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Peer-reviewed articles

2017

Regmi,S. C., Samsom,M. L., Heynen,M. L., Jay,G. D., Sullivan,B. D., Srinivasan,S., Caffery,B., Jones,L., Schmidt,T. A. Degradation of proteoglycan 4/lubricin by cathepsin S: Potential mechanism for diminished ocular surface lubrication in Sjögren's syndrome. Experimental eye research 2017;1611-9. [ Show Abstract ]

Sjögren's syndrome (SS) is an autoimmune disease affecting the lacrimal and salivary glands with hallmark clinical symptoms of dry eye and dry mouth. Recently, markedly increased cathepsin S (CTSS) activity has been observed in the tears of SS patients. Proteoglycan 4 (PRG4), also known as lubricin, is an effective boundary lubricant that is naturally present on the ocular surface. While PRG4 is susceptible to proteolytic digestion, the potential effect of CTSS on PRG4 remains unknown. The objective of this study was to assess the ability of CTSS to enzymatically degrade purified PRG4, and PRG4 naturally present in human tears, and alter ocular surface boundary lubricating properties. To assess the potential time course and dose-dependency of PRG4 digestion by CTSS, full-length recombinant human PRG4 (rhPRG4) was incubated at 37 °C with or without CTSS in an enzymatic digestion buffer. Digestion of PRG4 by CTSS was also examined within normal human tear samples, both with and without supplementation by rhPRG4. Finally, digestion of endogenous PRG4 by CTSS, and the effect of a CTSS inhibitor, was examined in SS tears on Schirmer strips. Digestion products were separated on 3–8% SDS-PAGE and visualized by protein staining and western blotting. The boundary lubricating ability of rhPRG4 samples was assessed using an in vitro human eyelid-cornea friction test. Finally, SDS-PAGE protein stain bands resulting from rhPRG4 digestion were submitted for tandem mass spectrometry analysis to confirm their identity as PRG4 and identify non-tryptic cleavage sites. CTSS digested rhPRG4 in a time and dose dependent manner. CTSS digestion of rhPRG4 at 1% (where % is the mass ratio of CTSS to rhPRG4) resulted in a time dependent decrease in the full-length, ~460 kDa, monomeric rhPRG4 band, and an appearance of lower MW fragments. After 20 h, no full-length rhPRG4 was observed. Furthermore, with an increased relative enzyme concentration of 3%, no protein bands were observed after 2 h, indicating complete digestion of rhPRG4. Western blotting demonstrated PRG4 is present in normal human tears, and that rhPRG4, tears, and tears supplemented with rhPRG4 incubated with 3–9% CTSS demonstrated decreased intensity of high MW PRG4 bands, indicative of partial degradation by CTSS. Similarly, western blotting of PRG4 in SS tears incubated with CTSS demonstrated decreased intensity of high MW PRG4 bands, which was reversed in the presence of the CTSS inhibitor. CTSS treatment of rhPRG4 resulted in an increased friction coefficient, compared to untreated controls. Lastly, the lower MW bands were confirmed to be PRG4 fragments by tandem mass spectrometry, and 6 non-tryptic cleavage sites were identified. rhPRG4 is susceptible to proteolytic digestion by CTSS, both alone and in human tears, which results in diminished ocular surface boundary lubricating ability. Moreover, endogenous PRG4 is susceptible to proteolytic digestion by CTSS, both in normal and SS tears. Given the elevated activity of CTSS in SS tears, and the role intact PRG4 plays in ocular surface health and lubrication, degradation of PRG4 by CTSS is a potential mechanism for diminished ocular surface lubrication in SS. Collectively these results suggest that tear supplementation of PRG4 may be beneficial for SS patients. © 2017 Elsevier Ltd

Heynen,M., Babaei Omali,N., Fadli,Z., Coles-Brennan,C., Subbaraman,L. N., Jones,L. Selectivity and localization of lysozyme uptake in contemporary hydrogel contact lens materials. Journal of Biomaterials Science, Polymer Edition 2017;28,13:1351-1364. [ Show Abstract ]

The purpose of this study was to investigate the early and selective uptake of lysozyme and the location of deposited lysozyme on contemporary hydrogel contact lens (CL) materials after exposure to an artificial tear solution (ATS) for 16 h. Seven different hydrogel CL materials [polymacon, omafilcon A, nelfilcon A, nesofilcon A, ocufilcon B, etafilcon A (Acuvue Moist), and etafilcon A (Acuvue Define)] were incubated in an ATS for various times. Total protein deposition was determined using a modified Bradford technique. Lysozyme, lactoferrin, and albumin deposition on CLs were determined using 125I-radiolabeling method. A confocal laser scanning microscopy (CLSM) technique was utilized to map the location of lysozyme uptake in an asymmetric environment. All lens materials had significant amounts of lysozyme after 1 min of exposure to ATS. After 16 h of incubation, higher levels of total protein deposited on the two etafilcon A-based lenses (Moist and Define), followed by ocufilcon B and both were significantly higher than all other CLs tested (p = 0.0001). The two etafilcon A materials (Moist and Define) also deposited the highest amounts of lysozyme (514.8 ± 28.4 and 527.1 ± 14.7 µg/lens respectively) when compared to other test CLs (p = 0.0001). The CLSM technique revealed that the non-ionic CLs tended to have symmetric distribution of lysozyme throughout the lens materials, while the ionic CLs had an asymmetric distribution, with the highest concentration of lysozyme on and near the exposed surface. The quantity and nature of proteins deposited on CLs varies, depending upon the chemical composition of the material. Among the various lenses tested, etafilcon A deposited the highest amount of total protein, most of it represented by lysozyme, which was largely located near the surface of the lens. © 2017 Informa UK Limited, trading as Taylor & Francis Group.

2016

Hall,B., Heynen,M., Jones,L. W., Forrest,J. A. Analysis of Using I125 Radiolabeling for Quantifying Protein on Contact Lenses. Current eye research 2016;41,4:456-465. [ Show Abstract ]

Purpose: To investigate the accuracy of I125 radiolabeling to quantitatively determine the deposition of protein onto various commercially available contact lens (CL) materials. Methods: Commercially available silicone hydrogel and conventional hydrogel CL materials were examined for times ranging from 10 s to 1 week. Adsorption of free I125 was measured directly for the CL. The use of dialyzing labeled proteins and/or using NaI to compete with free I125 uptake was investigated as ways to minimize effects due to free I125. Results: At all time points and with all lens materials, there was 0.3 µg/lens or greater of apparent mass attributable to free I125 uptake. Dialyzing labeled proteins significantly reduced free I125 uptake for all materials investigated. The benefit of using dialyzed protein was most prominent at shorter times, as free I125 is continuously generated over time. Using NaI can reduce free I125 uptake for some lens materials, but this is shown to directly affect protein deposition on some materials. Conclusions: Periodic replenishment of incubation solutions with freshly dialyzed labeled protein to limit free I125 generation is recommended, but the incorporation of NaI onto the buffer solution is not. Irrespective of the exact procedure to limit free I125 uptake, extra steps must be performed to quantify the amount of I125 adsorbed onto contact lens materials, to determine thresholds of confidence with respect to the actual protein deposition that occurs.

Omali,N. B., Heynen,M., Subbaraman,L. N., Papinski,D., Lakkis,C., Smith,S. L., Morgan,P. B., Berntsen,D. A., Nichols,J. J., Jones,L. W., Mathew,J. H., Cox,S. M., Bickle,K. M., Powell,D. R., Cox,J., Miller,W. L., Wallace-Tucker,A., Charrier,S., Chen,Y. -J, Cardenas,L., Huerta,S., Dionne,K., Maldonado-Codina,C., Plowright,A. J., Howarth,G. F., Chatterjee,N., Mirza,A., Dumbleton,K., Schulze,M., Moezzi,A. M., Luensmann,D., Ngo,W., Paquette,L., Srinivasan,S., Varikooty,J., Johnson,J., Simpson,M., Vos Impact of lens care solutions on protein deposition on soft contact lenses. Optometry and Vision Science 2016;93,8:963-972. [ Show Abstract ]

Purpose. To evaluate the effect of four contemporary lens care solutions on total protein, total lysozyme, and active lysozyme extracted from three contact lens materials. Methods. Adapted contact lens wearers were recruited at three sites, and all subjects were randomly assigned to daily wear of either etafilcon A, galyfilcon A, or senofilcon A for 2 weeks. Four lens care solutions (Biotrue, OPTI-FREE PureMoist, RevitaLens OcuTec, and ClearCare) were used by each subject in random order with a new pair of lenses after a washout period between solutions of at least 4 days. After 2 weeks of daily wear, contact lenses were collected for analysis. Proteins were extracted from a subset of contact lenses (n = 568) and total protein, total lysozyme, and lysozyme activity were quantified using a modified Bradford assay, an enzyme-linked immunosorbent assay, and a micrococcal assay, respectively. Results. Higher levels of total protein were extracted from etafilcon A when used with Biotrue compared to other solutions (p = 0.0001). There were higher levels of total lysozyme extracted from galyfilcon A lenses when used with PureMoist than with Biotrue or Clear Care (p < 0.006). Higher total lysozyme was extracted from senofilcon A when used with RevitaLens OcuTec compared to Biotrue (p = 0.002). Lower lysozyme activity was recovered from senofilcon A lenses with RevitaLens OcuTec when compared to all other care solutions (all p < 0.004). When Biotrue, PureMoist, or RevitaLens OcuTec were used, higher total lysozyme was extracted from galyfilcon A compared to senofilcon A(p < 0.01). When RevitaLens OcuTec was used, higher levels of active lysozyme were extracted from galyfilcon A compared to senofilcon A (p = 0.02). Conclusions. The ability of lens care solutions to remove protein from lenses varies depending upon the care solution composition and also the polymeric make-up of the contact lens material. © Copyright 2016 American Academy of Optometry.

2014

Caffery,B. E., Joyce,E., Heynen,M. L., Ritter,R., Jones,L. A., Senchyna,M. Quantification of conjunctival TNF-a in aqueous-deficient dry eye. Optometry and Vision Science 2014;91,2:156-162. [ Show Abstract ]

PURPOSE: This study aimed to quantify and compare conjunctival epithelial tumor necrosis factor (NF) a mRNA expression in Sjögren syndrome (SS), non-Sjögren syndrome aqueous-deficient dry eye (non-SS DE), and non-dry eye (NDE) control subjects. METHODS: A total of 76 subjects were recruited for this study: 25 SS (confirmed via American-European Consensus Criteria 2002), 25 non-SS DE (confirmed by symptoms and Schirmer scores = 10 mm), and 26 NDE. Superior and temporal bulbar conjunctival epithelial cells were collected via impression cytology. Epithelial RNA was extracted, and TNF-a mRNA expression was quantified by real-time quantitative polymerase chain reaction. RESULTS: The expression of TNF-a mRNA was found to be significantly higher in the SS group (2.48 ± 1.79) compared to both non-SS DE (0.95 ± 1.18; p < 0.05) and NDE (0.84 ± 0.51; p < 0.05) groups. No difference in TNF-a mRNA expression was found between the non-SS DE and NDE groups (p = 0.67). CONCLUSIONS: These results demonstrate that SS-associated aqueous-deficient dry eye is associated with a significant upregulation of conjunctival epithelial TNF-a mRNA relative to both non-SS DE and control groups. The degree to which TNF-a mRNA is upregulated in SS may contribute to the severe ocular surface damage observed in these patients. Copyright © 2014 American Academy of Optometry.

2013

Ng,A., Heynen,M., Luensmann,D., Subbaraman,L. N., Jones,L. Impact of tear film components on the conformational state of lysozyme deposited on contact lenses. Journal of Biomedical Materials Research - Part B Applied Biomaterials 2013;101,7:1172-1181. [ Show Abstract ]

Purpose To investigate the impact of lactoferrin and lipids on the kinetic denaturation of lysozyme deposited on silicone and conventional hydrogel lenses, using a complex artificial tear solution (ATS). Methods Two silicone hydrogel lenses (AIR OPTIX AQUA; lotrafilcon B and ACUVUE OASYS; senofilcon A) and two conventional hydrogel lenses (ACUVUE 2; etafilcon A and PROCLEAR; omafilcon A) were incubated in four solutions: an ATS, ATS without lactoferrin, ATS without lipids, and ATS without lactoferrin and lipids. At various time points over a 28-day period, the percentage of active lysozyme per lens was determined using a fluorescence activity assay and an ELISA. Results After 28 days, the percentage of active lysozyme extracted from etafilcon A lenses in all solutions was significantly higher than all other lens materials (p 0.05). The inclusion of lipids in the ATS significantly increased the lysozyme denaturation on both silicone hydrogel materials (p 0.05). The inclusion of lipids in the ATS significantly increased the lysozyme denaturation on both silicone hydrogel materials (p 0.05). Conclusions Lactoferrin and lipids have an impact on the denaturation of lysozyme deposited onto silicone hydrogel contact lenses, while conventional hydrogel lenses were unaffected. Future in vitro studies should consider the impact of tear film components when investigating protein deposition and denaturation on contact lenses. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 1172-1181, 2013. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

Ng,A., Heynen,M., Luensmann,D., Subbaraman,L. N., Jones,L. Optimization of a fluorescence-based lysozyme activity assay for contact lens studies. Current eye research 2013;38,2:252-259. [ Show Abstract ]

Purpose: To optimize a fluorescence-based lysozyme activity assay to investigate the conformational state of lysozyme in solution and to determine the impact of extraction and evaporation procedures and the possible interference of contact lens materials on lysozyme activity. Methods: The fluorescence-based lysozyme activity assay, Enzchek (Molecular Probes Inc, Eugene, OR) which utilizes fluorescently quenched Micrococcus lysodeikticus, was compared to the gold standard, classical lysozyme turbidity assay, using four differently concentrated lysozyme samples (20, 10, 5.0 and 2.0 ng/µL). Furthermore, six differently concentrated lysozyme samples (2.0, 1.0, 0.5, 0.25, 0.125 and 0.01 µg/µL) were quantified using the fluorescence-based assay in the presence of extraction solvents consisting of 0.2% and 0.02% trifluroacetic acid/acetonitrile and following evaporation procedures. Results: A standard curve was generated by the fluorescence-based assay ranging from 2 to 150 ng. The total active lysozyme quantified in the four lysozyme samples was not significantly different between the two assays (p > 0.05) and the concordance correlation coefficient was determined to be 0.995. However an average discrepancy between the two assays was found to be 0.474 ng, with the turbidity assay typically reporting higher active lysozyme measurements. The sensitivity of the fluorescence-based assay was higher than the classical turbidity assay when quantifying 20 ng or less active lysozyme. Following the extraction and evaporation procedures and the addition of lens extracts, the total active lysozyme recovered was 95% or greater. Conclusions: In comparison to the classical turbidity assay, the fluorescence-based assay is a very sensitive method, making it a favorable technique, particularly when studying contact lens materials that deposit relatively low levels of lysozyme. © Informa Healthcare USA, Inc.

Srinivasan,S., Heynen,M. L., Martell,E., Ritter III,R., Jones,L., Senchyna,M. Quantification of MUCIN 1, cell surface associated and MUCIN16, cell surface associated proteins in tears and conjunctival epithelial cells collected from postmenopausal women. Molecular Vision 2013;19970-979. [ Show Abstract ]

Purpose: To quantify the expression of mucin 1, cell surface associated (MUC1) and mucin 16, cell surface associated (MUC16) proteins and messenger ribonucleic acid (mRNA) in a cohort of postmenopausal women (PMW), to explore the relationship between mucin expression, dry eye symptomology, and tear stability. Methods: Thirty-nine healthy PMW (>50 years of age) were enrolled in this study. No specific inclusion criteria were used to define dry eye; instead, a range of subjects were recruited based on responses to the Allergan Ocular Surface Disease Index (OSDI) questionnaire and tear stability measurements as assessed by non-invasive tear breakup time (NITBUT). Tears were collected from the inferior tear meniscus using a disposable glass capillary tube, and total RNA and total protein were isolated from conjunctival epithelial cells collected via impression cytology. Expression of membrane-bound and soluble MUC1 and MUC16 were quantified with western blotting, and expression of MUC1 and MUC16 mRNA was assessed with real-time PCR. Results: OSDI responses ranged from 0 to 60, and NITBUT ranged from 18.5 to 2.9 s. Only two statistically significant correlations were found: soluble MUC16 protein concentration and MUC16 mRNA expression with OSDI vision related (-0.47; p=0.01) and ocular symptom (0.39; p=0.02) subscores, respectively. Post hoc exploratory analysis on absolute expression values was performed on two subsets of subjects defined as asymptomatic (OSDI =6, n=12) and moderate to severe symptomatic (OSDI =20, n=12). The only significant difference between the two subgroups was a significant reduction in MUC16 mRNA expression found in the symptomatic dry eye group (1.52±1.19 versus 0.57±0.44; p=0.03). Conclusions: A broad exploration of mucin expression compared to either a sign (NITBUT) or symptoms of dry eye failed to reveal compelling evidence supporting a significant relationship, other than a potential association between MUC16 with specific symptoms. Furthermore, comparison of mucin protein and expression levels between the asymptomatic and moderate to severe symptomatic subgroups revealed only one significant difference, a reduction in MUC16 mRNA expression in the symptomatic subgroup. © 2013 Molecular Vision.

Walther,H., Lorentz,H., Heynen,M., Kay,L., Jones,L. W. Factors that influence in vitro cholesterol deposition on contact lenses. Optometry and Vision Science 2013;90,10:1057-1065. [ Show Abstract ]

PURPOSE: The purpose of this study was to analyze the impact that incubation time, lipid concentration, and solution replenishment have on silicone hydrogel (SiHy) and conventional hydrogel (CH) contact lens cholesterol deposition via in vitro radiochemical experiments. METHODS: Four SiHy (senofilcon A, lotrafilcon B, comfilcon A, balafilcon A) and two CH (etafilcon A and omafilcon A) contact lenses were incubated in an artificial tear solution (ATS) that contained major tear film proteins, lipids, salts, salts, and a trace amount of radioactive C-cholesterol. Lenses were incubated for various incubation times (1, 3, 7, 14, or 28 days), with three concentrations of lipid (0.5×, 1×, 2× tear film concentration) and with or without solution replenishment to assess each variable's impact on cholesterol deposition. After incubation, the lenses were extracted using 2:1 chloroform:methanol, extracts were analyzed in a beta counter and masses (micrograms per lens) were extrapolated from standard curves. RESULTS: Within the SiHy materials, balafilcon A deposited the greatest amount of cholesterol (p replenishing > 1× > 0.5×. CONCLUSIONS: Overall, SiHy lenses deposit significantly more cholesterol than CH lens materials, and the mass of lipid deposited is dependent on the contact lens material, length of incubation, concentration of lipids in the ATS, and the replenishment of ATS. Copyright © 2013 American Academy of Optometry.

2012

Jadi,S., Heynen,M., Luensmann,D., Jones,L. Composition of incubation solution impacts in vitro protein uptake to silicone hydrogel contact lenses. Molecular Vision 2012;18337-347. [ Show Abstract ]

Purpose: To determine the impact of incubation solution composition on protein deposition to silicone hydrogel (SH) contact lenses using a simplistic and a complex model of the tear film. Methods: Three SH materials - senofilcon A (SA), lotrafilcon B (LB), and balafilcon A (BA) - were incubated in two different solutions; Solution A was a simplistic augmented buffered saline solution containing a single protein, whereas Solution B was a complex artificial tear solution (ATS), containing the augmented buffered saline solution in addition to proteins, lipids, and mucins (pH=7.4). The proteins of interest (lysozyme, lactoferrin, albumin) were radiolabeled with Iodine-125 (2% protein of interest) and the accumulation of the conjugated protein to the lens materials was determined after 1, 7, 14, and 28 days of incubation. Protein deposition was measured using a gamma counter and the raw data were translated into absolute amounts (μg/lens) via extrapolation from standards. Results: After 28 days, lysozyme uptake was significantly lower on BA lenses when incubated in Solution A (33.7 μg) compared to Solution B (56.2 μg), p0.05. LB lenses also deposited similar amounts of lysozyme for both solutions (Solution A: 5.0 μg, Solution B: 4.7 μg, p>0.05). After 28 days, BA lenses accumulated approximately twice the amount of lactoferrin than the other lens materials, with 30.3 μg depositing when exposed to Solution A and 22.0 μg with Solution B. The difference between the two solutions was statistically significant (p0.05. LB lenses also deposited similar amounts of lysozyme for both solutions (Solution A: 5.0 μg, Solution B: 4.7 μg, p>0.05). After 28 days, BA lenses accumulated approximately twice the amount of lactoferrin than the other lens materials, with 30.3 μg depositing when exposed to Solution A and 22.0 μg with Solution B. The difference between the two solutions was statistically significant (p0.05). After 28 days, albumin deposition onto BA lenses was significantly greater when lenses were incubated in Solution B (1.7 μg) compared to Solution A (0.9 μg), p0.05). LB lenses incubated in Solution A deposited more albumin compared to Solution B (0.9 μg versus 0.6 μg), p=0.003. Discussion: Protein deposition onto SH materials varied when contact lenses were incubated in either a complex ATS compared to a single protein solution. More lysozyme accumulated onto BA lenses incubated in a complex analog of the human tear film, whereas lactoferrin deposited onto SA lenses independent of incubation solution composition. To better mimic the ex vivo environment, future studies should use more appropriate analogs of the tear film. © 2012 Molecular Vision.

Lorentz,H., Heynen,M., Khan,W., Trieu,D., Jones,L. The impact of intermittent air exposure on lipid deposition. Optometry and Vision Science 2012;89,11:1574-1581. [ Show Abstract ]

PURPOSE: To analyze the impact of intermittent air exposure on the in vitro deposition of two radioactive lipids on various contact lens (CL) materials, using a custom-designed model blink cell. METHODS: Six different CL materials (balafilcon A, lotrafilcon B, comfilcon A, senofilcon A, etafilcon A, and omafilcon A) were mounted on the model blink cell pistons, which cycled the lenses in and out of a complex artificial tear solution (ATS) that contained a trace amount of C-cholesterol or C-phosphatidylcholine. For the short-term experiment, air-exposed lenses were continuously cycled in and out of the ATS for 10 h. Longer term incubations for 6 days were tested with lotrafilcon B and balafilcon A materials incubated in C-cholesterol ATS. The air-exposed CLs were cycled for 14 h then submerged for 10 h each day. For both experiments, the control lenses were submerged for the entire test period. After incubation, lenses were processed, and deposited masses were quantified. RESULTS: Exposure to air resulted in increased amounts of cholesterol deposited by 1.6 to 4.3 fold on omafilcon A, balafilcon A, comfilcon A, and senofilcon A (p ≤ 0.03) compared with submerged lenses. No differences in deposition were observed for etafilcon A and lotrafilcon B (p > 0.05). The longer term incubation of lotrafilcon B and balafilcon A showed statistically significant increases in cholesterol deposition for both air-exposed lens materials (p 0.05). CONCLUSIONS: This study found that lipid deposition profiles are CL material dependent and that intermittent air exposure can influence the mass of lipid deposited. Copyright © 2012 American Academy of Optometry.

Lorentz,H., Heynen,M., Tran,H., Jones,L. Using an in vitro model of lipid deposition to assess the efficiency of hydrogen peroxide solutions to remove lipid from various contact lens materials. Current eye research 2012;37,9:777-786. [ Show Abstract ]

Purpose: To test the ability of two commercially available hydrogen peroxide disinfection solutions, one containing a surfactant and one without, to remove lipid from various contact lens materials using in vitro radiochemical experiments. Methods: Etafilcon A, senofilcon A and balafilcon A contact lens materials were incubated in an artificial tear solution (ATS) containing a mixture of lipids, proteins, mucin and either 14C-cholesterol or 14C-phosphatidylcholine for 8 h. Following incubation, the lenses were removed, rinsed, and placed for 16 h in either a surfactant-containing peroxide solution (ClearCare ®), a peroxide solution devoid of a surfactant (AOSept ®) or stored without solution (control). This process was repeated every day for 1 week. The lenses were extracted with a previously optimized extraction protocol, evaporated, re-suspended, fluor added and counted for their radioactive signals. Masses of lipids deposited were calculated based on standard calibration curves, the disinfection solutions were compared and repeated measures ANOVA and post hoc statistical analysis was completed using Statistica 9. Results: The results of this experiment found that daily disinfection with hydrogen peroxide solutions reduced the amount of cholesterol and phosphatidylcholine deposited on the three contact lens materials examined, however in many cases the reduction in deposition was less than 15% when compared to the control. Disinfection with the solution containing the surfactant (ClearCare), resulted in the least deposited cholesterol and phosphatidylcholine for all materials, however not all of the comparisons were statistically significant. Conclusions: Overall, ClearCare hydrogen peroxide disinfection solution containing Pluronic 17R4 removed the most lipid from lenses when compared to the non-surfactant containing AOSept or the control, for both lipids and all lens materials. However, the differences found were quite small at times and whether these differences are clinically significant are yet to be determined. © 2012 Informa Healthcare USA, Inc.

Lorentz,H., Heynen,M., Trieu,D., Hagedorn,S. J., Jones,L. The impact of tear film components on in vitro lipid uptake. Optometry and Vision Science 2012;89,6:856-867. [ Show Abstract ]

Purpose. To analyze the influence of various tear film components on in vitro deposition of two lipids (cholesterol and phosphatidylcholine) on three contact lens materials. Methods. Etafilcon A, balafilcon A, and senofilcon A were incubated in four different incubation solutions for 3 or 14 days: an artificial tear solution containing lipids and proteins, a protein tear solution containing proteins and the lipid of interest, a lipid tear solution containing lipids and no proteins, and a single lipid tear solution containing the lipid of interest only. Each incubation solution contained one of the two radiolabeled lipids: C-cholesterol (C) or C-phosphatidylcholine (PC). After soaking, lenses were removed from the incubation solution, the lipids were extracted and quantified using a beta counter, and masses of lipid were calculated using standard calibration curves. Results. This experiment examined several different parameters influencing lipid deposition on contact lenses, including lens material, length of incubation, and the composition of the incubation solution. Overall, lipid deposited differently on different lens materials (p senofilcon > etafilcon. Incubation solution had a large impact on how much lipid was deposited (p < 0.00001), although cholesterol and phosphatidylcholine demonstrated different deposition patterns. Lipid deposition after 14 days of incubation was consistently greater than after 3 days (p < 0.02). Conclusions. This in vitro study demonstrates that C and PC deposition are cumulative over time and that silicone hydrogel materials deposit more lipid than group IV conventional hydrogel materials. It also clearly demonstrates that deposition of C and PC is influenced by the composition of the incubation solution and that in vitro models must use more physiologically relevant incubation solutions that mimic the natural tear film if in vitro data is to be extrapolated to the in vivo situation. © 2012 American Academy of Optometry.

Ng,A., Heynen,M., Luensmann,D., Jones,L. Impact of tear film components on lysozyme deposition to contact lenses. Optometry and Vision Science 2012. [ Show Abstract ]

PURPOSE: To investigate the impact of lactoferrin and lipids on the kinetic deposition of lysozyme on silicone and conventional hydrogel lenses, using a complex artificial tear solution (ATS). METHODS: Two silicone hydrogel lenses (AIR OPTIX AQUA; lotrafilcon B and ACUVUE OASYS; senofilcon A) and two conventional hydrogel lenses (ACUVUE 2; etafilcon A and PROCLEAR; omafilcon A) were investigated. Lenses were incubated in four different solutions: a complex ATS consisting of various salts, lipids, proteins, and mucins, an ATS without lactoferrin (ATS w/o Lac), an ATS without lipids (ATS w/o Lip), and an ATS without lactoferrin and lipids (ATS w/o Lac & Lip), each containing 2% radiolabeled (125I) lysozyme (1.9 mg/ml). After each time point (4, 12 h and 1, 2, 3, 5, 7, 14, 21, 28 days), the amount of lysozyme per lens was quantified. RESULTS: After 28 days, lotrafilcon B lenses incubated in ATS deposited significantly less lysozyme (9.7 ± 1.4 μg) than when incubated in solutions not containing lactoferrin and lipids (more than 11.8 μg) (p < 0.001). Lysozyme uptake to senofilcon A lenses was higher in ATS w/o Lip (5.3 ± 0.1 μg) compared with other solutions (less than 3.9 μg) (p < 0.001). Etafilcon A lenses deposited the most lysozyme in all four solutions compared with the rest of the lens types (p < 0.001). For etafilcon A lenses, less lysozyme was deposited when incubated in ATS w/o Lip (588.6 ± 0.4 μg) compared with the other solutions (more than 642.6 μg) (p < 0.001). Omafilcon A lenses in ATS w/o Lac accumulated significantly less lysozyme (12.8 ± 1.0 μg) compared with the other solutions (more than 14.2 μg) (p < 0.001). CONCLUSIONS: An ATS containing lactoferrin and lipids impacts lysozyme deposition on both silicone and conventional hydrogel contact lenses. When performing in vitro experiments to study protein deposition on contact lenses, more complex models should be used to better mimic the human tear film.

2011

Heynen,M., Lorentz,H., Srinivasan,S., Jones,L. Quantification of non-polar lipid deposits on senofilcon A contact lenses. Optometry and Vision Science 2011;88,10:1172-1179.

Lorentz,H., Heynen,M., Kay,L. M. M., Dominici,C. Y., Khan,W., Ng,W. W. S., Jones,L. Contact lens physical properties and lipid deposition in a novel characterized artificial tear solution. Molecular Vision 2011;173392-3405. [ Show Abstract ]

Purpose: To characterize various properties of a physiologically-relevant artificial tear solution (ATS) containing a range of tear film components within a complex salt solution, and to measure contact lens parameters and lipid deposition of a variety of contact lens materials after incubation in this ATS. Methods: A complex ATS was developed that contains a range of salts, proteins, lipids, mucin, and other tear film constituents in tear-film relevant concentrations. This ATS was tested to confirm that its pH, osmolality, surface tension, and homogeneity are similar to human tears and remain so throughout the material incubation process, for up to 4 weeks. To confirm that silicone hydrogel and conventional hydrogel contact lens materials do not alter in physical characteristics beyond what is allowed by the International Organization for Standardization (ISO) 18369-2. The diameter, center thickness, and calculated base curve were measured for five different lens materials directly out of the blister pack, after a rinse in saline and then following a two week incubation in the modified ATS. To test the ATS and the effect of its composition on lipid deposition, two lens materials were incubated in the ATS and a modified version for several time points. Both ATS solutions contained trace amounts of carbon-14 cholesterol and phosphatidylcholine, such that deposition of these specific lipids could be quantified using standard methods. Results: This ATS is a complex mixture that remains stable at physiologically relevant pH (7.3-7.6), osmolality (304- 306 mmol/kg), surface tension (40-46 dynes/cm) and homogeneity over an incubation period of three weeks or more. The physical parameters of the lenses tested showed no changes beyond that allowed by the ISO guidelines. Incubations with the ATS found that balafilcon A lenses deposit significantly more cholesterol and phosphatidylcholine than omafilcon A lenses (p<0.05) and that removing lactoferrin and immunoglobulin G from the ATS can significantly decrease the mass of lipid deposited. Conclusions: This paper describes a novel complex artificial tear solution specially designed for in-vial incubation of contact lens materials. This solution was stable and did not adversely affect the physical parameters of the soft contact lenses incubated within it and showed that lipid deposition was responsive to changes in ATS composition. © 2011 Molecular Vision.

2010

Boone,A., Heynen,M., Joyce,E., Jones,L. Ex vivo protein deposition on bi-weekly silicone hydrogel contact lenses. Optometry and Vision Science 2010;87,2:146.

Caffery,B., Heynen,M. L., Joyce,E., Jones,L., Robert III,R., Senchyna,M. MUC1 expression in Sjogren's syndrome, KCS, and control subjects. Molecular Vision 2010;161720-1727. [ Show Abstract ]

Purpose: To quantify and compare human mucin 1 (MUC1) protein and mRNA expression in tears and conjunctival epithelial cells collected from Sjogren's syndrome (SS), non-Sjogren's keratoconjunctivitus sicca (KCS) and non-dry eyed (NDE) control subjects. Methods: Seventy-six subjects were recruited for this study: 25 SS (confirmed via American-European Consensus Criteria 2002), 25 KCS (confirmed by symptoms and Schirmer scores ≤10 mm) and 26 NDE. Tears were collected using an eyewash technique. Impression cytology was used to gather protein and mRNA from conjunctival epithelial cells. Soluble and membrane bound MUC1 were quantified via western blotting and MUC1 mRNA was quantified by real time qPCR. Results: The SS group demonstrated significantly higher concentrations of soluble MUC1 (0.12±0.11 [SS]; 0.013±0.02 [KCS; p=0.001]; 0.0023±0.0024 [NDE; p<0.001]) and MUC1 mRNA (3.18±1.44 [SS]; 1.79±1.18 [KCS; p<0.05]; 1.60±0.74 [NDE; p<0.05]) compared to both KCS and NDE groups. Soluble MUC1 expression was also higher in the KCS group compared to the NDE group (p=0.02), where as MUC1 mRNA expression was similar in both KCS and NDE groups. Membrane bound MUC1 expression differed only between the SS and NDE groups (0.005±-0.003 [SS]; 0.003±0.002 [NDE; p=0.002]). Conclusions: These results demonstrate that SS subjects express greater quantities of MUC1 protein and mRNA compared to both KCS and control subjects. Increased soluble MUC1 expression was also found in KCS subjects compared to controls. Membrane bound MUC1 was present in higher concentration in SS versus NDE only. These significant changes in MUC1 expression may represent compensatory or protective responses to chronic insult to the ocular surface. © 2010 Molecular Vision.

Luensmann,D., Heynen,M., Liu,L., Sheardown,H., Jones,L. The efficiency of contact lens care regimens on protein removal from hydrogel and silicone hydrogel lenses. Molecular Vision 2010;16,10-11:79-92. [ Show Abstract ]

Purpose: To investigate the efficiency of lysozyme and albumin removal from silicone hydrogel and conventional contact lenses, using a polyhexamethylene biguanide multipurpose solution (MPS) in a soaking or rubbing/soaking application and a hydrogen peroxide system (H2O2). Methods: Etafilcon A, lotrafilcon B and balafilcon A materials were incubated in protein solutions for up to 14 days. Lenses were either placed in radiolabeled protein to quantify the amount deposited or in fluorescent-conjugated protein to identify its location, using confocal laser scanning microscopy (CLSM). Lenses were either rinsed with PBS or soaked overnight in H2O2 or MPS with and without lens rubbing. Results: After 14 days lysozyme was highest on etafilcon A (2,200 μg) >balafilcon A (50 μg) >lotrafilcon B (9.7 μg) and albumin was highest on balafilcon A (1.9 μg) =lotrafilcon B (1.8 μg) >etafilcon A (0.2 μg). Lysozyme removal was greatest for balafilcon A >etafilcon A >lotrafilcon B, with etafilcon A showing the most change in protein distribution. Albumin removal was highest from etafilcon A >balafilcon A >lotrafilcon B. H2O2 exhibited greater lysozyme removal from etafilcon A compared to both MPS procedures (p0.62). Albumin removal was solely material specific, while all care regimens performed to a similar degree (p>0.69). Conclusions: Protein removal efficiency for the regimens evaluated depended on the lens material and protein type. Overall, lens rubbing with MPS before soaking did not reduce the protein content on the lenses compared to nonrubbed lenses (p=0.89). © 2010 Molecular Vision.

2009

Boone,A., Heynen,M., Joyce,E., Varikooty,J., Jones,L. Ex vivo protein deposition on bi-weekly silicone hydrogel contact lenses. Optometry and Vision Science 2009;86,11:1241-1249. [ Show Abstract ]

Purpose. This study investigated the protein deposition that occurs on daily wear silicone hydrogel (SH) lenses, after 2 weeks of wear. Methods. A total of 40 subjects were divided into equal groups, based on their habitual SH contact lens [CIBA Vision O2OPTIX (O2); Johnson & Johnson ACUVUE ADVANCE with HYDRACLEAR (ADV); Bausch & Lomb PureVision (PV); CIBA Vision Night & Day (ND)]. A randomized, double-masked, cross-over study was conducted in which subjects wore either their habitual SH material or Johnson & Johnson ACUVUE OASYS with HYDRACLEAR PLUS (OAS) for 2 weeks. At the end of the 2-week period, lenses were collected for analysis of total protein, total lysozyme, and percent denatured lysozyme. Results. Total protein was greatest for PV (33 ± 6 μg/lens), with other lenses depositing 0.05). Total lysozyme was also greatest for the PV lens (11 ± 3 μg/lens), with other lenses depositing 0.05). Total lysozyme was also greatest for the PV lens (11 ± 3 μg/lens), with other lenses depositing 0.05). Total lysozyme was also greatest for the PV lens (11 ± 3 μg/lens), with other lenses depositing 0.05). The percentage of lysozyme that was denatured was greatest for ND (90 ± 8%) and lowest for PV (23 ± 10%). The lysozyme extracted from ND and O2 lenses was significantly more denatured than that extracted from the other lens materials (p 0.05) or between ADV, OAS, and PV (p > 0.05). The amount of denatured lysozyme/lens was <3 μg/lens for all materials. Lysozyme as a percentage of the total protein deposited ranged from 32 (PV) to 6% (O2). Conclusions. This study confirms that all SH lenses deposit low levels of protein, and that the amount and percentage of denatured lysozyme can vary, depending on the overall surface charge of the material and absence or type of surface treatment. © 2009 American Academy of Optometry.

Luensmann,D., Heynen,M., Liu,L., Sheardown,H., Jones,L. Determination of albumin sorption to intraocular lenses by radiolabeling and confocal laser scanning microscopy. Journal of cataract and refractive surgery 2009;35,11:2000-2007. [ Show Abstract ]

Purpose: To determine albumin adsorption profiles and penetration depth of 3 intraocular lens (IOL) materials over time using confocal laser scanning microscopy (CLSM) and radiolabeling. Setting: Centre for Contact Lens Research, School of Optometry, and Department of Biology, University of Waterloo, Waterloo, Ontario, Canada. Methods: Poly(methyl methacrylate) (PMMA), silicone, and foldable hydrophilic acrylic IOLs were incubated in 0.5 mg/mL bovine serum albumin (BSA) for 1, 7, and 14 days. The BSA was conjugated with lucifer yellow VS to allow identification of the protein location by fluorescent imaging with CLSM. Next, the protein uptake was quantified using 2% 125I-labeled BSA. Results: Confocal laser scanning microscopy showed increasing BSA uptake for silicone and PMMA IOLs after 14 days of incubation (P<.05), with an apparent penetration depth of 8.7 μm ± 1.9 (SD) and 9.2 ± 1.4 μm, respectively. For hydrophilic acrylic IOLs, BSA was detected at a depth of 38 ± 7.4 μm after 1 day, followed by an increase to 192.7 ± 16.2 μm after 14 days. Despite the penetration depth into the hydrophilic acrylic IOLs, quantitative results confirmed that PMMA and hydrophilic acrylic deposited significantly less BSA (mean 278.3 ± 41.7 ng and 296.5 ± 33.1 ng, respectively) than silicone IOLs (mean 392.6 ± 37.6 ng) (P<.05). Conclusions: Silicone and PMMA IOL materials showed BSA sorption near the lens surface only, while BSA penetrated deep into the hydrophilic acrylic IOL matrix. Combining the qualitative CLSM method and quantitative radiolabeling technique provided detailed information on protein interactions with implantable biomaterials. © 2009 ASCRS and ESCRS.

Ngo,W., Heynen,M., Joyce,E., Jones,L. Impact of protein and lipid on neutralization times of hydrogen peroxide care regimens. Eye and Contact Lens 2009;35,6:282-286. [ Show Abstract ]

Purpose: To investigate the effect of protein, lipid, and lens material on the neutralization kinetics of one-step hydrogen peroxide disinfection systems. Methods: A UV-based assay was used to determine the rate of neutralization of three one-step hydrogen peroxide systems (CIBA Vision Clear Care; CIBA Vision AOSEPT; Abbott Medical Optics UltraCare). Protein (bovine serum albumin and lysozyme) and various lipids were added to the lens cases during the neutralization phase to determine whether they influenced the rate of neutralization. Finally, rates were determined when the cases contained a silicone hydrogel lens material (lotrafilcon A) or Food and Drug Administration group IV (etafilcon A) lenses. Results: Neutralization for all three systems was complete within 90 minutes. The rate of neutralization for Clear Care and AOSEPT were not significantly different from each other (P=NS). UltraCare exhibited statistically higher levels of peroxide up to the 20-minute time point (P<0.001) Protein, lipid, or lens material did not significantly affect the rate of neutralization for any regimen (P=NS). Conclusions: Tablet-based one-step disinfection systems neutralize at a slower rate than disc-based peroxide systems, but this difference is only significant during the first 20 minutes after the onset of neutralization. Neither lens deposition nor lens material plays a role in the speed of neutralization of peroxide-based systems. © 2009 Lippincott Williams & Wilkins.

Abstracts

2016

Heynen M, Qiao H, Subbaraman L, Scales C, Riederer D, Fadli Z, Jones L. Location of non-polar lipids in monthly replacement silicone hydrogel contact lens materials. Optom Vis Sci 2016;93: E-abstract 166116. [ PDF ]

2015

Dantam J, Heynen M, Dominici C, Subbaraman L, Coles-Brennan C, Fadli Z, Jones L. Qualitative asymmetric mapping of lysozyme deposited on various contact lens materials using confocal laser scanning microscopy. Invest Ophthalmol Vis Sci 2015;56: E-abstract 6091. [ PDF ]

Jones L, Babaei Omali N, Heynen M, Coles-Brennan C, Fadli Z, Subbaraman L. Determining qualitative and quantitative uptake of lysozyme by various contact lens materials. BCLA Clinical Conference and Exhibition, 2015. [ PDF ]

Dantam J, Heynen M, Coles-Brennan C, Fadli Z, Subbaraman L.  Kinetics of lysozyme sorption by various contact lens materials over short time periods. BCLA Clinical Conference and Exhibition, 2015. [ PDF ]

Subbaraman L, Heynen M, McCanna D, Omali N, Jansen M, Fadli Z, Toubouti Y, Coles-Brennan C, Jones L . Impact of pigment presence in etafilcon A on in vitro interaction of lysozyme and impact on inflammatory biomarker release. Optom Vis Sci 2015;92: E-abstract 150097.

2014

Heynen M, Trieu D, Lorentz H, Jones L. Comparing and optimizing cholesterol extraction from hydrogel and silicone hydrogel contact lens materials. Invest Ophthalmol Vis Sci 2014;55: E-abstract 6058. [ PDF ]

Subbaraman L, Stahl U, Heynen M, Babaei Omali N, Canavan K, Jones L. Is there a difference in tear film and meibum composition in asymptomatic adapted contact lens and spectacle wearers?. BCLA Clinical Conference and Exhibition, 2014. [ PDF ]

Subbaraman L, Babaei Omali N, Heynen M, Lada M, Canavan K, Jones L. Could lipid deposition on contact lenses be beneficial?. BCLA Clinical Conference and Exhibition, 2014.

Babaei Omali N, Subbaraman L, Heynen M, Thangavelu M, Dare E, Canavan K, Fadli Z, Jones L. Protein Deposition on Senofilcon A Contact Lenses in Symptomatic and Asymptomatic Lens Wearers. Optom Vis Sci 2014;91: E-abstract 145186. [ PDF ]

Babaei Omali N, Subbaraman L, Schulze M, Heynen M, Canavan K, Fadli Z, Jones L. Clinical Signs, Symptoms, Tear Film and Meibum Composition in Asymptomatic Senofilcon A Contact Lens and Spectacle Wearers. Optom Vis Sci 2014;91: E-abstract 145185. [ PDF ]

Subbaraman L, Babaei Omali N, Heynen M, Lakkis C, Morgan P, Bertsen D, Nichols J, Jones L. Impact of different lens care solutions on protein deposition on various soft contact lenses: A multicenter study. Optom Vis Sci 2014;91: E-abstract 140057.

2013

Subbaraman L, Martell E, Heynen M, Ng A, Jones L. Kinetic activity of lysozyme when exposed to two differing contact lens care systems. Optom Vis Sci 2013;90: E-Abstract 130015.

2012

Lorentz H, Heynen M, Khan W, Trieu D, Jones L. The Impact of Intermittent Air Exposure on the Deposition of Lipids on Silicone Hydrogel and Conventional Hydrogel Contact Lens Materials . Invest Ophthalmol Vis Sci 2012;53:ARVO E-Abstract 3412.

Caffery B, Joyce E, Heynen M, Ritter R, Jones L, Senchyna M. TNF-Alpha MRNA expression in aqueous deficient dry eye. Optom Vis Sci 2012;89:E-abstract 120007.

Ng A, Heynen M, Subbaraman L, Jones L. Optimization of a novel fluorescent based lysozyme activity assay for contact lens studies. Optom Vis Sci 2012;89:E-abstract 120052.

2011

Jones L, Lorrentz H, Walther H, Heynen M, Kay L. Impact of lipid concentration, exposure time and tear film components on in vitro model lipid deposition to silicone hydrogel and hydrogel contact lens materials. International Society for Contact Lens Research (Napa Valley, California), 2011.

Muntz A, Lorentz H, Walther H, Heynen M, Joyce E, Sickenberger W, Jones L. Utility of a pulsating contact lens case to aid cholesterol removal from contact lens materials soaked in a no-rub MPS regimen. Contact Lens & Anterior Eye 2011;34,S1:S9.

Lorrentz H, Khan W, Trieu D, Heynen M, Jones L. The effect of intermittent air exposure on the deposition of lipids on silicone hydrogel and conventional hydrogel contact lens materials. NSERC 2020 Network Meeting (Orllia, Ontario), 2011.

Lorrentz H, Khan W, Trieu D, Heynen M, Jones L. The effect of intermittent air exposure on the deposition of lipids on silicone hydrogel and conventional hydrogel contact lens materials. International Society for Contact Lens Research (Napa Valley, California), 2011.

Fisher G, Leung T, Luensmann D, Heynen M, Jones L. 3D TOF-SIMS characterisation of drug-loaded silicone hydrogel contact lenses in the frozen hydrated state. 18th SIMS Conference (Trentino, Italy), 2011.

Walther H, Lorrentz H, Kay L, Heynen M, Jones L. The effect of in vitro lipid concentration on lipid deposition on silicone hydrogel and conventional hydrogel contact lens materials. Contact Lens & Anterior Eye 2011;34,S1:S21.

Jadi S, Heynen M, Luensmann D, Jones L. Incubation solution composition impacts in vitro protein uptake to silicone hydrogel contact lenses. Optom Vis Sci 2011;88:E-abstract 110546.

Ng A, Heynen M, Jones L. The impact of lactoferrin and lipids on kinetic lysozyme deposition on contact lenses. Optom Vis Sci 2011;88:E-abstract 110771.

Lorentz H, Walther H, Heynen M, Kay L, Jones L. Radiochemical kinetic uptake of three lipids on silicone hydrogel and conventional hydrogel contact lens materials. Invest Ophthalmol Vis Sci 2011;52:E-Abstract 6479.

2010

Srinivasan S, Martell E, Heynen M, Jones L. Clinical signs, tear lipocalin and lysozyme concentrations in postmenopausal women symptomatic of dry eye . 7th Canadian University Conference in Optometry (Montreal, Canada), 2010.

Heynen M, Lorentz H, Dumbleton K, Varikooty J, Woods C, Jones L. Lipid deposition on senofilcon A silicone hydrogel contact lenses disinfected with 1-step hydrogen peroxide and polyquad/aldox-preserved care regimens. 7th Canadian University Conference in Optometry (Montreal, Canada), 2010.

Srinivasan S, Martell E, Heynen M, Luensmann D, Cira D, Gorbet M, Jones L. Ocular surface sampling techniques. 7th Canadian University Conference in Optometry (Montreal, Canada), 2010.

Lorentz H, Heynen M, Jones L. Impact of tear film components on in vitro lipid uptake to silicone hydrogel and hydrogel contact lens materials. 7th Canadian University Conference in Optometry (Montreal, Canada), 2010.

Srinivasan S, Martell E, Heynen M, Luensmann D, Cira D, Gorbet M, Jones L. Ocular surface sampling techniques. 20:20 National Science and Engineering Council Network meeting (Horseshoe Valley, Ontario, Canada), 2010.

Lorrentz H, Heynen M, Jones L. Impact of tear film components on in vitro lipid uptake to silicone hydrogel and hydrogel contact lens materials. 20:20 National Science and Engineering Council Network Meeting (Horseshoe Valley, Ontario, Canada), 2010.

Jones L, Joyce E, Heynen M. Utility of a contact lens case pulsator to aid lysozyme removal from etafilcon A hydrogel lenses soaked in a no rub MPS regimen. Contact Lens & Anterior Eye 2010;33,6:290.

Jones L, Nguyen D, Weeks A, Heynen M, Joyce E, Sheardown H. Uptake and release of ciprofoloxacin by soft contact lens materials loaded with hyaluronic acid. Contact Lens & Anterior Eye 2010;33,6:286.

Lorentz H, Heynen M, Jones L. The impact of tear film components on in vitro lipid uptake to silicone hydrogel and hydrogel contact lens materials. Contact Lens & Anterior Eye 2010;33,6:268.

Jones L, Nguyen D, Weeks AK, Heynen M, Joyce E, Sheardown H. Uptake and release of ciprofloxacin by soft contact lens materials loaded with hyaluronic acid. Invest Ophthalmol Vis Sci 2010;51:ARVO E-Abstract 3412.

2009

Nguyen D, Weeks A, Heynen M, Joyce E, Sheardown H, Jones L. Uptake and release of ciprofloxacin by soft contact lens materials loaded with hyaluronic acid. 20:20 National Science and Engineering Council (NSERC) Network Meeting (Toronto, Canada), 2009.

Jones L, Heynen M, Joyce E, Lorentz H, Dumbleton K, Varikooty J, Woods C. Tear film deposition on silicone hydrogel contact lenses disinfected with hydrogen peroxide and rub or enhanced no-rub care regimens. Contact Lens & Anterior Eye 2009;32,5:249.

Luensmann D, Heynen M, Jones L. Penetration profile of lysozyme and albumin in silicone hydrogel and pHEMA-based contact lens materials assessed using confocal microscopy. Contact Lens & Anterior Eye 2009;32,5:224.

Luensmann D, Heynen M, Jones L. Determination of albumin sorption to intraocular lenses by radiolabeling and confocal scanning laser microscopy. Ivey Research Institute Day (London, Canada), 2009.

Heynen M, Lorentz H, Dumbleton K, Varikooty J, Woods C, Jones L. Lipid deposition on senofilcon A silicone hydrogel contact lenses disinfected with 1-step hydrogen peroxide and polyquad/aldox-preserved care regimens. Invest Ophthalmol Vis Sci 2009;49:E-abstract 5660.

Jones L, Heynen M, Joyce E, Lorentz H, Dumbleton K, Varikooty J, Woods C. Tear film deposition on silicone hydrogel contact lenses disinfected with hydrogen peroxide and rub or enhanced no-rub care regimens. Optom Vis Sci 2009;86:E-abstract 095929.

Jones L, Joyce E, Heynen M. Utility of a contact lens case pulsator to aid lysozyme removal from etafilcon A hydrogel lenses soaked in a no rub MPS regimen. Optom Vis Sci 2009;86:E-abstract 090650.

Luensmann D, Heynen M, Liu L, Sheardown H, Jones L. The impact of rub & no-rub care products on protein removal and localization. Optom Vis Sci 2009;86:E-abstract 090517.

Spurr-Michaud SJ, Senchyna M, Srinivasan S, Ritter III R, Heikkila E, Heynen M, Jones L, Gipson I. Assay of membrane-associated mucins in conjunctiva and tears of postmenopausal women with and without dry eye. Invest Ophthalmol Vis Sci 2009;50: E-Abstract 539.

Ngo W, Heynen M, Joyce E, Jones L. Impact of protein, lipid and lens polymer on neutralization times of hydrogen peroxide care regimens. Optom Vis Sci 2009;86:E-abstract 095631.

2008

Luensmann D, Heynen M, Jones L. Albumin penetration into intraocular lenses imaged by confocal microscopy. Optom Vis Sci 2008;85; E-abstract 80029.

Jones L, Boone A, Heynen M, Joyce E, Varikooty J. Ex vivo protein deposition on two-weekly daily wear silicone hydrogel contact lens materials. Contact Lens & Anterior Eye 2008;31,5:262-263.

2007

Boone A, Heynen M, Joyce E, Varikooty J, Jones L. Ex vivo protein deposition on two-weekly daily wear silicone hydrogel contact lens materials. Optom Vis Sci 2007;84: E-abstract 075140.

Luensmann D, Heynen M, Jones L. The use of confocal microscopy to investigate albumin penetration into pHEMA-based and silicone hydrogel contact lens materials. Invest Ophthalmol Vis Sci 2007;48: E-abstract 5377.

Spurr-Michaud S, Senchyna M, Srinivasan S, Ritter R, Argueso P, Joyce E, Heynen M, Jones L, Gamache D, Gipson I. Assay of MUC16 in conjunctiva and tears of postmenopausal women with and without dry eye. 5th International Conference on the Tear Film and Ocular Surface (Sicily, Italy), 2007.

Srinivasan S, Joyce E, Heynen M, Jones L, Simpson T, Gamache D, Senchyna M. Expression of soluble and membrane bound MUC16 in dry eyed postmenopausal women. 5th International Conference on the Tear Film and Ocular Surface (Sicily, Italy), 2007.

Caffery B, Joyce E, Heynen M, Ritter R, Jones L, Simpson T, Slomovic A, Gamache D, Senchyna M. Tear flow and MUC16 expression in Sjögren’s Syndrome, KCS and normals. 5th International Conference on the Tear Film and Ocular Surface (Sicily, Italy), 2007.

Luensmann D, Heynen M, Jones L. The use of confocal microscopy to investigate albumin penetration into pHEMA-based and silicone hydrogel contact lens materials. Biomedical Imaging and Computer Vision (BICV) Workshop (University of Waterloo, Canada), 2007.

Luensmann D, Heynen M, Jones L. The use of confocal microscopy to investigate albumin penetration into pHEMA-based and silicone hydrogel contact lenses. 6th Canadian Optometry Conference on Vision Science, Waterloo, Ontario, 2007.

Luensmann D, Heynen M, Jones L. Confocal microscopy and albumin penetration into contact lenses. Optom Vis Sci 2007;84,9:839-847.

Walther H, Lorentz H, Heynen M, Kay L, Jones L. The effect of concentration the in vitro radiochemical uptake of three lipids on silicone hydrogel and conventional hydrogel contact lens materials. Contact Lens & Anterior Eye ;34,s21:.

Professional Publications

2012

Nguyen D, Hui A, Weeks A, Heynen M, Martell E, Sheardown H, Jones L. Release of Ciprofloxacin-HCl and Dexamethasone phosphate by soft contact lens materials loaded with Hyaluronic Acid. Materials 2012;5684-698.