts with other metabolic species, specifically glucose, lactate ion, bicarbonate ion, hydrogen ion, and carbon dioxide via aerobic glycolysis (Krebs or tricarboxylic acid cycle) and anaerobic glycolysis. Here, corneal aerobic and anaerobic metabolic reactions are incorporated into a six-layer (endothelium, stroma, epithelium, postlens tear film, contact lens, and prelens tear film) steady-state continuum reaction-diffusion model to quantify oxygen transport. We also define a new index, the oxygen deficiency factor (ODF), for gauging corneal oxygenation. As opposed to other current gauges of hypoxia, ODF is a local and sensitive measure of both the extent and severity of corneal oxygen deprivation. RESULTS We calculate not only oxygenation of the cornea but also its coupled glucose, lactate, and acidosis behavior. For the first time, the metabolic shift from aerobic to anaerobic glycolysis is explicitly incorporated into the transport and consumption of oxygen in the cornea on closed-eye contact lens wear. Adoption of enzymatic Monod kinetics for the metabolic reactions permits realistic assessment of local species concentrations throughout the cornea. We find that anerobic-produced lactate transports out of the cornea into the anterior chamber, whereas buffering bicarbonate ion transports into the comea from the anterior chamber. CONCLUSIONS The coupling of oxygen with other reactive species in corneal metabolism provides useful insight into the transport of oxygen in cornea-contact-lens system. Specifically, we find that in addition to oxygen depletion and acidosis in the cornea, lactate concentration increases while glucose and bicarbonate concentrations decrease from the endothelium toward the epithelium. Unlike other indices of corneal oxygenation, ODF is sensitive specifically to regions of cornea with local oxygen deficiency. Accordingly, ODF is a useful physiologic index to assess the extent and severity of hypoxia in the cornea.
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Short-Term Corneal Endothelial Response to Wear of Silicone-Hydrogel Contact Lenses in East Asian Eyes. Eye Contact Lens 2008; 34:317-21. [DOI: 10.1097/icl.0b013e31818b7428] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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19
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Rabbit Models of Contact Lens–Associated Corneal Hypoxia: A Review of the Literature. Eye Contact Lens 2008; 34:160-5. [DOI: 10.1097/icl.0b013e31815788d7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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20
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Chhabra M, Prausnitz JM, Radke CJ. Polarographic Method for Measuring Oxygen Diffusivity and Solubility in Water-Saturated Polymer Films: Application to Hypertransmissible Soft Contact Lenses. Ind Eng Chem Res 2008. [DOI: 10.1021/ie071071a] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mahendra Chhabra
- Department of Chemical Engineering, University of California, Berkeley, California 94720, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Vision Science Group, University of California, Berkeley, California 94720
| | - John M. Prausnitz
- Department of Chemical Engineering, University of California, Berkeley, California 94720, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Vision Science Group, University of California, Berkeley, California 94720
| | - Clayton J. Radke
- Department of Chemical Engineering, University of California, Berkeley, California 94720, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Vision Science Group, University of California, Berkeley, California 94720
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Performance of Lotrafilcon B Silicone Hydrogel Contact Lenses in Experienced Low-Dk/t Daily Lens Wearers. Eye Contact Lens 2007; 33:272-7. [DOI: 10.1097/icl.0b013e31802f78c2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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24
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Zigler L, Cedrone R, Evans D, Helbert-Green C, Shah T. Clinical Evaluation of Silicone Hydrogel Lens Wear With a New Multipurpose Disinfection Care Product. Eye Contact Lens 2007; 33:236-43. [PMID: 17873626 DOI: 10.1097/icl.0b013e318030c959] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To evaluate subjective symptoms and clinical signs in silicone hydrogel contact lens wearers with three different multipurpose solution (MPS) lens care regimens. METHODS In a double-masked, randomized, concurrently controlled study, 233 subjects from 12 clinical sites wore one of two silicone hydrogel lens brands (ACUVUE Advance or Focus NIGHT & DAY) for 1 month on a daily-wear basis supported by a new reconditioning multipurpose disinfecting solution (MPDS) preserved with POLYQUAD and ALDOX, regimen 1 (OPTI-FREE RepleniSH Multi-Purpose Disinfecting Solution), or by one of two MPSs preserved with polyhexamethyl biguanide, regimen 2 (ReNu MultiPlus Multi-Purpose Solution No Rub Formula) or regimen 3 (Complete MoisturePLUS Multi-Purpose Solution). RESULTS Significant differences in favor of regimen 1 were found in subjective responses of subjects wearing ACUVUE Advance lenses. For Focus NIGHT & DAY lens wearers, regimen 1 was associated with significantly less corneal staining (severity [P=0.0019], area [P=0.0077]) than regimen 2 was. The average number of times per day that rewetting drops were used was significantly higher for subjects randomized to regimen 3 than for subjects using regimen 1. CONCLUSIONS The clinical performance of the new MPDS product with silicone hydrogel lenses was generally as good as or better than the two comparative polyhexamethyl biguanide-preserved MPSs. Clinical differences were evident between the products. Practitioners should be aware that MPS product choice for use with silicone hydrogel lenses may lead to different clinical outcomes, particularly in regard to stress on the ocular surface, as evidenced by the corneal staining response.
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Affiliation(s)
- Lamar Zigler
- Central Ohio Eye Care, Inc., Columbus, OH 43202, USA.
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Ichijima H, Cavanagh HD. How Rigid Gas-Permeable Lenses Supply More Oxygen to the Cornea Than Silicone Hydrogels: A New Model. Eye Contact Lens 2007; 33:216-23. [PMID: 17873624 DOI: 10.1097/01.icl.0000254523.63767.05] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To show the superiority of hyper-Dk rigid gas-permeable (RGP) lenses to silicone hydrogels from the viewpoint of total oxygen supply to the entire cornea. METHODS The simple model of fitting the cornea with a contact lens was divided into 1-mm steps from the center to the limbus, and the area of concentric ring zones was calculated. Precorneal oxygen tension (PO2) for each zone was calculated using the Brennan oxygen calculator, and by taking into account the area uncovered by the RGP lens and the lens thickness, the average precorneal PO2 was mathematically compared for wear of silicone hydrogel and RGP lenses. RESULTS The average precorneal PO2 of the RGP lens was superior to that of the silicone hydrogel lens under open- and closed-eye conditions because the precorneal PO2 in the uncovered areas of the cornea can supply large contributions. The PO2 of a silicone hydrogel lens with 125 x 10(-9) of oxygen transmissibility at center thickness (Dk/t(c)) was estimated as 45 mm Hg under closed-eye conditions. At the same value, the Dk/t(c) of an RGP lens with a diameter of 11.0 mm was estimated to be 90 x 10(-9). CONCLUSIONS To minimize hypoxia in extended wear, clinicians should consider that an RGP lens with a Dk/t(c) value of only 90 x 10(-9) is equivalent to a silicone hydrogel lens with a Dk/t(c) value of 125 x 10(-9), and even high Dk/t(c) values for RGP lenses will provide more total oxygen to the entire cornea than their hybrid silicone hydrogel counterparts.
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Joslin CE, Tu EY, Shoff ME, Booton GC, Fuerst PA, McMahon TT, Anderson RJ, Dworkin MS, Sugar J, Davis FG, Stayner LT. The association of contact lens solution use and Acanthamoeba keratitis. Am J Ophthalmol 2007; 144:169-180. [PMID: 17588524 PMCID: PMC2692658 DOI: 10.1016/j.ajo.2007.05.029] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Revised: 05/25/2007] [Accepted: 05/28/2007] [Indexed: 11/29/2022]
Abstract
PURPOSE To investigate Acanthamoeba keratitis (AK) risk factors. Diagnosis of AK, a rare but serious corneal infection, has recently increased significantly at the University of Illinois at Chicago (UIC) Cornea Service. DESIGN Retrospective case-control study. METHODS settings: University, tertiary care hospital. patients: Fifty-five AK cases with contact lens use were diagnosed between May 1, 2003 and September 15, 2006. Clinic-matched controls with contact lens use were recruited. Subjects completed surveys targeting lens hygiene, contact lens solution use, and water exposure. main outcome measure: Acanthamoeba keratitis. RESULTS Thirty-nine (73.6%) cases and 113 (65.3%) controls participated; 38 cases had complete contact lens data. Thirty-five of 38 cases (92.1%) and 47 of 100 controls (47.0%) used soft lenses. Analysis was performed on 30 cases and 39 controls with matched pairs with soft lens use. Exclusive use of Advance Medical Optics (AMO) Complete MoisturePlus Multi-Purpose Solution was independently associated with AK in multivariable analysis (55.2% vs 10.5%; odds ratio [OR], 16.67; 95% confidence interval [CI] 2.11 to 162.63; P = .008). However, 38.8% of cases reported no use of AMO Complete MoisturePlus Multi-Purpose Solution either alone or in combination with other solutions. Although not statistically significant, additional hygiene-related variables (solution "reuse," lack of "rubbing," and showering with lenses) suggest a pattern of risk. CONCLUSIONS AMO Complete MoisturePlus Multi-Purpose Solution use is independently associated with AK among soft contact lens users. However, it does not explain all cases, suggesting additional factors. Further research into environmental risk factors and hygiene practices is warranted, especially considering this is the second outbreak of an atypical, contact lens-related infection.
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Affiliation(s)
- Charlotte E Joslin
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA.
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Dillehay SM. Does the Level of Available Oxygen Impact Comfort in Contact Lens Wear?: A Review of the Literature. Eye Contact Lens 2007; 33:148-55. [PMID: 17502750 DOI: 10.1097/01.icl.0000245572.66698.b1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE Wear of low-Dk/t lenses has long been associated with signs and symptoms indicative of hypoxia and with patient symptoms of dryness and discomfort. Although patient discomfort during soft contact lens wear has been generally attributed to lens dehydration, research studies aimed at verifying that connection have been unsuccessful. With the advent of high-Dk/t silicone hydrogel lenses, not only have improvements in clinical signs of hypoxia been documented, but improvements in patient symptoms of dryness and discomfort also have been documented. This literature review was undertaken to examine historic and current literature to determine whether the level of available oxygen is associated with patient symptoms of dryness and discomfort. METHODS Literature was reviewed related to soft contact lens dehydration, corneal hypoxia, patient symptoms of dryness and discomfort, and current clinical studies of silicone hydrogel lens wear. RESULTS Through the years, the body of knowledge has grown supporting a connection between decreased levels of available oxygen to the cornea caused by low-Dk/t contact lens wear and negative impacts on the signs of corneal health and patient symptoms. CONCLUSIONS Available published literature suggests that many of these changes in patient signs and symptoms seen with low-Dk/t lens wear may be related to an inflammatory response. Clinical studies of high-Dk/t silicone hydrogel lenses further support a significant connection between the level of available oxygen during contact lens wear and improved patient symptoms of comfort, including dryness.
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28
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Haque S, Fonn D, Simpson T, Jones L. Corneal Refractive Therapy with Different Lens Materials, Part 1: Corneal, Stromal, and Epithelial Thickness Changes. Optom Vis Sci 2007; 84:343-8. [PMID: 17435518 DOI: 10.1097/opx.0b013e318042af1d] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To assess the corneal swelling response to two myopic correction corneal refractive therapy (CRT) lenses of varying Dk/t values, worn for a single night. Change in thickness of the total cornea, stroma, and epithelium was measured across the horizontal meridian using optical coherence tomography (OCT). METHODS In this double-masked, randomized study, twenty subjects wore a CRT design lens in each eye, manufactured from Menicon Z (MenZ; Dk/t = 91) and Equalens II (EqII; Dk/t = 47) materials. Baseline corneal thickness was measured centrally and at four points either side of the central cornea using OCT, the night before sleeping at the Centre for Contact Lens Research. The next morning, lenses were removed, and thickness measurements were repeated 1, 3, 6, and 12 h after removal. RESULTS On lens removal, the MenZ eye had central and paracentral corneal swelling (mean +/- SD) of 4.1 +/- 2.0% and 5.6 +/- 2.4%, and the EqII eye had 5.8 +/- 2.6% and 7.0 +/- 2.6%. These values were significantly different from baseline (ReANOVA; p < 0.001) and were different between lens materials (p < 0.001). The central epithelium thinned by 10.0 +/- 4.5% in the MenZ eye and by 10.2 +/- 8.5% in the EqII eye, with the mid-peripheral epithelium thickening by 13.4 +/- 7.9% in the MenZ eye and 18.3 +/- 9.8% in the EqII eye (all changes different from baseline p < 0.001). These epithelial values were not statistically different between materials (p > 0.05). Stromal swelling values on lens removal were 5.7 +/- 2.2% centrally and 5.5 +/- 3.0% mid-peripherally (MenZ) and 7.7 +/- 3.1% centrally and 6.6 +/- 2.9% mid-peripherally (EqII) (all p < 0.001 from baseline). Central stromal swelling was different between eyes at lens removal (p < 0.001). Stromal thickness in both eyes returned to baseline values within 3 h. CONCLUSION The higher-Dk/t MenZ material caused significantly less overnight corneal and stromal swelling than the Eqll material, which reinforces the need to prescribe lenses with high Dk/t for overnight wear. Neither central epithelial thinning nor paracentral thickening are significantly affected by Dk/t.
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Affiliation(s)
- Sameena Haque
- Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada
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Moezzi AM, Fonn D, Simpson TL. Overnight Corneal Swelling With Silicone Hydrogel Contact Lenses With High Oxygen Transmissibility. Eye Contact Lens 2006; 32:277-80. [PMID: 17099388 DOI: 10.1097/01.icl.0000224529.14273.26] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To compare central corneal swelling after 8 hours of sleep in eyes wearing 2 different silicone hydrogel lenses with high oxygen transmissibility. METHODS Twenty neophyte subjects were randomly assigned to wear a comfilcon A lens (CooperVision Inc) in one eye and a lotrafilcon A lens (CIBA Vision) in the contralateral eye for an 8-hour overnight period. The study was repeated with another 20 neophyte subjects wearing comfilcon A in one eye only and no lens in the contralateral control eye. Central corneal thickness was measured with optical pachometry before lens insertion, immediately after lens removal on waking, at 20 and 40 minutes, 1 hour, 2 hours and 3 hours. RESULTS There was no significant difference between the amount of overnight central corneal swelling induced by the 2 lenses (4.1% +/- 1.9% with comfilcon A vs. 4.0% +/- 1.7% with lotrafilcon A; P>0.05). The swelling of the comfilcon A lens-wearing eyes was significantly higher than that found in the non-lens-wearing contralateral eyes (4.5% +/- 2.1% vs. 3.0% +/- 1.7%; P<0.05). CONCLUSIONS The same amount of overnight corneal swelling was induced by the 2 study lenses. The higher overnight swelling observed with the comfilcon A lenses compared to the non-lens-wearing eyes is similar to that reported in the literature for studies using lotrafilcon A lenses.
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Affiliation(s)
- Amir M Moezzi
- Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada
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Fink BA, Mitchell GL, Hill RM. Rigid Gas-Permeable Contact Lens Base Curve Radius and Transmissibility Effects on Corneal Oxygen Uptake. Optom Vis Sci 2006; 83:740-4. [PMID: 17041319 DOI: 10.1097/01.opx.0000232806.06677.97] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE The purpose of this study is to determine the effects of rigid gas-permeable contact lens thickness, base curve radius, and material permeability on corneal hypoxic stress. METHODS Corneal oxygen uptake rates were measured with a Clark-type polarographic electrode on the right eye of 10 human subjects for the normal open eye (air) and after 5 minutes of static wear of rigid contact lenses of four cornea-to-contact lens base curve fitting relationships: 0.2 mm steeper-than-K (STK), 0.1 mm STK, on K, and 0.1 mm flatter-than-K (FTK). There were also four materials (polymethylmethacrylate [Dk=0], lotifocon B [OP-2, Dk=15.9], lotifocon A [OP-3, Dk=30], lotifocon C [OP-6; Dk=60]) and three center thicknesses (0.14, 0.28, and 0.53 mm for the OP-6 lenses and 0.14 mm for all other materials) with all other parameters being constant. Each subject participated in two identical sessions. A repeated-measures analysis of variance was performed to compare the mean response across lens materials/thicknesses and the four curvature values. RESULTS Significant differences were found only for lens material/thickness (p<0.0001). Although OP-2 and OP-6 (0.53 mm) were manufactured to have the same Dk/t, post hoc comparisons showed that the oxygen uptake rate with OP-6 (0.53 mm) was significantly lower. The same is also true for OP-3 and OP-6 (0.28 mm), with OP-6 (0.28 mm) having a significantly lower oxygen uptake rate. CONCLUSIONS In contrast to past studies with PMMA, cornea-to-contact lens base curve fitting relationship, with the lens materials and designs studied here, did not affect corneal hypoxic stress, and thick, high Dk lenses resulted in less change in corneal response than did thin, lower Dk lenses of the same Dk/t. This is attributed to the lens reservoir effect that has been previously described.
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Affiliation(s)
- Barbara A Fink
- The Ohio State University, College of Optometry, Columbus, Ohio 43210-1240, USA.
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