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Phan CM, Wy Chan V, Drolle E, Hui A, Ngo W, Bose S, Shows A, Liang S, Sharma V, Subbaraman L, Zheng Y, Shi X, Wu J, Jones L. Evaluating the in vitro wettability and coefficient of friction of a novel and contemporary reusable silicone hydrogel contact lens materials using an in vitro blink model. Cont Lens Anterior Eye 2024; 47:102129. [PMID: 38423868 DOI: 10.1016/j.clae.2024.102129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 02/09/2024] [Accepted: 02/20/2024] [Indexed: 03/02/2024]
Abstract
PURPOSE To evaluate the in vitro wettability and coefficient of friction of a novel amphiphilic polymeric surfactant (APS), poly(oxyethylene)-co-poly(oxybutylene) (PEO-PBO) releasing silicone hydrogel (SiHy) contact lens material (serafilcon A), compared to other reusable SiHy lens materials. METHODS The release of fluorescently-labelled nitrobenzoxadiazole (NBD)-PEO-PBO was evaluated from serafilcon A over 7 days in a vial. The wettability and coefficient of friction of serafilcon A and three contemporary SiHy contact lens materials (senofilcon A; samfilcon A; comfilcon A) were evaluated using an in vitro blink model over their recommended wearing period; t = 0, 1, 7, 14 days for all lens types and t = 30 days for samfilcon A and comfilcon A (n = 4). Sessile drop contact angles were determined and in vitro non-invasive keratographic break-up time (NIKBUT) measurements were assessed on a blink model via the OCULUS Keratograph 5 M. The coefficient of friction was measured using a nano tribometer. RESULTS The relative fluorescence of NBD-PEO-PBO decreased in serafilcon A by approximately 18 % after 7 days. The amount of NBD-PEO-PBO released on day 7 was 50 % less than the amount released on day 1 (6.5±1.0 vs 3.4±0.5 µg/lens). The reduction in PEO-PBO in the lens also coincided with an increase in contact angles for serafilcon A after 7 days (p < 0.05), although there were no changes in NIKBUT or coefficient of friction (p > 0.05). The other contact lens materials had stable contact angles and NIKBUT over their recommended wearing period (p > 0.05), with the exception of samfilcon A, which had an increase in contact angle after 14 days as compared to t = 0 (p < 0.05). Senofilcon A and samfilcon A also showed an increase in coefficient of friction at 14 and 30 days, respectively, compared to their blister pack values (p < 0.05). CONCLUSION The results indicate that serafilcon A gradually depletes its reserve of PEO-PBO over 1 week, but this decrease did not significantly change the lens performance in vitro during this time frame.
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Affiliation(s)
- Chau-Minh Phan
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada; Centre for Eye and Vision Research (CEVR), 17W Hong Kong Science Park, Hong Kong, China.
| | - Vivian Wy Chan
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Elizabeth Drolle
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Alex Hui
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada; School of Optometry and Vision Science, Faculty of Medicine and Health, UNSW Sydney, Australia
| | - William Ngo
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada; Centre for Eye and Vision Research (CEVR), 17W Hong Kong Science Park, Hong Kong, China
| | - Susmita Bose
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Amanda Shows
- Alcon Research LLC, Fort Worth TX & Johns Creek, GA, USA
| | - Shuang Liang
- Alcon Research LLC, Fort Worth TX & Johns Creek, GA, USA
| | - Vinay Sharma
- Alcon Research LLC, Fort Worth TX & Johns Creek, GA, USA
| | | | - Ying Zheng
- Alcon Research LLC, Fort Worth TX & Johns Creek, GA, USA
| | - Xinfeng Shi
- Alcon Research LLC, Fort Worth TX & Johns Creek, GA, USA
| | - James Wu
- Alcon Research LLC, Fort Worth TX & Johns Creek, GA, USA
| | - Lyndon Jones
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada; Centre for Eye and Vision Research (CEVR), 17W Hong Kong Science Park, Hong Kong, China
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Phan CM, Ross M, Fahmy K, McEwen B, Hofmann I, Chan VWY, Clark-Baba C, Jones L. Evaluating Viscosity and Tear Breakup Time of Contemporary Commercial Ocular Lubricants on an In Vitro Eye Model. Transl Vis Sci Technol 2023; 12:29. [PMID: 37382574 PMCID: PMC10318592 DOI: 10.1167/tvst.12.6.29] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 05/31/2023] [Indexed: 06/30/2023] Open
Abstract
Purpose To evaluate the link between the viscosity of ophthalmic formulation and tear film stability using a novel in vitro eye model. Methods The viscosities and noninvasive tear breakup time (NIKBUT) of 13 commercial ocular lubricants were measured to evaluate the correlation between viscosity and NIKBUT. The complex viscosity of each lubricant was measured three times for each angular frequency (ranging from 0.1 to 100 rad/s) using the Discovery HR-2 hybrid rheometer. The NIKBUT measurements were performed eight times for each lubricant using an advanced eye model mounted on the OCULUS Keratograph 5M. A contact lens (CL; ACUVUE OASYS [etafilcon A]) or a collagen shield (CS) was used as the simulated corneal surface. Phosphate-buffered saline was used as a simulated fluid. Results The results showed a positive correlation between viscosity and NIKBUT at high shear rates (at 10 rad/s, r = 0.67) but not at low shear. This correlation was even better for viscosities between 0 and 100 mPa*s (r = 0.85). Most of the lubricants tested in this study also had shear-thinning properties. OPTASE INTENSE, I-DROP PUR GEL, I DROP MGD, OASIS TEARS PLUS, and I-DROP PUR had higher viscosity in comparison to other lubricants (P < 0.05). All of the formulations had a higher NIKBUT than the control (2.7 ± 1.2 seconds for CS and 5.4 ± 0.9 seconds for CL) without any lubricant (P < 0.05). I-DROP PUR GEL, OASIS TEARS PLUS, I-DROP MGD, REFRESH OPTIVE ADVANCED, and OPTASE INTENSE had the highest NIKBUT using this eye model. Conclusions The results show that the viscosity is correlated with NIKBUT, but further work is necessary to determine the underlying mechanisms. Translational Relevance The viscosity of ocular lubricants can affect NIKBUT and tear film stability, so it is an important property to consider when formulating ocular lubricants.
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Affiliation(s)
- Chau-Minh Phan
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
- Centre for Eye and Vision Research (CEVR), Hong Kong
| | - Mitchell Ross
- Department of Chemical Engineering, McMaster University, Hamilton, ON, Canada
| | | | | | | | - Vivian W. Y. Chan
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Connor Clark-Baba
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Lyndon Jones
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
- Centre for Eye and Vision Research (CEVR), Hong Kong
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Ponzini E, Recchioni A, Cheloni R, Zeri F, Tavazzi S. Physical Properties and Interaction With the Ocular Surface of Water-Gradient Contact Lenses. Eye Contact Lens 2023; 49:152-159. [PMID: 36811833 DOI: 10.1097/icl.0000000000000974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
ABSTRACT Since the introduction of silicone hydrogel contact lenses, many silicone-hydrogel materials have been produced, including water-gradient contact lenses with a silicone hydrogel core and a thin hydrogel outer layer (e.g., delefilcon A, verofilcon A, and lehfilcon A). Their properties have been investigated in various studies assessing both the chemical-physical characteristics and the comfort, but the overall picture is not always consistent. In this study, water-gradient technology is reviewed by looking at basic physical properties both in vitro and in vivo and at the interaction with the human ocular surface. Surface and bulk dehydration, surface wetting and dewetting, shear stress, interaction with tear components and with other environmental compounds, and comfort are discussed.
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Affiliation(s)
- Erika Ponzini
- Materials Science Department (E.P., F.Z., S.T.), University of Milano Bicocca, Via R. Cozzi 55-I-20125 Milan, Italy; COMiB Research Center (E.P., F.Z., S.T.), University of Milano Bicocca, Via R. Cozzi 55-I-20125 Milan, Italy; Academic Unit of Ophthalmology (A.R.), Institute of Inflammation and Ageing, University of Birmingham, UK; Birmingham and Midland Eye Centre (A.R.), Birmingham, UK; Optometry & Vision Sciences Group (A.R.), School of Life & Health Sciences, Aston University, Birmingham, 8UK; UCL Institute of Ophthalmology (R.C.), London, UK; and College of Health and Life Sciences (F.Z.), Aston University, Aston Triangle, Birmingham, B4 7ET, UK
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Marx S, Baluschev S, Sickenberger W. Solution-related in Vitro Dewetting Behavior of Various Daily Disposable Contact Lenses. Optom Vis Sci 2022; 99:750-757. [PMID: 36095059 PMCID: PMC9553268 DOI: 10.1097/opx.0000000000001939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
SIGNIFICANCE The dewetting process of contact lenses (CLs) is a result of material and solution properties as well as environmental factors. This article describes an investigational approach to observe and describe dewetting characteristics of different CL material and solution combinations. PURPOSE This study aimed to determine the in vitro dewetting characteristics of various daily disposable CLs that were assessed using a noninvasive keratograph dewetting procedure (noninvasive keratograph dry-up time). In vitro dewetting data of the same CL materials soaked in saline solution and artificial tear solution (ATS) were measured to determine additional dewetting characteristics. METHODS Noninvasive keratograph dry-up time was measured for six different soft CL materials and three different test conditions, in their specific blister solution, after exposure to saline and an ATS. Twenty CLs of each solution/material combination were assessed after an 8-hour soaking, during a 180-second dewetting observation, and the results were expressed by area under the curve values. RESULTS Fastest dewetting occurred for all materials when measured out of saline, indicated by the highest averaged area under the curve value of 9243.3 ± 38.3 over all lens materials. Slower dewetting was detected for all materials when measured out of their specific blister solution (7755.9 ± 37.1) and out of ATS (7988.8 ± 40.0). Intragroup results were statistically significantly different for all solutions showing the smallest differences within the ATS group ( P < .001, Kruskal-Wallis test). CONCLUSIONS A pure saline thin film is not an ideal representation of a complex tear film layer of a healthy human because it lacks any evaporative protection by a lipid layer. The use of an ATS, which more likely mimics the natural tear film, allowed in this experimental in vitro project to decrease the gap to the in vivo field. In vitro dewetting information in connection with the blister solution allows only a theoretical conclusion about the initial lens wear after lens insertion.
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Affiliation(s)
- Sebastian Marx
- JenVis Research GbR, Jena, Germany
- Faculty of Physics, Sofia University, Sofia, Bulgaria
| | - Stanislav Baluschev
- Faculty of Physics, Sofia University, Sofia, Bulgaria
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Wolfgang Sickenberger
- JenVis Research GbR, Jena, Germany
- Ernst Abbe University of Applied Sciences, Jena, Germany
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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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Walther H, Lorentz H, Heynen M, Kay L, Jones LW. The Impact of Incubation Conditions on In Vitro Phosphatidylcholine Deposition on Contact Lens Materials. Optom Vis Sci 2021; 98:341-349. [PMID: 33828039 DOI: 10.1097/opx.0000000000001680] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
SIGNIFICANCE Previous in vitro measurements of contact lenses commonly investigate the impact of nonpolar tear film lipids (i.e., sterols). Polar lipids, however, are equally important stabilizing components of the tear film. This research explores and presents further knowledge about various aspects of polar lipid uptake that may impact contact lens performance. PURPOSE This study evaluated the impact of incubation time, lipid concentration, and replenishment of an artificial tear solution (ATS) on the uptake of phosphatidylcholine (PC) onto conventional hydrogel (CH) and silicone hydrogel (SH) contact lens materials. METHODS Four SHs and two CH lens materials (n = 4) were soaked in a complex ATS containing radioactive 14C-PC as a probe molecule. Phosphatidylcholine uptake was monitored at various incubation time points (1, 3, 7, 14, and 28 days), with different ATS lipid concentrations (0.5×, 1×, 2×) and with and without regular replenishment of the ATS. Phosphatidylcholine was extracted from the lenses, processed, and counted by a β counter, and accumulated PC (μg/lens) was extrapolated from standard lipid calibration curves. RESULTS All materials exhibited increasing PC deposition over time. Conventional hydrogel materials showed significantly lower PC uptake rates (P < .001) than any of the SH materials. Increasing lipid concentration in the ATS resulted in increased PC binding onto the contact lens materials (P < .001). Replenishing the ATS every other day, however, impacted the PC deposition differently, showing increased binding (P < .001) on CHs and reduced PC deposition for SH materials (P < .001). CONCLUSIONS Length of incubation, lipid concentration in the ATS, and renewal of the incubation solution all influenced the amount of PC that sorbed onto various lens materials and therefore need to be considered when conducting future in vitro deposition studies.
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Affiliation(s)
| | | | - Miriam Heynen
- Centre for Ocular Research & Education, School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Lise Kay
- Centre for Ocular Research & Education, School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
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Phan CM, Walther H, Qiao H, Shinde R, Jones L. Development of an Eye Model With a Physiological Blink Mechanism. Transl Vis Sci Technol 2019; 8:1. [PMID: 31534830 PMCID: PMC6727780 DOI: 10.1167/tvst.8.5.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 07/04/2019] [Indexed: 01/26/2023] Open
Abstract
Purpose To develop an eye model with a physiological blink mechanism. Methods All parts of the eye model were designed using computer-aided design software. The eyelid consisted of a unique 3D printed structure containing teeth to physically secure a flexible membrane. Both the eyeball and eyelid membrane were synthesized using polyvinyl alcohol (PVA). Four molecular weights of PVA (89–98, 85–124, 130, and 146–186 kDa) were tested at a range of concentrations between 5% and 30% weight/volume. The wettability and water content of these materials were compared with the bovine cornea and sclera. The model was connected to a microfluidic pump, which delivers artificial tear solution (ATS) to the eyelid. A corneal topographer was used to evaluate the tear break-up and tear film regeneration. Results The eyelid flexes and slides across the eyeball during each blink, which ensures direct contact between the two surfaces. When loaded with an ATS, this mechanism evenly spreads the solution over the eyeball to generate an artificial tear film. The artificial tear film in this eye model had a tear break-up time (TBUT) of 5.13 ± 0.09 seconds at 1.4 μL/min flow rate, 6 blinks/min, and <25% humidity. Conclusions This model simulates a physiological blink actuation and an artificial tear film layer. Future studies will examine variations in flow rates and ATS composition to simulate clinical values of TBUT. Translational Relevance The eye model could be used to study in vitro TBUT, tear deposition, and simple drug delivery.
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Affiliation(s)
- Chau-Min Phan
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Hendri Walther
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Ha Qiao
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Ra Shinde
- Manipal Academy of Higher Education, Manipal Institute of Technology, Madhav Nagar, Manipal, Karnataka, India
| | - Lyndo Jones
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
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Naroo SA. BCLA conference delivers the key topics. Cont Lens Anterior Eye 2019; 42:339-340. [PMID: 31248820 DOI: 10.1016/j.clae.2019.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Shehzad A Naroo
- School of Life and Health Sciences, Ophthalmic Research Group, Aston University, Aston Street, Birmingham B4 7ET, United Kingdom.
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