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Peer-reviewed articles

2021

Das,N., Menon,N., DeAlmeida,L., Woods,P., Heynen,M., Jay,G., Caffery,B., Krawetz,R., Schmidt,T. Dufour,A. Proteomics analysis of tears and saliva from Sjogren’s syndrome patients Frontiers in Pharmacology 2021;12(3299):787193 [ Show Abstract ]

Sjogren's syndrome (SS) is characterized by dysfunctional mucous membranes and dysregulated moisture-secreting glands resulting in various symptoms, including dry mouth and dry eyes. Here, we wanted to profile and compare the tear and saliva proteomes of SS patients to healthy controls. Tear and saliva samples were collected and subjected to an isotopic dimethylation labeling shotgun proteomics workflow to identify alterations in protein levels. In tear samples, we identified 83 upregulated and 112 downregulated proteins. Pathway enrichment analysis of the changing proteins by Metascape identified leukocyte transendothelial migration, neutrophil degranulation, and post-translation protein phosphorylation in tears of SS patients. In healthy controls' tears, an enrichment for proteins related to glycolysis, amino acid metabolism and apoptotic signaling pathway were identified. In saliva, we identified 108 upregulated and 45 downregulated proteins. Altered pathways in SS patients' saliva included cornification, sensory perception to taste and neutrophil degranulation. In healthy controls' saliva, an enrichment for proteins related to JAK-STAT signaling after interleukin-12 stimulation, phagocytosis and glycolysis in senescence were identified. Dysregulated protease activity is implicated in the initiation of inflammation and immune cell recruitment in SS. We identified 20 proteases and protease inhibitors in tears and 18 in saliva which are differentially expressed between SS patients and healthy controls. Next, we quantified endogenous proteoglycan 4 (PRG4), a mucin-like glycoprotein, in tear wash and saliva samples via a bead-based immune assay. We identified decreased levels of PRG4 in SS patients' tear wash compared to normal samples. Conversely, in saliva, we found elevated levels of PRG4 concentration and visualized PRG4 expression in human parotid gland via immunohistological staining. These findings will improve our mechanistic understanding of the disease and changes in SS patients' protein expression will help identify new potential drug targets. PRG4 is among the promising targets, which we identified here, in saliva, for the first time.

Heynen,M., Ng,A., Martell,E., Subbaraman,L. N., Jones,L. Activity of Deposited Lysozyme on Contemporary Soft Contact Lenses Exposed to Differing Lens Care Systems Clinical Ophthalmology 2021;15(April):1727-1733 [ Show Abstract ]

Purpose: The amount of protein deposition on soft contact lenses and to what extent the proteins are denatured may have an impact on comfortable wearing times of contact lenses. The purpose of this study was to evaluate the effects of two lens care systems on total protein and the quantity and activity of lysozyme deposited on worn senofilcon A, silicone hydrogel contact lenses.

Participants and Methods: Thirty symptomatic soft contact lens wearers were enrolled into a 4-week prospective, randomized, bilateral eye, daily-wear, crossover, double-masked study. Participants were fitted with biweekly senofilcon A lenses and were assigned either a polyquaternium-1 and myristamidopropyl dimethylamine-containing system (OPTI-FREE RepleniSH) or a peroxide-based system (CLEAR CARE). After each wear period, proteins were extracted from the lenses and analyzed for total protein, total lysozyme quantity and activity.

Results: The use of either the peroxide-based system or the polyquaternium-1 and myristamidopropyl dimethylamine-containing system resulted in no difference (P> 0.05) to the amount of total protein deposited on the lenses (6.7 ± 2.8 micrograms/lens versus 7.3 ± 2.8 micrograms/lens, respectively) or to the amount of denatured lysozyme deposits (0.8 ± 0.7 versus 0.9 ± 0.7 micrograms/lens), respectively. The total amount of lysozyme deposited on the lenses was significantly lower when using the peroxide-based system (1.3 ± 0.9 micrograms/lens) compared to the polyquaternium-1 and myristamidopropyl dimethylamine-containing system (1.7 ± 1.0 micrograms/lens) (P=0.02).

Conclusion: The inactivation of lysozyme deposited on senofilcon A lenses when disinfected with the peroxide-based or the polyquaternium-1 and myristamidopropyl dimethylamine-containing systems were neither statistically nor clinically significant and the overall amounts of denatured lysozyme recovered from the lenses were low (< 1 microgram/lens).

Omali,N. B., Subbaraman,L. N., Heynen,M., Lada,M., Canavan,K., Fadli,Z., Ngo,W., Jones,L. Lipid deposition on contact lenses in symptomatic and asymptomatic contact lens wearers Cont Lens Anterior Eye 2021;44(1):56-61 [ Show Abstract ]

Purpose
Lipid deposition on contact lenses (CL) has traditionally been believed to reduce comfort during CL wear. The purpose of this study was to quantify lipid deposition on CL in a group of symptomatic and asymptomatic adapted CL wearers.

Methods
This was a single-masked, randomized clinical trial. Only confirmed symptomatic (comfortable lens wear time (CWT) 10 h and minimal reduction in comfort over the course of the day) participants were recruited to participate in the study. Participants wore senofilcon A lenses in combination with a polyquaternium-based care solution (OPTI-FREE Replenish). Worn CL samples were collected on Day 14. Deposited lipid amounts from the lenses (including cholesteryl ester, cholesterol and triolein) were quantified using a liquid chromatography-mass spectrometry technique.

Results
Lipid deposition was significantly higher in CL extracts of asymptomatic wearers compared to the symptomatic wearers for all lipid types quantified, including cholesteryl ester (2.1 ± 0.6 vs 1.6 ± 0.5 log μg/lens), cholesterol (1.5 ± 0.3 vs 1.1 ± 0.3 log μg/lens) and triolein (0.3 ± 0.2 vs 0.1 ± 0.1 log μg/lens) (all p < 0.002). The amount of cholesteryl ester deposited was greatest (p = 0.0001), followed by cholesterol, then triolein, for both the asymptomatic and symptomatic groups (both p = 0.0001).

Conclusion
This study demonstrated that the asymptomatic group deposited a significantly greater amount of lipid on their CL. Although lipid levels measured are considered low to trigger any observable clinical deposition, they may influence other clinical outcomes, particularly comfort.

Phan,C. M., Shukla,M., Walther,H., Heynen,M., Suh,D., Jones,L. Development of an In Vitro Blink Model for Ophthalmic Drug Delivery Pharmaceutics 2021;13(Article 300):1-10 [ Show Abstract ]

Purpose: The purpose of this study was to develop an advanced in vitro blink model that
can be used to examine the release of a wide variety of components (for example, topical ophthalmic
drugs, comfort-inducing agents) from soft contact lenses. Methods: The model was designed using
computer-aided design software and printed using a stereolithography 3D printer. The eyelid and
eyeball were synthesized from polyvinyl alcohol and silicone material, respectively. Simulated
tear fluid was infused through tubing attached to the eyelid using a syringe pump. With each
blink cycle, the eyelid slides and flexes across the eyeball to create an artificial tear film layer. The
flow-through fluid was collected using a specialized trough. Two contact lenses, etafilcon A and
senofilcon A, were incubated in 2 mL of a water-soluble red dye for 24 h and then placed on the eye
model (n = 3). The release of the dye was measured over 24 h using a tear flow rate of 5 µL/min.
Results: Approximately 25% of the fluid that flowed over the eye model was lost due to evaporation,
nonspecific absorption, and residual dead volume. Senofilcon A absorbed more dye (47.6 ± 2.7 µL)
than etafilcon A (22.3 ± 2.0 µL). For etafilcon A, the release of the dye followed a burst-plateau
profile in the vial but was sustained in the eye model. For senofilcon A, the release of the dye was
sustained in both the vial and the eye model, though more dye was released in the vial (p < 0.05).
Overall, the release of the dye from the contact lenses was higher in the vial compared with the eye
model (p < 0.05). Conclusion: The blink model developed in this study could be used to measure
the release of topical ophthalmic drugs or comfort agents from contact lenses. Simulation of a blink
mechanism, an artificial tear film, and nonspecific absorption in an eye model may provide better
results than a simple, static vial incubation model.

Walther,H., Lorentz,H., Heynen,M., Kay,L., Jones,L. W. The Impact of Incubation Conditions on in Vitro Phosphatidylcholine Deposition on Contact Lens Materials Optometry & Vision Science 2021;98(4):341-349 [ Show 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.

Yang,M., Ngo,W., Srinivasan,S., Heynen,M. L., Dantam,J., Subbaraman,L. N., Jones,L., Senchyna,M. Optimization of goblet cell density quantification methods Experimental Eye Research 2021;207(June):108607 [ Show Abstract ]

The purpose of this study was to develop a standardized, accurate and efficient method for estimating conjunctival goblet cell density (GCD) via optimizing sample storage conditions and quantification methods. Conjunctival impression cytology (CIC) membranes were collected from both eyes of 32 participants and were randomized to two storage durations (2-3 weeks, 6-7 weeks) and two storage container types (microcentrifuge tube, flat histology cassette). The CIC membranes were stained and subdivided into 25 areas (5 mm × 5 mm) for imaging and the GCs were counted under 200X magnification using three different methods: (1) full CIC membrane GC count of the 25 images with cell-counting software ("full"; reference method), (2) partial membrane GC count of 9 images with cell-counting software ("partial"), and (3) manual counting of the 25 images ("manual"). In all cases, GCD was determined by dividing the GC count by the counting area. The average time required for quantification was recorded to gauge efficiency. Results showed no significant difference in GC count between the two storage durations (p = 0.745) or storage container types (p = 0.552). The median (interquartile range (IQR)) time required to quantify a CIC membrane for the full, partial, and manual methods of GC counting, was 14.8(17.6), 4.6(5.2) and 5.0 (5.0) minutes, respectively. The agreement of GCD values between the full and manual methods (bias: 0.4, 95% LOA: [-4.6, 5.5]) was stronger than that comparing the full and partial methods (bias: 0.5, 95% LOA: [-18, 17]). All together, through systematic examination of key procedural variables, an optimized method for GCD quantification within 7 weeks of sample collection was outlined. Adaption of procedures described in this paper to facilitate accurate and efficient GCD quantification may serve as a valuable step in clinical trials investigating DED pathophysiology and/or novel DED treatment strategies.

Yee,A., Chan,V., Heynen,M., Phan,C. M., Jones,L. Uptake and release of a multipurpose solution biocide (MAP-D) from hydrogel and silicone hydrogel contact lenses using a radiolabel methodology Eye & Contact Lens 2021;47(5):249-255 [ Show Abstract ]

Purpose:
The purpose of this study was to evaluate the uptake and release of radiolabelled myristamidopropyl dimethylamine (MAP-D) on reusable daily wear contact lenses (CLs) over 7 days.

Methods:
Three silicone hydrogel (SH) CL materials (lotrafilcon B, balafilcon A, senofilcon A) and two conventional hydrogel (CH) materials (etafilcon A, omafilcon A) were tested. A short-term (experiment 1, N=4) and a longer-term (experiment 2, N=3) study was conducted. In experiment 1, the CLs were incubated in 2 mL of phosphate buffered solution (PBS) containing 14C MAP-D (5 μg/mL) for 8 hrs. The release of 14C MAP-D was measured at t=0.25, 0.5, 1, 2, 4, 8, and 24 hr in PBS. In experiment 2, the CLs were incubated in the 14C MAP-D solution for 8 hrs followed by a 16-hr release in PBS. This cycle was repeated daily for 7 days. At the end of both experiments, lenses were extracted to determine the total uptake of MAP-D. The radioactivity was measured using a beta scintillation counter.

Results:
In experiment 1, all three SH lenses sorbed similar amounts of MAP-D (P=0.99), all of which were higher than the two CH materials (P<0.01). However, the CH materials released a greater amount of MAP-D than the SH materials (P<0.01). In experiment 2, the uptake of MAP-D in SH materials increased over 7 days, whereas the amount of MAP-D remained constant in the CH materials (P=0.99). Similar to experiment 1, the CH lenses released more MAP-D than SH lenses after 7 days (P<0.01).

Conclusion:
The SH materials absorbed greater amounts of MAP-D compared to CH materials. However, the CH materials released the greatest amount of MAP-D. Radioactive labelling of MAP-D offers a highly sensitive method of assessing the uptake and release profiles of biocides to CL materials.

2020

Luensmann,D., Omali,N. B., Suko,A., Drolle,E., Heynen,M., Subbaraman,L. S., Scales,C., Fadli,Z., Jones,L. Kinetic Deposition of Polar and Non-polar Lipids on Silicone Hydrogel Contact Lenses Current Eye Research 2020;45(12):1477-1483 [ Show Abstract ]

Purpose: This study investigated kinetic lipid uptake to four silicone hydrogel (SiHy) lenses over a period of four weeks, using an in-vitro radiolabel method.

Methods: Four contemporary monthly replacement SiHy lenses (lotrafilcon B, senofilcon C, comfilcon A, samfilcon A) were incubated in three different solutions: 1) An artificial tear solution (ATS) containing 14C-labeled phosphatidylcholine (PC), 2) an ATS containing 14C-cholesteryl oleate (CO) and 3) an ATS containing four 14C-radiolabeled lipids (PC, phosphatidylethanolamine, CO, and cholesterol (total lipid)). After 16 hours, lipids were extracted twice from the lenses with chloroform:methanol and the radioactive counts determined the lipid quantities to simulate 1 day of wear. OPTI-FREE PureMoist (Alcon) was used to clean and disinfect the remaining lenses daily and the lipid quantities were further determined after 2 weeks and 4 weeks.

Results: The amount of total lipid increased for all lenses over time (p < .01). After four weeks, total lipid accumulated was 20.26 ± 0.15 µg/lens for senofilcon C, which was significantly higher (p < .01) than all other lens materials (samfilcon A - 17.84 ± 0.21; comfilcon A - 16.65 ± 0.12; lotrafilcon B - 7.41 ± 0.56 µg/lens). CO was highest on lotrafilcon B (1.26 ± 0.13 µg/lens) and senofilcon C attracted the most PC (3.95 ± 0.12 µg/lens) compared to the other materials.

Conclusion: The amount of both polar and non-polar lipid deposition on monthly replacement SiHy lenses increased over 4 weeks, with significant differences being seen between lens materials.

Qiao,H., Luensmann,D., Heynen,M., Drolle,E., Subbaraman,L. N., Scales,C., Riederer,D., Fadli,Z., Jones,L. In Vitro Evaluation of the Location of Cholesteryl Ester Deposits on Monthly Replacement Silicone Hydrogel Contact Lens Materials Clinical Ophthalmology 2020;14(September):2821-2828 [ Show Abstract ]

Purpose: The deposition profile of cholesteryl ester on the surface and throughout the matrix of silicone hydrogel contact lens (CL) materials was determined under conditions that mimic a daily wear regimen.

Methods: In this in vitro study, four SiHy CL materials (senofilcon C, lotrafilcon B, comfilcon A and samfilcon A) were incubated in an artificial tear solution (ATS) for up to 30 days. CL incubation was alternated between the ATS (16 hours) and a multipurpose care regimen (8 hours). The ATS included fluorescently tagged cholesteryl ester (5-cholesten-3ß-ol 6-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]caproate; CE-NBD) and confocal laser scanning microscopy visualized the distribution of the lipid through the CLs.

Results: The distribution of CE-NBD was homogenous from the anterior to posterior surface in senofilcon C and comfilcon A, at all time points. For lotrafilcon B and samfilcon A, CE-NBD localization was heterogeneous, with greater amounts on the surfaces on Day 1 and Day 14 compared to the lens matrix; however, differences in concentration between the surface and bulk diminished by Day 30.

Conclusion: The distribution of the non-polar lipid CE-NBD varied with lens material chemistry. While some lens materials deposited the lipid primarily on the surface after 16 hours of exposure, all materials exhibited a homogenous distribution after one month.

Keywords: lipid distribution, silicone hydrogel contact lenses, cholesteryl ester, artificial tear solution

2018

Omali,N.B., Subbaraman,L.N., Heynen,M., Ng,A., Coles-Brennan,C., Fadli,Z., Jones,L. Surface versus bulk activity of lysozyme deposited on hydrogel contact lens materials in vitro Contact Lens and Anterior Eye 2018;41(4):329-334 [ Show Abstract ]

Purpose: To determine and compare the levels of surface versus bulk active lysozyme deposited on several commercially available hydrogel contact lens materials. Methods: Hydrogel contact lens materials [polymacon, omafilcon A, nelfilcon A, nesofilcon A, ocufilcon and etafilcon A with polyvinylpyrrolidone (PVP)] were incubated in an artificial tear solution for 16 h. Total activity was determined using a standard turbidity assay. The surface activity of the deposited lysozyme was determined using a modified turbidity assay. The amount of active lysozyme present within the bulk of the lens material was calculated by determining the difference between the total and surface active lysozyme. Results: The etafilcon A materials showed the highest amount of total lysozyme activity (519 ± 8 μg/lens, average of Moist and Define), followed by the ocufilcon material (200 ± 5 μg/lens) and these two were significantly different from each other (p < 0.05). The amount of surface active lysozyme on etafilcon and ocufilcon lens materials was significantly higher than that found on all other lenses (p < 0.05). There was no active lysozyme quantified in the bulk of the nelfilcon material, as all of the active lysozyme was found on the surface (1.7 ± 0.3 μg/lens). In contrast, no active lysozyme was quantified on the surface of polymacon, with all of the active lysozyme found in the bulk of the lens material (0.6 ± 0.6 μg/lens). Conclusions: The surface and bulk activity of lysozyme deposited on contact lenses is material dependent. Lysozyme deposited on ionic, high water content lens materials such as etafilcon A show significantly higher surface and bulk activity than many other hydrogel lens materials.

2017

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.

Omali,N. B., Subbaraman,L. N., Heynen,M., Fadli,Z., Coles-Brennan,C., Jones,L. W. In Vitro Effect of Lysozyme on Albumin Deposition to Hydrogel Contact Lens Materials Optometry and Vision Science 2017;94(11):1047-1051 [ Show Abstract ]

SIGNIFICANCE: Albumin deposition on contact lenses could be detrimental to contact lens (CL) wear because this may increase the risk of bacterial binding and reduce comfort. Lysozyme deposition on selected lens materials would reduce albumin deposition on lenses. PURPOSE: This study aims to determine if lysozyme deposition on CLs could act as a barrier against subsequent albumin adsorption, using an in vitro model. METHODS: Six hydrogel CL materials (etafilcon A, polymacon, nelfilcon A, omafilcon A, ocufilcon B, and nesofilcon A) were evaluated. Four CLs of each type were soaked in lysozyme solution for 16 hours at 37°C. Lysozyme-coated lenses were then placed in vials with 1.5 mL of artificial tear solution containing 125I-labeled albumin for 16 hours at 37°C with shaking. Four uncoated lenses of each type were used as controls. Lenses soaked in radiolabeled albumin were rinsed in a phosphate-buffered saline solution, and radioactive counts were measured directly on lenses using a gamma counter. Albumin uptake on lenses was measured using a calibration curve by plotting radioactive counts versus protein concentration. RESULTS: Results are reported as mean ± SD. Lysozyme-coated etafilcon A lenses exhibited lower levels of deposited albumin than uncoated etafilcon A lenses (58 ± 12 vs. 84 ± 5 ng/lens; P .05). Uncoated nesofilcon A lenses deposited the highest amount of albumin when compared with other uncoated lenses (P <.05). CONCLUSIONS: This study demonstrates that lysozyme deposited onto etafilcon A resists the deposition of albumin, which may potentially be beneficial to CL wearers. Copyright © 2017 American Academy of Optometry.

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;161:1-9 [ 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

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. 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.

Scientific Presentations

2023

Hui A, Heynen M, Chan V, Mirzapour P, Enstone D, Saad M, George M, Ngo W, Jones L. The impact of RGP care solutions on ISO measured lens parameters and the protein deposition on RGP lenses when managed with a hydrogen peroxide care solution Global Specialty Lens Symposium, Las Vegas, Jan 20, 2023 [ PDF ]

2020

Phan CM, Shukla M, Heynen M, Walther H, Jones L. Development of an In Vitro Blink Model for Measuring Drug and Comfort Agent Elutes from Soft Contact Lens Polymers Academy at Home, 2020 [ Show Abstract ]

Purpose: To develop an advanced in vitro blink model that could be used to examine release of a wide variety of components (topical drugs; comfort agents etc) from soft contact lenses.
Methods: The model was designed using CAD software and 3D printed using an SLA printer. A UV-curable resin polymer was used to fabricate the main components of the eye model to ensure water-sealed parts. The eyelid and eyeball were synthesized from a polyvinyl alcohol and a silicone material respectively. Simulated tear fluid is delivered through tubing attached to the eyelid. With each blink cycle (1 blink/10s), the eyelid slides and flexes across the eyeball to create an artificial tear film. The flow-through fluid is collected in a specialized trough. Two contact lenses, etafilcon A and senofilcon A, were incubated in 2 mL of a water-soluble red dye for 24 hours and then placed on the eye model. The release of the dye was measured at t= 0.5, 1, 2, 4, 8, 12, and 24 hours (n=3) in phosphate buffered saline (flow rate = 5 µL/min). The dye release from the lenses was also evaluated in a vial containing 2 mL of PBS over 24 hours (n=3). The amount of dye in the samples was determined using a UV/Vis spectrophotometer at 520 nm.
Results: All of the contact lenses were visibly red after the incubation with the dye. After the release studies, the etafilcon A lenses became transparent with a slight red tint, whereas the senofilcon A lenses retained a moderate red colour. For the vial study, the release of the dye from the contact lenses was rapid within the first 4 hours, which was then followed by a slower release phase. In contrast, dye release from the lenses on the eye model was significantly slower and was sustained over the 24-hour period. The total amounts of dye released in the eye model were also significantly lower compared to the vial (p<0.05), which could be attributed to the absorption of the dye into the eyelid. From the total amount of tear fluid (7.2 mL) that was infused into the eye model, approximately 5.2 ± 0.6 mL of flow-through was collected. The loss of fluid can be attributed to fluid absorption into the eyelid and contact lenses, as well as evaporation.
Conclusion: The blink model developed in this study could be used to measure the release of topical ophthalmic drugs or comfort agents from contact lenses. The results showed that the release kinetics of a dye from contact lenses on the eye model was significantly different than that of a vial. The model also simulated non-specific absorption of the dye into the eyelid. Future work will focus on developing polymers to simulate the absorption of drugs on the eye.

Yee A, Phan CM, Heynen M, Walther H, Jones L. The uptake and release kinetics of myristamidopropyl dimethylamine (MAP-D) from contact lenses using radioactive labelling he Association for Research in Vision and Ophthalmology, 2020 [ Show Abstract ][ PDF ]

Purpose : Biocides are an important disinfecting component commonly found in contact lens (CL) multipurpose solutions (MPS). During the disinfection step, the uptake of biocides into CL materials can significantly reduce the efficacy of the MPS to disinfect the lens. An increased release of biocides from the CL can lead to clinical complications such as discomfort and corneal staining. However, detection methods using chromatography and spectrometry can be time-consuming and have low sensitivity. The purpose of this study was to evaluate the uptake and release of myristamidopropyl dimethylamine (MAP-D; ALDOX®) using a radiolabel method.

Methods : Radioactive (14C) MAP-D was purchased from Moravek Inc. (CA, USA). Five soft CL materials (lotrafilcon B, balafilcon A, senofilcon A, etafilcon A, omafilcon A) were tested (N=4). The lenses were incubated in PBS (ISO 18369-3) solution containing 2mL of 14C radioactive MAP-D (5µg/mL) for 8 hours, followed by a release period in PBS for 16 hours. The cycle was continued over a 7-day period with a new replenishing solution for each day. The samples were counted for their radioactive signal (CPM) using the LS6500 Beckman Coulter liquid scintillation beta counter (ON, CA). A standard curve was used to convert CPM to µg of MAP-D.

Results : After 7-days, the silicone hydrogel (SH) lenses, lotrafilcon B (36.21±0.42µg), balafilcon A (36.29±1.15µg) and senofilcon A (35.54±1.37µg) had a significantly greater uptake of MAP-D compared to the conventional hydrogel (CH) lenses, etafilcon A (7.66±1.19µg) and omafilcon A (6.54±0.94µg) (p<0.01). However, the percent of MAP-D released was higher for CH lenses, etafilcon A (80%), omafilcon A (93%) compared to SH lenses, lotrafilcon B (25%), balafilcon A (19%) and senofilcon A (19%) over the 7-days (p<0.01).

Conclusions : Radioactive labelling offers a highly sensitive and accurate way of assessing the uptake and release kinetics of MAP-D to CL materials. Greater uptake of MAP-D occurs to SH materials, and the release of MAP-D is relatively minor. While CH materials take up only low amounts of MAP-D, the majority of it is easily released from these materials.

This is a 2020 ARVO Annual Meeting abstract.

2019

Jones L, Jabeen A, Subbaraman L, Heynen M, Keir N, Srinivasan S. Method optimization to quantify four different neuropeptides in the human tear film Global Specialty Lens Symposium, Las Vegas, Nevada, 2019 [ PDF ]

Yee A, Chan V, Heynen M, Jones L. A radioactive labelling technique for evaluating the uptake and release of myristamidopropyl dimethylamine (MAP-D) from contact lenses Invest Ophthalmol Vis Sci 2019;E-abstract 6370 [ Show Abstract ][ PDF ]

Purpose: The uptake and subsequent release of biocides from contact lens (CL) materials is of relevance as it has been linked with outbreaks of microbial keratitis and potential cytotoxic responses. Previous uptake and release studies of myristamidopropyl dimethylamine (MAP-D; ALDOX®) have used light-scattering techniques, which are time consuming and have relatively low sensitivity. The purpose of this study was to develop a radioactive labelling technique in order to improve the accuracy and sensitivity of biocide uptake and release to CL materials.

Methods: Four soft CL materials (lotrafilcon A, balafilcon A, senofilcon A, etafilcon A) were tested (N=4). Radioactive (14C) MAP-D was purchased from Moravek Inc. (California, USA). The lenses were incubated in PBS (ISO 18369-3) solution containing radioactive MAP-D (5µg/mL) for 8 hours. After the incubation period of 8 hours, the lenses were placed into the release condition. The release of MAP-D was assessed over 24 hours in 2 mL of PBS. Aliquots were removed at 0.25, 0.5, 1, 2, 4, 8, and 24 hour time points and added to scintillation fluor (PerkinElmer, USA). The samples were counted for their radioactive signal (CPM) using the LS6500 Beckman Coulter liquid scintillation beta counter (Beckman Coulter, ON, CA). The CPM was converted to µg of MAP-D based on a standard curve.

Results: After the incubation period of 8 hours, the uptake of MAP-D by etafilcon A (2.78±0.19µg) was significantly different than lotrafilcon A (4.69±0.1µg, p<0.01), balafilcon A (4.55±0.31µg, p<0.01), and senofilcon A (4.35±0.13µg, p<0.01). The total amount of MAP-D released by etafilcon A (1.41±0.09µg) was significantly greater than lotrafilcon A (0.27±0.02µg, p<0.01), balafilcon A (0.23±0.04µg, p<0.01), and senofilcon A (0.21±0.01µg, p<0.01). The results demonstrate that the uptake of MAP-D was higher for all silicone hydrogel (SH) lenses and lower for the conventional hydrogel lens. The release profile of etafilcon A was greater than the SH lenses, with a burst release of 0.33µg at 0.25 hr.

Conclusions: Radioactive labelling of MAP-D offers a highly sensitive, accurate way of assessing the uptake and release profiles of biocides to CL materials. Future studies using this methodology will investigate the profiles for other biocides, such as polyhexamethylene biguanide (PHMB), a common biocide used in CL solutions.

2018

Jabeen A, Subbaraman L, Heynen M, Srinivasan S, Jones L. Method Optimization to Quantify Four Neuropeptides in the Human Tear Film American Academy of Optometry, San Antonio, USA, 2018 [ Show Abstract ][ PDF ]

Purpose: Ocular surface neuropeptides play a key role in modulating the infiltration and activation of immune cells in both tearing and ocular discomfort. The purpose of this study was to optimize a method to quantify the amount of four neuropeptides - calcitonin gene-related peptide (CGRP), Substance P (SP), Neuropeptide Y (NPY) and Vasoactive Intestinal Peptide (VIP) - in the human tear film

Methods: Basal and flush tears (following instillation of 20 microliters of saline on the ocular surface) of 8 healthy participants were collected from the right and left eyes respectively, using a microcapillary method on day 1. On day 2, the same procedure was repeated. The concentration of the four neuropeptides in the tears was determined using an enzyme-linked immunosorbent assay (ELISA) method. The ELISA kits were tested for specificity and sensitivity as per manufacturer’s guidelines and the experiments were repeated three times to determine reproducibility. The limit of detection was based on the variance of the blank samples and the variance of the lowest level of each individual tear samples added.

Results: RM-ANOVA showed no statistical difference in the concentration of CGRP, NPY and VIP between basal and flush tears for days 1 and 2 (p > 0.05). However, statistically significant differences were found for SP between basal and flush tears for day 1 (p = 0.037) and flush tears for days 1 and 2 (p = 0.018) respectively.

Conclusion: ELISA is a sensitive method that can be adopted to quantify neuropeptides in the human tear film. The optimized technique can be used to identify differences in the level of various neuropeptides in patients with contact lens discomfort and varying degrees of dry eye.

Schmidt T, Srinivasan S, Heynen M, Jay G, Sullivan B, Subbaraman L, Caffery B, Jones L, Regmi S. Quantification of proteoglycan 4 (PRG4) / lubricin in normal and Sjögren Syndrome human tears Invest Ophthalmol Vis Sci 2018;E-Abstract 3827 [ Show Abstract ]

Purpose: Sjögren’s syndrome (SS) is an autoimmune disease with hallmark clinical symptoms of dry eye and dry mouth. Proteoglycan 4 (PRG4), or lubricin, is a boundary lubricant that is naturally present on the ocular surface and in tears. Recently PRG4 in human tears was shown to be susceptible to proteolytic digestion by cathepsin S, an enzyme with increased activity in SS tears, which destroyed the in vitro ocular surface boundary lubricating ability. However, whether levels of PRG4 are diminished in SS tears remains to be determined. The objective of this study was to quantify PRG4 levels in normal and SS human tears.

Methods; Tears were collected from 17 SS (15 F, 2 M, 56.2±16.7 years old) and 20 asymptomatic (n=20, 7 M, 13 F, 31.2±11.4 years old) participants, with approval from the Office of Research Ethics (UWaterloo). SS participants were diagnosed using the American European Consensus Criterion. Tears were collected without anaesthetic, from the inferior temporal tear meniscus of each eye, using a disposable microcapillary tube and frozen at -80C until use. The concentration of PRG4 was determined via a sensitive, competitive amplified luminescent proximity homogeneous assay using recombinant human PRG4 as the control. Total mass of PRG4 was calculated by normalizing concentration by tear volume, using 5.0 ul for normal tears and measured SS tear volume (0.1 to 2.3 ul). Data is reported as mean±SD, nonparametric statistics were employed (Mann-Whitney U & Levine tests).

Results; The concentration of PRG4 in SS (28.6±44.3 ug/ml) was not significantly different than that of normal tears (2.6±2.0 ug/ml, p=0.15), but did demonstrate significantly greater variation (p<0.001). The mass of PRG4 in SS tears (10.6±4.8 ng) was significantly diminished compared to normal tears (12.8±1.4 ng, p<0.05).

Conclusions; PRG4 concentration is significantly more variable in SS tears, and when normalized by volume, the PRG4 mass in SS tears is diminished compared to normal tears. These data suggest either a reduction in PRG4 production or an increase in PRG4 catabolism in SS tears relative to normal tears, which could be the cause of the variability of PRG4 concentration in SS tears. Given the role PRG4 plays in ocular surface health and its susceptibility to degradation by cathepsin S in SS tears, diminished PRG4 could contribute to signs and symptoms of dry eye in SS.

2017

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 Canadian Optometry Schools Research Conference, 2017

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, 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 ]

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 ]

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

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 ]

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, 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

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

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 ]

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

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

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

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

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

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

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

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

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

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

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

Walther H, Lorentz H, Heynen M, Kay L, Jones L. The effect of in vitro lipid concentration on lipid deposition on silicone hydrogeland conventional hydrogel contact lens materials Contact Lens & Anterior Eye 2011;34, s21:

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

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

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

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

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

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

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

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

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

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, 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

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

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, 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

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

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

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

2008

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

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

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

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 lens materials Invest Ophthalmol Vis Sci 2007;48: E-abstract 5377

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

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

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