Khanal,S., Ngo,W., Nichols,K. K., Wilson,L., Barnes,S., Nichols,J. J. Human meibum and tear film derived (O-acyl)-omega-hydroxy fatty acids in meibomian gland dysfunction Ocular Surface 2021;21(July):118-128 [ Show Abstract ]

Purpose: The molecular basis of the tear film and lipid layer alterations in meibomian gland dysfunction (MGD) is unknown. This study aimed to identify and compare (O-acyl)-omega-hydroxy fatty acids (OAHFAs) derived from human meibum and tears in MGD. Methods: Of 195 eligible subjects (18–84 years, 62.6% female), 183 and 174 provided samples for tears and meibum, respectively. Subjects were classified into four groups: Normal, Asymptomatic MGD, MGD, and Mixed. Samples from the right eye of each subject were infused into the SCIEX 5600 TripleTOF mass spectrometer in negative ion mode. Lipid intensities identified with Analyst1.7 TF and SCIEX LipidView1.3 were normalized by an internal standard and total ion current, then statistically compared in MetaboAnalyst 4.0. Results: In meibum and tears, 76 and 78 unique OAHFAs were identified, respectively. The five most frequent and abundant OAHFAs were 18:2/16:2, 18:1/32:1, 18:1/30:1, 18:2/32:1, and 18:1/34:1. Two OAHFAs, 18:2/20:2 and 18:2/20:1, were identified only in tears. Initial univariate analysis revealed three differently regulated OAHFAs in meibum and eight in tears. Partial Least Square Discriminant Analysis showed 18:1/32:1, 18:2/16:2, 18:1/34:1 and 18:0/32:1 in tears, and 18:2/16:2, 18:1/32:1 and 18:2/32:2 in meibum, had variable importance in projection scores >1.5 and contributed the most to the separation of groups. In both meibum and tears, all OAHFAS except 18:2/16:2 were reduced in MGD compared to the normal group. Conclusion: MGD is accompanied by differential expression of specific OAHFAs in meibum and tears. These results suggest OAHFAs play a role in the altered biochemical profile of the tear film lipid layer in humans with MGD.

Klenkler,B., Sheardown,H., Jones,L. Growth factors in the tear film: Role in tissue maintenance, wound healing, and ocular pathology Ocular Surface 2007;5(3):228-239 [ Show Abstract ]

Numerous biologically active growth factors are secreted by the lacrimal gland and distributed via the tears over the ocular surface where they affect cellular proliferation, migration, differentiation, and survival. The role of growth factors and their receptors in maintenance of tissue homeostasis and wound healing continues to be elucidated, and the effect of growth factor imbalances In ocular surface diseases is just beginning to be understood. For Instance, in eyes with ocular surface diseases, Including conjunctivitis, corneal erosion, keratitis, and corneal ulcers, epidermal growth factor release rates have been shown to be significantly lower than in normal eyes during reflex tearing. Future research into the mechanisms of dry eye disease will focus on reasons for decreased tear and growth factor production in the neuronal reflex loop or the acinar lacrimal gland cells. Animal models to test therapeutic approaches must be developed. © 2007 Ethis Communications, Inc.

Kondela,T., Dushanov,E., Vorobyeva,M., Mamatkulov,K., Drolle,E., Soloviov,D., Hrubovcak,P., Kholmurodov,K., Arzumanyan,G., Leonenko,Z., Kucerka,N Investigating the competitive effects of cholesterol and melatonin in model lipid membranes Biochimica et Biophysica Acta - Biomembranes 2021;1863(9):183651 [ Show Abstract ]

We have studied the impact of cholesterol and/or melatonin on the static and dynamical properties of bilayers made of DPPC or DOPC utilizing neutron scattering techniques, Raman spectroscopy and molecular dynamics simulations. While differing in the amplitude of the effect due to cholesterol or melatonin when comparing their interactions with the two lipids, their addition ensued recognizable changes to both types of bilayers. As expected, based on the two-component systems of lipid/cholesterol or lipid/melatonin studied previously, we show the impact of cholesterol and melatonin being opposite and competitive in the case of three-component systems of lipid/cholesterol/melatonin. The effect of cholesterol appears to prevail over that of melatonin in the case of structural properties of DPPC-based bilayers, which can be explained by its interactions targeting primarily the saturated lipid chains. The dynamics of hydrocarbon chains represented by the ratio of trans/gauche conformers reveals the competitive effect of cholesterol and melatonin being somewhat more balanced. The additive yet opposing effects of cholesterol and melatonin have been observed also in the case of structural properties of DOPC-based bilayers. We report that cholesterol induced an increase in bilayer thickness, while melatonin induced a decrease in bilayer thickness in the three-component systems of DOPC/cholesterol/melatonin. Commensurately, by evaluating the projected area of DOPC, we demonstrate a lipid area decrease with an increasing concentration of cholesterol, and a lipid area increase with an increasing concentration of melatonin. The demonstrated condensing effect of cholesterol and the fluidizing effect of melatonin appear in an additive manner upon their mutual presence.

Korogiannaki,M., Guidi,G., Jones,L., Sheardown,H. Timolol maleate release from hyaluronic acid-containing model silicone hydrogel contact lens materials. J Biomat Appl 2015;30(3):361-376

Korogiannaki,M., Jones,L. W., Sheardown, H. The impact of a hyaluronic acid-grafted layer on the surface properties of model silicone hydrogel contact lenses Langmuir 2019;35(4):950-961 [ Show Abstract ]

The introduction of high oxygen transmissibility silicone hydrogel lenses ameliorated hypoxia-related complications, making them the most prescribed type of contact lens. Despite the progress made over the last two decades to improve their clinical performance, symptoms of ocular dryness and discomfort and a variety of adverse clinical events are still reported. Consequently, the rate of contact lens wear discontinuation has not been appreciably diminished by their introduction. Aiming to improve the interfacial interactions of silicone hydrogel contact lenses with the ocular surface, a biomimetic layer of the hydrophilic glycosaminoglycan hyaluronic acid (HA) (100 kDa), was covalently attached to the surface of model poly(2-hydroxyethyl methacrylate-co-3-methacryloxypropyl-tris-(trimethylsiloxy)silane) (pHEMA-co-TRIS) silicone hydrogel materials via UV-induced thiol-ene "click" chemistry. The surface structural changes after each modification step were studied by FTIR-ATR and XPS. Successful grafting of a homogenous HA layer to the surface of the model silicone hydrogels was confirmed by the consistent appearance of N (1s) and the significant decrease of the Si (2p) peaks, as determined by the low-resolution angle-resolved XPS. The HA-grafted surfaces demonstrated reduced contact angles, dehydration rate and nonspecific deposition of lysozyme and albumin, while maintaining their optical transparency (>90%). In vitro studies demonstrated that the HA-grafted pHEMA-co-TRIS materials did not show any toxicity to human corneal epithelial cells. These results suggest that surface immobilization of HA via thiol-ene "click" chemistry can be used as a promising surface treatment for silicone hydrogel contact lenses.

Laughton,D., Hill,J. S., McParland,M., Tasso,V., Woods,J., Zhu,X., Young,G., Craven,R., Hunt,C., Neitz,J., Neitz,M., Chalberg,T., Jones,D., Wolffsohn,J. Control of myopia using diffusion optics spectacle lenses: 4-year results of a multicentre randomised controlled, efficacy and safety study (CYPRESS) BMJ Open Ophthalmology 2024;9(1):e001790 [ Show Abstract ]

Aims To evaluate the myopia control efficacy of Diffusion Optics Technology (DOT) spectacle lenses in children over a 4-year treatment period.

Methods CYPRESS Part 1 (NCT03623074) was a 3-year multicentre, randomised, controlled, double-masked trial comparing two investigational spectacle lens DOT designs (Test 1, Test 2) and standard single vision Control lenses in 256 North American children aged 6–10 years. Children completing Part 1 (n=200) were invited to enrol in CYPRESS Part 2 (NCT04947735) for an additional 1-year period. In Part 2, Test 1 (n=35) and Control groups (n=42) continued with their original lens assignment and the Test 2 group (n=21) were crossed over to Test 1 (DOT 0.2) lenses. The co-primary endpoints were change from baseline in axial length (AL) and cycloplegic spherical equivalent refraction (cSER).

Results Test 1 spectacle lenses demonstrated superiority to the Control in both co-primary endpoints: with a difference between means (Test 1−Control) of −0.13 mm for AL (p=0.018) and 0.33 D for cSER (p=0.008) in Part 1 and −0.05 mm for AL (p=0.038) and 0.13 D for cSER (p=0.043) in Part 2. Comparing treatment effects in Part 1 and 2 suggests that COVID-19 public health restrictions negatively impacted treatment efficacy in study years 2 and 3.

Conclusion DOT 0.2 spectacle lenses are safe and effective at reducing myopia progression, with additional benefit evident in year 4 of wear. These results support the hypothesis that a mild reduction in retinal contrast can slow myopia progression in young children. The unprecedented disruption in participant schooling and lifestyle during the COVID-19 pandemic may have depressed treatment efficacy in Part 1.

Leat,S. J., Saraf,A., Rose,K., Christian,L. W., Irving,E. L., Jones, D. A., McCulloch, D. L. Measuring recognition visual acuity in young children–testability with the Waterloo Differential Acuity Test (WatDAT) Clinical and Experimental Optometry 2022;Online ahead of print [ Show Abstract ]

Clinical relevance: Visual acuity measurement is important for the detection and monitoring of eye disorders. Developing accurate and sensitive visual acuity tests suitable for young children is therefore desirable.

Background: Recognition or form visual acuity (VA), which is measured with matching in children aged 3 years and up, is more sensitive for detecting visual deficits compared to resolution VA. The Waterloo Differential Acuity Test (WatDAT) is a proposed recognition VA test using the concept of identifying the "odd one out" among distractors. The WatDAT is expected to be cognitively easier than matching tests and therefore may be used in younger children. The purpose of this study is to investigate the testability of the WatDAT paradigm in children aged 12-36 months, and to determine the optimum format and number of distractors.

Methods: Fifty-one typically-developing children aged 12-36 months participated in the study. Data for Patti Pics (PP) and Face targets (FT) were collected for formats with 3, 4 and 5 distractors. The targets were presented binocularly on a computer touch screen at 30 cm. The task was to touch the face among identical non-faces or a house among circles. Following initial training, there were 5 presentations for each distractor format. Testability was defined as correctly identifying at least 4/5 presentations and was also determined for uncrowded PP symbols using matching.

Results: Of participants aged 18-36 months, 87% could perform the WatDAT PP targets with 3 distractors compared to 68% for the FT, while 48% could perform matching with PP. The testability for FT increased to 85% for children ≥22 months. Younger children showed lower testability. For the 3 distractor format, PP targets gave 9% testability in children 12 to <18 months, and FT gave a testability of 16% in children 12 to <22 months.

Conclusion: WatDAT testability is higher than matching VA tests. This indicates that the newly developed WatDAT has potential for measuring recognition VA in children 18 months and older.

Leiske,D. L., Leiske,C. I., Leiske,D. R., Toney,M. F., Senchyna,M., Ketelson,H. A., Meadows,D. L., Srinivasan,S., Jones,L., Fuller,G. G. Temperature-induced transitions in the structure and interfacial rheology of human meibum Biophysical journal 2012;102(2):369-376 [ Show Abstract ]

Meibomian lipids are the primary component of the lipid layer of the tear film. Composed primarily of a mixture of lipids, meibum exhibits a range of melt temperatures. Compositional changes that occur with disease may alter the temperature at which meibum melts. Here we explore how the mechanical properties and structure of meibum from healthy subjects depend on temperature. Interfacial films of meibum were highly viscoelastic at 17°C, but as the films were heated to 30°C the surface moduli decreased by more than two orders of magnitude. Brewster angle microscopy revealed the presence of micron-scale inhomogeneities in meibum films at higher temperatures. Crystalline structure was probed by small angle x-ray scattering of bulk meibum, which showed evidence of a majority crystalline structure in all samples with lamellar spacing of 49 that melted at 34°C. A minority structure was observed in some samples with d-spacing at 110 that persisted up to 40°C. The melting of crystalline phases accompanied by a reduction in interfacial viscosity and elasticity has implications in meibum behavior in the tear film. If the melt temperature of meibum was altered significantly from disease-induced compositional changes, the resultant change in viscosity could alter secretion of lipids from meibomian glands, or tear-film stabilization properties of the lipid layer. © 2012 Biophysical Society.

Leiske,D. L., Miller,C. E., Rosenfeld,L., Cerretani,C., Ayzner,A., Lin,B., Meron,M., Senchyna,M., Ketelson,H. A., Meadows,D., Srinivasan,S., Jones,L., Radke,C. J., Toney,M. F., Fuller,G. G. Molecular structure of interfacial human meibum films Langmuir 2012;28(32):11858-11865

Liu,L. Y., Seo,J., McCanna,D. J., Subbaraman,L. N., Jones,L. W. Assessment of biofilm formation of E. meningoseptica, D. acidovorans, and S. maltophilia in lens cases and their growth on recovery media Contact Lens and Anterior Eye 2016;39(2):117-123 [ Show Abstract ]

Purpose: Bacterial biofilm formation in contact lens cases is a risk factor in the development of both microbial and infiltrative keratitis. This investigation evaluated three emerging pathogens: Stenotrophomonas maltophilia, Elizabethkingia meningoseptica, and Delftia acidovorans for biofilm formation and metabolic activity in lens cases. Also, growth of these bacteria on different media was assessed to optimize recovery conditions. Methods: The three bacteria were incubated in lens cases with different concentrations of tryptic soy broth. Biofilm formation was evaluated by measuring metabolic activity using MTT and enumerating the number of viable bacteria. To determine the optimal recovery media, dilutions of these microorganisms were plated on six different media. The number of colony forming units (CFU) was recorded after 48, 72, and 96 h of incubation at 32 °C and 37 °C for S. maltophilia, and at 37 °C for E. meningoseptica and D. acidovorans. Results: All three microorganisms established biofilms in the lens cases, with significant numbers of CFU recovered. Biofilms of S. maltophilia and E. meningoseptica were metabolically active. Significant reduction in metabolic activity and number of viable S. maltophilia occurred when the incubation temperature was raised from 32 °C to 37 °C (p < 0.05). The metabolic activity of the biofilms increased with greater organic load present. The highest percent recovery for all three organisms was given by Columbia blood agar, followed by chocolate. Conclusion: Based on the results, the presence of the three emerging pathogens present in lens cases and from corneal isolates can be accurately determined if proper growth media and incubation temperatures are utilized.

Liu,S., Chang,C. N., Verma,M. S., Hileeto,D., Muntz,A., Stahl,U., Woods,J., Jones,L. W., Gu,F. X. Phenylboronic acid modified mucoadhesive nanoparticle drug carriers facilitate weekly treatment of experimentallyinduced dry eye syndrome Nano Research 2015;8(2):621-635

Liu,S., Dozois,M. D., Chang,C. N., Ahmad,A., Ng,D. L. T., Hileeto,D., Liang,H., Reyad,M. -M, Boyd,S., Jones,L. W., Gu,F. X. Prolonged ocular retention of mucoadhesive nanoparticle eye drop formulation enables treatment of eye diseases using significantly reduced dosage Molecular Pharmaceutics 2016;13(9):2897-2905 [ Show Abstract ]

Eye diseases, such as dry eye syndrome, are commonly treated with eye drop formulations. However, eye drop formulations require frequent dosing with high drug concentrations due to poor ocular surface retention, which leads to poor patient compliance and high risks of side effects. We developed a mucoadhesive nanoparticle eye drop delivery platform to prolong the ocular retention of topical drugs, thus enabling treatment of eye diseases using reduced dosage. Using fluorescent imaging on rabbit eyes, we showed ocular retention of the fluorescent dye delivered through these nanoparticles beyond 24 h while free dyes were mostly cleared from the ocular surface within 3 h after administration. Utilizing the prolonged retention of the nanoparticles, we demonstrated effective treatment of experimentally induced dry eye in mice by delivering cyclosporin A (CsA) bound to this delivery system. The once a week dosing of 0.005 to 0.01% CsA in NP eye drop formulation demonstrated both the elimination of the inflammation signs and the recovery of ocular surface goblet cells after a month. Thrice daily administration of RESTASIS on mice only showed elimination without recovering the ocular surface goblet cells. The mucoadhesive nanoparticle eye drop platform demonstrated prolonged ocular surface retention and effective treatment of dry eye conditions with up to 50- to 100-fold reduction in overall dosage of CsA compared to RESTASIS, which may significantly reduce side effects and, by extending the interdosing interval, improve patient compliance. © 2016 American Chemical Society.

Liu,S., Jones,L., Gu,F. X. Development of Mucoadhesive Drug Delivery System Using Phenylboronic Acid Functionalized Poly(D,L-lactide)-b-Dextran Nanoparticles Macromolecular Bioscience 2012;12(12):1622-1626 [ Show Abstract ]

Mucoadhesive NP drug carriers have attracted substantial interest as a potential treatment for anterior eye diseases. NPs composed of PLA-Dex surface functionalized with a mucoadhesive ligand, PBA, were developed as drug carriers with particle sizes ranging from 25 to 28nm. Using CycA as a model drug, we showed that NPs encapsulated up to 13.7wt% CycA and exhibited sustained release for up to 5 d in vitro at a clinically relevant dose. We fine-tuned the PBA density on the NP surface to maximize the mucin-NP interaction without compromising the particle stability in vitro. This block copolymer conjugate may be useful to improve the bioavailability of topical formulations. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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.

Lorentz,H., Jones,L. Lipid deposition on hydrogel contact lenses: How history can help us today Optometry and Vision Science 2007;84(4):286-295 [ Show Abstract ]

The tear film is a complex fluid that is precisely maintained and which is essential to the health of the ocular surface. One of the major components of the tear film is lipid, which is produced by the meibomian glands and serves many important functions on the ocular surface. It is estimated that there are more than 45 individual lipids within the tear film, which vary greatly in their structure and properties. The composition of the lipid within the tear film has an enormous influence on the stability of the tear film, with a subsequent impact on the occurrence of dry eye and the ultimate success of contact lens wear. The purpose of this review article is to describe the composition of the tear film lipids and their interaction with contact lens materials, with a particular emphasis on how the chemistry of novel silicone hydrogel materials has resulted in clinicians needing to understand the deposition of lipids onto contact lenses and how they may best manage this complication.

Lorentz,H., Rogers,R., Jones,L. The impact of lipid on contact angle wettability Optometry and Vision Science 2007;84(10):946-953

Lourenco Nogueira,C., Boegel,S. C., Shukla,M., Ngo,W., Jones,L., Aucoin,M. G. Antiviral Activity of Contemporary Contact Lens Care Solutions against Two Human Seasonal Coronavirus Strains Pathogens 2022;11(4):472 [ Show Abstract ]

Background: Given that reports have suggested SARS-CoV-2 can be transmitted via conjunctiva, the ability of contact lens (CL) care products to reduce the infectiousness of two seasonal human coronavirus (HCoV) (HCoV-229E and HCoV-OC43) surrogates for SARS-CoV-2 was investigated.

Methods: Biotrue and Boston Simplus (Bausch&Lomb), OPTI-FREE Puremoist and Clear Care (Alcon), and cleadew and cleadew GP (Ophtecs) were tested. Their ability to inactivate HCoV was evaluated using contact times of 4 and 6 h as well as 1% and 10% of virus inoculum.

Results: Non-oxidative systems (Biotrue, Boston Simplus, and OPTI-FREE) did not exhibit a significant log10 reduction compared to controls for the two viral strains for either incubation time (all p > 0.05) when 10% tests were performed. For the 1% test, while Boston Simplus and OPTI-FREE exhibited a significant log10 reduction of both HCoV-229E (after 6 h) and HCoV-OC43 (after either 4 or 6 h incubation), those products showed less than 1 log10 reduction of the two infectious viruses. Oxidative systems based on hydrogen peroxide or povidone-iodine showed a significant log10 reduction compared with the controls for both HCoV-229E and HCoV-OC43 in all tested conditions (all p < 0.01). Clear Care led to virus inactivation to below the limit of quantification for tests performed with 1% of inoculum after 6 h incubation, while cleadew and cleadew GP led to inactivation of the two viruses to below the limit of quantification in all tested conditions.

Conclusion: Oxidative CL disinfection systems showed significant virucidal activity against HCoV-229E and HCoV-OC43, while non-oxidative systems showed minimal ability to inactivate the HCoV species examined.

Lourenco Nogueira,C., Boegel,S. C., Shukla,M., Ngo,W., Jones,L. Aucoin,M. G. The impact of a rub and rinse regimen on removal of human coronaviruses from contemporary contact lens materials Contact Lens Anterior Eye 2022;45(6):101719 [ Show Abstract ]

Purpose
To assess the influence of contemporary contact lens (CL) materials on human coronavirus attachment and the influence of a rub and rinse step to remove these viruses.

Methods
The binding rates of HCoV-229E and HCoV-OC43 to eight soft CL materials and four rigid gas permeable materials were analyzed. The impact of a rub and rinse step to remove these viruses from all materials was examined. The efficacy of Biotrue (Bausch & Lomb), OPTI-FREE Puremoist (Alcon), Clear Care (Alcon) and cleadew (Ophtecs) to remove virus contamination from two representative soft lens materials (etafilcon A and lotrafilcon B) was also determined.

Results
Approximately 102 to 103 infectious viral particles were recovered from each CL material. Although some materials were more prone to coronavirus adhesion, contamination of both viral types was reduced to below the limit of quantification (LQ) from all materials using a simple saline rinse step. Exposure to Clear Care and cleadew reduced the number of infectious viral particles from both etafilcon A and lotrafilcon B to below the LQ, while for Biotrue and OPTI-FREE Puremoist, infectious viral particles were reduced to below the LQ only when additional rub and rinse steps were included.

Conclusion
Human coronavirus contamination can be easily removed from CL surfaces. Although CL care products containing hydrogen peroxide and povidone-iodine efficiently removed virus contamination from CL surfaces without the need for a rub and rinse step, a full regimen including rub and rinse steps is crucial when using CL care products based on non-oxidative systems.

Lu,F., Simpson,T., Fonn,D., Sorbara,L., Jones,L. Validity of pachymetric measurements by manipulating the acoustic factor of Orbscan II Eye and Contact Lens 2006;32(2):78-83 [ Show Abstract ]

PURPOSE. To assess the validity of pachymetric measurements by examining the constancy of the acoustic factor (AF) of the Orbscan II (Orbtek, Bausch & Lomb, Rochester, NY) after overnight rigid gas-permeable (RGP) contact lens wear. METHODS. Twenty participants wore CRT (Paragon Vision Sciences, Mesa, AZ) HDS 100 contact lenses on one eye and control lenses on the contralateral eye for one night while sleeping. Another 24 participants wore CRT lenses on both eyes for one night. Central corneal thickness was measured using optical coherence tomography and Orbscan II on the night before lens use, immediately after lens removal on the following morning, and 1, 3, 6, and 12 hours later. By using optical coherence tomography as a reference, the adjusted AF was calculated by using a least squares method over time. RESULTS. The adjusted AF depended on the corneal thickness in normally hydrated corneas. The adjusted AF and the percentage change of the adjusted AF varied before and after overnight lens wear. There was a strong and significant correlation between the corneal swelling and the percentage change of the adjusted AF (all r at least 0.91, P<0.05). CONCLUSIONS. The adjusted AF is a variable, not a constant. The AF is a function of the corneal thickness and its alteration with, for example, corneal swelling. The validity of the adjusted Orbscan II pachymetric measures using a single AF is untenable. © 2006 Lippincott Williams & Wilkins, Inc.

Lu,F., Simpson,T., Sorbara,L., Fonn,D. The relationship between the treatment zone diameter and visual, optical and subjective performance in Corneal Refractive Therapy™ lens wearers Ophthalmic and Physiological Optics 2007;27(6):568-578 [ Show Abstract ]

Purpose: To investigate the stability of the treatment zone (TZ) size during Corneal Refractive Therapy (CRT™) over 4 weeks of lens wear, and to determine the relationship between TZ diameter and visual, optical and subjective performance. Methods: Twenty-three myopic subjects wore CRT™ lenses overnight and removed their lenses on awakening. Visual Acuity (VA), subjective vision, refractive error, aberrations and corneal topography were measured at baseline, immediately after lens removal on the first day and 14 h later, and these measurements were repeated on days 4, 10 and 28. The TZ including the central flattened zone (CFZ) and the annular steepened zone (ASZ) was demarcated by the change in corneal curvature from negative to positive and vice versa, using the tangential difference map from the Atlas corneal topographer. Results: After overnight CRT™ lens wear, the central cornea flattened and the mid-periphery steepened (both p < 0.001). After 4 weeks of lens wear, the CFZ (±SE) increased from 3.41 ± 0.09 mm on day 1 morning to 3.61 ± 0.07 mm on day 28 morning and the diameter of the ASZ increased from 8.17 ± 0.16 mm (day 1 morning) to 8.85 ± 0.14 mm (day 28 morning) (both p < 0.001). From day 10 onwards, the CFZ and ASZ diameter were stable in the morning (p ≥ 0.404). Throughout the day, the CFZ became smaller during the first 10 days (all p ≤ 0.022), whereas the ASZ diameter remained constant (all p ≥ 0.079). There were positive correlations between the CFZ or ASZ and residual refractive error, subjective vision and spherical aberration. The CFZ was also correlated with astigmatism and higher order aberrations, and the ASZ was positively correlated with coma (r = 0.726 to 0.961, all p ≤ 0.042). In addition, there were negative correlations between the CFZ or ASZ and total aberration and defocus and between the ASZ and VA (r = -0.707 to -0.953, all p ≤ 0.050). Conclusion: The TZ changed during the first 10 days. Its size was associated with VA, residual refractive error, aberrations and subjective vision. The concept of a TZ is a useful metric of visual, optical and subjective performance in CRT™ lens wearers. © 2007 The Authors.

Lu,F., Simpson,T., Sorbara,L., Fonn,D. Corneal Refractive Therapy™ with different lens materials, Part 2: Effect of oxygen transmissibility on corneal shape and optical characteristics Optometry and Vision Science 2007;84(4):349-356 [ Show Abstract ]

PURPOSE. To compare the effects of two different oxygen transmissible (Dk/t) lenses on corneal shape and optical performance after one night of corneal refractive therapy (CRT®) for myopia. METHODS. Twenty myopic subjects were fit with Menicon Z (MZ) (Dk/t = 90.6, Paragon CRT® lenses) on one eye and an Equalens II (EII) CRT® lens (Dk/t = 47.2) on the contralateral eye (eye randomized). Corneal topography, refractive error and aberrations were measured before lens insertion (baseline), and the following day after overnight lens wear, on lens removal and 1, 3, 6, 12 h later. Root mean square wavefront errors were measured using 4.5 mm pupils. RESULTS. Averaged over position and time, the horizontal corneal curvature was statistically different between the MZ and EII lens-wearing eyes (p = 0.011). The central cornea flattened similarly (p = 0.886) and the mid-periphery steepened in both eyes (p = 0.061) from baseline. The EII lens-wearing eyes were steeper in the mid-periphery than the MZ eyes immediately after lens removal and at the 1-h visit (p ≤ 0.032). Central corneal flattening and mid-peripheral corneal steepening regressed over time (all p < 0.001) but did not recover to baseline by 12 h (all p < 0.004). Myopia was reduced equally by 0.84 ± 0.83 D for the MZ-lens wearing eyes and 0.84 ± 0.87 D for the EII eyes (p = 0.969). Coma increased from baseline 1.85X (0.056 ± 0.081 μm) for the MZ-lens wearing eyes and 1.72X (0.048 ± 0.084 μm) for the EII eyes (both p < 0.001). Spherical aberration increased from baseline 4.55X (0.101 ± 0.077 μm) for the MZ-lens wearing eyes and 4.31X (0.085 ± 0.076 μm) for the EII eyes (both p < 0.001), but there were no differences between the MZ and EII eyes (all p ≥ 0.308). Coma and spherical aberration did not return to baseline by 12 h (both p ≤ 0.007). CONCLUSIONS. After one night of CRT® lens wear, changes in corneal shape were slightly different, with more mid-peripheral steepening in the EII eyes compared to the MZ eyes. Change in central corneal curvature and optical performance were similar in both eyes. © 2007 American Academy of Optometry.

Lu,F., Simpson,T., Sorbara,L., Fonn,D. Malleability of the ocular surface in response to mechanical stress induced by orthokeratology contact lenses Cornea 2008;27(2):133-141 [ Show Abstract ]

PURPOSE: To determine the malleability of the ocular surface by examining the acute effects of local mechanical stress on optical performance, corneal shape, and corneal/epithelial thickness after corneal refractive therapy for myopia and hyperopia (CRT and CRTH). METHODS: Twenty ametropes (spherical equivalent: -2.08 ± 2.31 D) wore CRT and CRTH lenses in a random order on 1 eye (randomly selected). The lenses were worn for 15, 30, and 60 minutes (randomly ordered, with each period taking place on a different day). Refractive error, aberrations, corneal topography, and corneal/epithelial thickness (using OCT) were measured before and after lens wear. The measurements were performed on the control eyes at the 60-minute visit only. RESULTS: With both CRT and CRTH lens wear, significant changes occurred in many parameters from the 15-minute time point. The refractive error and defocus decreased after CRT lens wear (all P 0.05). Higher-order aberrations, including coma and spherical aberration (SA), increased after CRT and CRTH lens wear (all P 0.05). Higher-order aberrations, including coma and spherical aberration (SA), increased after CRT and CRTH lens wear (all P 0.05). Higher-order aberrations, including coma and spherical aberration (SA), increased after CRT and CRTH lens wear (all P 0.05). Higher-order aberrations, including coma and spherical aberration (SA), increased after CRT and CRTH lens wear (all P 0.05). Higher-order aberrations, including coma and spherical aberration (SA), increased after CRT and CRTH lens wear (all P 0.05). Higher-order aberrations, including coma and spherical aberration (SA), increased after CRT and CRTH lens wear (all P 0.05). Higher-order aberrations, including coma and spherical aberration (SA), increased after CRT and CRTH lens wear (all P 0.05). CONCLUSIONS: CRT lenses for myopia and hyperopia induce significant structural and optical changes in as little as 15 minutes. The cornea, particularly the epithelium, is remarkably malleable, with rapid steepening and flattening possible in little time. © 2008 Lippincott Williams & Wilkins, Inc.