Scientific Presentations


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.

Luensmann D, van Doorn K, May C, Srinivasan S, Jones L. Physical Dimension and Optical Assessment of Currently Marketed Silicone Hydrogel Contact Lenses After Exposure to Cosmetics American Academy of Optometry, San Antonio, USA, 2018 [ Show Abstract ][ PDF ]

Purpose: Contact lens wearers may inadvertently expose their lenses during the lens insertion and removal process or while wearing their lenses to cosmetic products being used. This study investigated the impact of various cosmetics on the physical dimension and optical properties of three recently marketed silicone hydrogel contact lenses.

Methods: In this in-vitro study, senofilcon C, samfilcon A, and lotrafilcon B+EOBO (polyoxyethylene-polyoxybutylene) were individually coated with cosmetic products followed by a 1-hour soak in phosphate-buffered saline. Cosmetic products included; 3 hand creams (HC1: Glysomed; HC2: Vaseline Healthy Hand & Nail Conditioning; HC3: Intense Relieve), 3 make-up removers (MR1: Lid-Care Towelettes; MR2: Gentle waterproof eye and Lip Makeup Remover; MR3: Oil-Free Makeup Remover), and 3 mascaras (MA1: Great Lash – waterproof; MA2: Wonder’Lash – waterproof, MA3: Voluminous Original). Lens diameter, sagittal depth, and base curve were measured using the Chiltern (Optimec Limited), while lens power and optical quality were assessed using the Contest Plus II (Rotlex) (n=6 for each lens/ cosmetic combination). The impact of cosmetics was tested between lenses and compared to baseline (uncoated control lenses).

Results: For lens diameter, makeup removers (MR2 & MR3) had the largest impact, with an increase of up to 0.27mm (MR2) and 0.36mm (MR3) for senofilcon C and samfilcon A respectively (p<0.01 compared to baseline), while lotrafilcon B+EOBO showed a decrease of only 0.01mm (p<0.01 between lens types). For sagittal depth, mascara MA1 had the greatest impact, followed by makeup removers MR2 & MR3. All lenses had increases in sagittal depth after MA1 exposure (0.16±0.06mm in lotrafilcon B+EOBO, 0.24±0.22 mm and 0.26±0.09mm in samfilcon A and senofilcon C respectively; p<0.01 for all lenses compared to baseline). For base curve, the makeup removers (MR2 & MR3) caused increases for both senofilcon C (up to 0.36mm) and samfilcon A (up to 0.45mm), but lotrafilcon B+EOBO was unaffected. Lens power changes were generally minor (less than 0.25D). However, senofilcon C had a significant increase 1.19±0.65D more minus after MA1 exposure (p<0.001). Image quality was most effected by mascaras, although given that all lens types were adversely affected to similar degrees, none of the lenses performed better or worse after mascara application (p>0.05). Hand creams had no effect on any variable investigated for any lens material.

Conclusion: Overall, mascara MA1 and make-up removers MR2 & MR3 had the largest affect on lens dimensions, and mascara MA1 had the largest affect on optical lens properties. Some dimensional changes were outside of the ISO tolerance, which could affect lens fit. Lotrafilcon B+EOBO lenses were generally least affected by these cosmetic products.

Marx S, Kwan J, Jones-Jordan L, Powell D, Srinivasan S, Sickenberger W, Jones J, Pucker A. Degree of Meibomian Gland Tortuosity in Successful Soft Contact Lens Wearers and Dropouts American Academy of Optometry, San Antonio, USA, 2018 [ Show Abstract ]

Purpose: The etiology of meibomian gland (MG) tortuosity (deviated glands) is unknown, but it may be caused by chronic terminal duct obstruction or by genetic predisposition. The study purpose was to determine if MG tortuosity impacts successful contact lens (CL) wear and if degree of tortuosity was associated with other signs or symptoms of ocular dryness.

Methods: This five-site case-control study recruited subjects between 18 and 45 years of age. Cases had ceased CL use within the past 6-12 months due to discomfort, while age- and sex-matched controls were able to comfortably wear CLs for ≥8 hours/day for ≥5 days/week. Each subject was administered a study-specific CL questionnaire and a SPEED questionnaire. Clinical testing included non-invasive tear break-up time (NITBUT), tear meniscus height (TMH), MG expressibility, meibum quality, and meibography (OCULUS Keratograph 5M). MG tortuosity for each eyelid was graded using the 5-point Halleran scale (Grade 0: no tortuosity; Grade 4: ≥75% of visible MG being tortuous). Worse eyes (determined by worse eye for tortuosity) comparisons were made with paired t-tests (means) or McNemar’s test (frequencies).

Results: Fifty-six matched-pairs were recruited across sites. The mean ± SD age of the cases (28.5 ± 7.1 years) and controls (28.6 ± 7.0 years) were not significantly different (p = 0.66). The cases had significantly higher SPEED scores than the controls (6.42 ± 4.96 vs. 2.62 ± 2.66; p < 0.001). Cases did not have significantly higher upper (2.13 ± 1.09 vs. 1.80 ± 0.96; p = 0.07), lower (0.82 ± 0.64 vs. 1.00 ± 0.74; p = 0.12) or total (2.97 ± 1.30 vs. 2.80 ± 1.29; p = 0.39) eyelid tortuosity scores than controls. Tortuosity was significantly associated with TMH (p = 0.02), MG expressibility of upper (p = 0.03) and lower eyelids (p = 0.01) but not SPEED, NITBUT, meibum quality, or MG atrophy (all p ≥ 0.14).

Conclusion: At least some degree of MG tortuosity was commonly noted in both groups of subjects in the upper and lower eyelids. While tortuosity may not be a risk factor for CL dropout, tortuosity is likely a sign of decreased MG health. Tortuosity may result in altered tear lipid production, which could result in decreased meibum expressibility and reduced tear volume noted in this study.

Mohammadi S, Jones L, Gorbet M. Investigation of Latanoprost Release from Contact Lens Materials in the presence of cells and under in vitro Tear Replenishment Invest Ophthalmol Vis Sci 2018;E-Abstract 1770 [ Show Abstract ]

Purpose: To effectively mimic the ocular environment for biocompatibility and drug delivery studies, the limited volume and replenishment of the tear film and the presence of cells should be considered. By using an in vitro corneal epithelial cell model combined with a tear replenishment (TR) method, this study aimed to investigate the delivery of Latanoprost by commercially available contact lenses (CL) and compare the dynamic release results to non-replenished (immersion) conditions.

Methods: To enable in vitro “lens wear”, cell culture inserts were formed to recreate the geometry of the cornea prior to seeding of human corneal epithelial cells. The curved cornea models (CCMs) were ready after 7 and 14 days for mono-layer and stratified models respectively. The in vitro TR was achieved via intermittent flow of a tear solution analogue over the CCMs at a rate of 1mL/hour. Three CLs (balafilcon A; senofilcon A; etafilcon A), were soaked for 24hrs in the glaucoma drug, Latanoprost, at concentrations of 123 µg/mL (high doping; HD) and 9.5 µg/mL (low doping; LD). Lenses were then onlayed on the CCMs (n=3) and drug concentration was determined on the basal (diffusion/transport) and apical (supernatant) sides after 1, 4, 8 and 12hrs.

Results: A zero-order kinetic was observed for basal drug concentration over the 12hr period. The drug release and diffusion through the CCMs was significantly higher in etafilcon A (p<0.001). Also for HD lenses, the overall release was comparable to the prescribed daily dose. The apical release of the drug was significantly lower for replenished vs. immersed CCMs (p<0.001) in HD lenses. In contrast to stratified CCMs, cell viability was significantly lower under replenished conditions compared to immersed mono-layer CCMs (p=0.002). The release ratio of HD to LD lenses were in agreement to the doping ratio.

Conclusions: The Latanoprost release studies under dynamic conditions further confirmed the significant role that cells play in the release of that drug from a CL material. These results also demonstrated yet another important role that a dynamic release model will have in predicting the amount of drug that can be absorbed through the cornea or lost from a CL into the tear film/lacrimal system. Recreating the microfluidics of the TR in vitro can contribute to a better understanding of interactions between the ocular surface and drug-delivery CL.

Powell D, Jones-Jordan L, Srinivasan S, Kwan J, Marx S, Sickenberger W, Jones L, Pucker A. Impact of Soft Contact Lens Factors and Compliance on Contact Lens Dropout American Academy of Optometry, San Antonio, USA, 2018 [ Show Abstract ]

Purpose: To determine if certain contact lens (CL) factors or compliance issues may contribute to CL dropout (CLD).

Methods: Subjects 18-45 years of age who had dropped out of soft CL wear (cases) within the past 6-12 months due to discomfort were enrolled across five study sites. Cases were compared to age- and sex-matched successful soft CL-wearing controls (CLDEQ-8 score ≤ 10). Each subject was administered a study-specific questionnaire containing items that queried CL history and compliance: Age at first CL wear; number of years, days/week and hours/day of wear; primary CL solution used (multipurpose vs. hydrogen peroxide); lens material (conventional vs. silicone hydrogel) and modality (daily disposable/biweekly/monthly replacement); napping/overnight sleeping in CLs, and routine exposure of the lens case or CLs to tap water. Comparisons were made using paired t-tests and McNemar’s tests for means and frequencies, respectively.

Results: Fifty-six matched-pairs completed the one-visit study. Mean age (± SD) of cases and controls were 28.5 ± 7.1 and 28.6 ± 7.0 years, respectively (p = 0.66). There was no difference in the age at first CL wear (p = 0.19), although controls had worn CLs nearly 3 years longer overall than cases (p = 0.01). Over two-thirds of cases reported wearing their CLs ≤ 4 days/week before dropping out of CLs while nearly the same proportion of controls wore their CLs 6-7 days/week (p < 0.001). Cases also had a shorter average wear time by at least 2 hours/day when compared to controls (p < 0.001). Lens modality, primary CL solution used, CL or case exposure to tap water, on-time CL replacement, case replacement at least every 3 months, sleeping in CLs, or wearing a pair CLs beyond the clinician-recommended timeframe were not associated with CLD (all p ≥ 0.41). Although borderline significant, the odds of controls having worn a conventional hydrogel CL was higher than that for cases (OR = 2.5, p = 0.05). Controls napped more often in their CLs than cases (p = 0.01).

Conclusion: Successful soft CL wearers are more likely to wear their lenses on or nearly every day of the week and for more hours each day than those who eventually dropped out of soft CL wear due to discomfort. The material that comprises a soft CL may factor into CLD. CL compliance within this cohort does not appear to be associated with CLD.

Pucker A, Jones-Jordan L, Srinivasan S, Powell D, Kwan J, Marx S, Sickenberger W, Jones L. Association Between Meibomian Gland Health and Soft Contact Lens Dropout American Academy of Optometry, San Antonio, USA, 2018 [ Show Abstract ]

Purpose: There is virtually no growth in the global contact lens (CL) market because there are as many CL dropouts as new CL wearers. The purpose of this study was to determine if meibomian gland (MG) atrophy has an impact on successful CL wear.
Methods: This five-site study recruited subjects between the ages of 18 and 45 years who had discontinued CL use within the past 6-12 months due to discomfort. CL dropout subjects (cases) were compared to age- and sex-matched successful CL wearing controls (≥8 hours/day for ≥5 days/week). Each subject was administered a study-specific CL questionnaire and a standard SPEED questionnaire. Clinical testing included non-invasive tear break-up time (NITBUT), tear meniscus height (TMH), meibomian gland function (expression and plugging), and meibography (OCULUS Keratograph 5M). MG atrophy was graded subjectively on a 0 to 3 scale by eyelid for each eye; atrophy was categorized as significant if the upper or lower eyelid grade was ≥ 2 or the total grade for both upper and lower eyelids was ≥ 4. Subjects were considered to have diagnosed dry eye if they had a SPEED score > 5.0 and a positive NITBUT (< 10 s) or TMH (< 0.2 mm) test. Worse eye comparisons were made with paired t-tests (means) or McNemar’s test (frequencies).
Results: 56 matched-pairs were recruited across sites. The mean ± SD age of the cases (28.5 ± 7.1 years) and controls (28.6 ± 7.0 years) were similar (p = 0.66). Cases had significantly higher SPEED scores than controls (6.4 ± 5.0 vs. 2.6 ± 2.7; p < 0.0001). Diagnosed dry eye was significantly associated with CL dropout (p < 0.001). NITBUT, TMH, and significant upper, lower and total MG atrophy was not different between groups (all p ≥ 0.16). Upper (p < 0.001) and lower (p = 0.002) MG plugging and upper (p < 0.001) but not lower (p = 0.11) meibum quality were associated with CL dropout. Neither upper nor lower MG atrophy were associated with upper or lower MG plugging or upper or lower meibum quality (all p ≥ 0.35).
Conclusion: CL dropout may be precipitated by underlying dry eye, though most dry eye signs, with the exception of MG function, have minimal predictive value for CL dropout. Nevertheless, evidence from this study suggests that practitioners should screen for and educate CL patients about the importance of eyelid hygiene in order to maintain comfortable CL use.

Pucker A, Jordan L, Srinivasan S, Powell D, Kwan J, Marx S, Sickenberger W, Jones L. Is Compliance and Ocular Surface Factors Associated with Contact Lens Dropout? Invest Ophthalmol Vis Sci 2018;E-Abstract 3933 [ Show Abstract ]

Purpose: Discontinuation from contact lens (CL) wear is estimated to be approximately equal to the numbers of new wearers per year, resulting in virtually no growth in the global CL market. The purpose of this study was to determine factors associated with successful wear that may impact CL dropout.

Methods: This five-site study recruited subjects 18-45 years of age who had ceased CL wear within the past 6-12 months due to discomfort. Dropout subjects were compared to age- and sex-matched successful CL wearers (≥8 hours/day for ≥5 days/week). Each subject was administered a study-specific questionnaire that queried general CL history and compliance. Clinical testing included non-invasive tear break-up time and tear meniscus height (OCULUS Keratograph 5M), blepharitis assessment, and meibum quality and expression. Comparisons were made with paired t-tests for means or McNemar’s test for agreement for frequencies.

Results; 25 matched-pairs (50 total subjects) were recruited across sites. The mean ± SD age of the subjects were 28.6 ± 7.1 years (range = 18 to 44); the sample was 73.7% female. Successful CL wearers had worn CLs for 10.6 ± 5.5 years while CL dropouts had worn CLs for 6.8 ± 5.9 years (p = 0.03). CL dropout was not associated with exposing CLs to tap water (p = 1.00), replacing CLs on time (p = 0.99), replacing their CL case at least every 3 months (p = 0.73), sleeping in CLs (p = 0.32), or wearing CLs longer than their clinician recommended (p = 1.00); current CL wearers, however, napped more frequently in their CLs (p = 0.03). Non-invasive tear break-up time (p = 0.19), tear meniscus height (p = 0.33), upper (p = 0.27) and lower (p = 0.26) eyelid blepharitis, lower eyelid meibum quality (p = 0.92) and lower eyelid meibum expressibility (p = 0.33) were also not associated with CL dropout; nevertheless, upper eyelid meibum quality (p = 0.03) and expressibility (p = 0.002) were associated with CL dropout.

Conclusions: CL compliance does not appear to be associated with CL dropout, but this study did collect some evidence indicating that decreased meibomian gland function may reduce one’s ability to successfully wear CLs. These data support the need for early meibomian gland dysfunction prevention and treatment because interventions may promote better long-term ocular health and the ability to comfortably wear CLs.

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.

Sivak A, Srinivasan S, Walsh K, Haines L, MacIver S, Killeen R, Nakhla N, Jones L. Professional Collaboration for Patient-Centred Eye Care – A Continuing Education Program for Optometrists and Pharmacists American Academy of Optometry, San Antonio, USA, 2018 [ Show Abstract ][ PDF ]

SIGNIFICANCE: Collaboration between North American pharmacists and optometrists is inconsistent, despite overlapping goals and concerns relating to eye care.
PURPOSE: The Centre for Ocular Research & Education (CORE), School of Optometry & Vision Science and School of Pharmacy at the University of Waterloo (UW) collaborated to address this gap in information sharing by developing a series of web-based multimedia continuing education modules directed at pharmacists, optometrists and optometric assistants. These modules were designed to highlight unique and overlapping spheres of knowledge in addition to providing guidance with respect to developing a plan for interprofessional collaboration.
METHODS: Content was developed through interprofessional discussion and by consulting emerging research, evidence-based guidelines and needs assessments, and was informed by the Canadian Interprofessional Health Collaborative competency framework. The UW Centre for Extended Learning provided guidance with respect to instructional design and usability. Content was reviewed by community-based optometrists and pharmacists as well as external content matter experts representing both professions. The modules were reviewed and accredited by the Council on Optometric Practitioner Education (COPE) and the Canadian Council on Continuing Education in Pharmacy (CCCEP).
RESULTS: The completed program includes four hours of content comprising four modules: (1) an overview of interprofessional collaboration, (2) contact lens care systems, (3) management of dry eye disease, and (4) contact lens red eye. Each module includes profession-specific perspectives, guidelines related to ocular needs and treatment options, and profession-specific roles in addressing patient needs. Modules also outline topic-specific opportunities for communication, collaboration and referral.
CONCLUSIONS: Opportunities for collaboration between optometrists and pharmacists are rich but largely unexplored within the confines of profession-specific “tunnel vision.” These CE modules aim to start a conversation about the ways in which optometrists and pharmacists can work together to enhance patient-focused care.

Sivak A, Woods J, Srinivasan S, Subbaraman L, Jones L. The Centre for Ocular Research & Education American Academy of Optometry, San Antonio, USA, 2018 [ Show Abstract ]

The Centre for Ocular Research & Education (CORE) at the University of Waterloo, Canada has been conducting ocular research for over 30 years (formerly as the Centre for Contact Lens Research), and has been involved in some of the most meaningful advances in eye and contact lens research. CORE seamlessly integrates clinical observations and educational materials with insights grounded in basic bioscience. The CORE team has the experience, technology and regulatory framework to support fundamental and clinical research focusing on pharmaceuticals, biomaterials (including contact lenses), ocular physiology and imaging.

CORE’s biosciences team has the expertise to analyze biological samples; engineer novel biomaterials; test product biocompatibility; analyze contact lens materials; develop in vitro models; test lens care systems for antimicrobial efficacy and cytotoxicity; analyze proteins, lipids and inflammatory markers; evaluate, analyze and identify bacteria and biofilms; and test the viability of ocular surface cells.

CORE’s clinical team has the capacity to execute all stages of study development, from protocol design through report generation for clinical research and Phase II, III and IV clinical trials. Features include specialized imaging and image analysis; resources for coordinating multi-site clinical trials; staff trained to collect patient and practitioner perspectives via focus groups, interview and web-based surveys; dedicated in-house teams dedicated to regulatory oversight, data analysis and subject recruitment.

Over the years, CORE’s team has published hundreds of peer-reviewed publications, presented results at scientific conferences and meetings around the world, and lent its expertise to a variety of scientific panels and associations. In addition to providing training for post-graduates and industry teams, CORE is committed to sharing its observations and knowledge with eye care professionals worldwide via web-based resources, information sheets and posters, conventional print articles, continuing education seminars, conference reports, user manuals and fitting guides and instructional videos.

Srinivasan S, Caffery B, Harthan J, Acs M, Barnett M, Johnson-Tong L, Papinski D, Pemberton B. Prevalence of Meibomian Gland Dysfunction in Sjogren’s Syndrome Patients Invest Ophthalmol Vis Sci 2018;E-Abstract 921

Subbaraman L, Dare E, Fung CK, McCanna D, Jones L. Establishment of optimal culture media in human corneal epithelial wound healing models Invest Ophthalmol Vis Sci 2018;E-Abstract 4337 [ Show Abstract ]

Purpose: Damage to the human corneal epithelium can potentially result in severe vision loss. Corneal epithelial cell damage should be quickly repaired to prevent infection and adequate wound healing is required for corneal transplants and recovery from LASIK surgery. To study corneal epithelial wound healing, an in vitro scratch model and an in vitro exclusion zone model are often used. The purpose of this study was to establish the optimum media to use as a control solution in wound healing models.

Methods: Immortalized human corneal epithelial cells were cultured in different growth media. A scratch wound was made on the epithelial cell monolayers and cell recovery was followed for up to 48 hours by measuring the area of the wound. The effect of normoxic and hypoxic conditions on tight junctional integrity and metabolic activity of cells grown in different growth media were also investigated. Using an exclusion zone model, the degree of cell proliferation into the exclusion zone was determined after seven and nine days of growth in cell culture media.

Results: Wound healing with Dulbecco’s Modified Eagle Medium: Nutrient mixture F-12 (DMEM/F-12) was significantly faster than both the keratinocyte serum-free medium (KSFM) (p<0.05) and EpiLife (p<0.05) 10 hours after wounding using the scratch model and nine days after wounding using the exclusion zone technique (p<0.05). In addition, hypoxic culture significantly delayed wound healing by an average of 32.4%. In the culture media DMEM/F-12, human corneal epithelial cells stained for abundant zona occludens-1 (ZO-1), connexion 43 (Cx43) and had a high metabolic activity indicating significant epithelial barrier formation, gap junction formation and high cell viability.

Conclusions: DMEM/F-12 led to superior wound healing under hypoxic and normoxic conditions and in two different wound healing models. DMEM/F-12 appears to be the optimum wound healing control for corneal wound healing models due to superior metabolic activity, wound healing and formation of a greater number of tight junctional proteins in cells grown in this medium over the other media tested.

Varikooty J, Woods J, Lumb E. Validation of Multifocal Soft Lens Power Calculator in OptiExpert Application for Clariti 1-Day Multifocal Lens Fitting American Academy of Optometry, San Antonio, USA, 2018 [ Show Abstract ][ PDF ]

Purpose: The multifocal soft lens calculator component of the OptiExpert-multifunctional app was developed by CooperVision Inc to make multifocal CL fitting easy, by predicting the required powers for clariti-1 day multifocal (C1DM) from the spectacle prescription, in a presbyopic population. This retrospective data analysis was conducted to validate the software.

Methods: The data used for validation came from a sample of 26 subjects, whose subjective refraction data (sph, cyl, add, ocular dominance) was already determined and C1DM had already been fit and dispensed according to clinical assessments using the C1DM fitting guide. After 3-10 days all subjects attended a power optimization visit where the contact lens (CL) power was re-assessed and, if required, a new prescription was dispensed. The subjective refraction data was subsequently entered in the OptiExpert app, and the recommended CL power for each eye (OptiExpert-Rx) was compared to the power dispensed after the optimization visit (Optimized-Rx). Correlation analysis was conducted between OptiExpert-Rx and Optimized-Rx. A Bland-Altman analysis comparison was also conducted to measure agreement between methods.

Results: The 26 presbyopes (21 female, 5 male) had a mean (±SD) age of 56.7 (±7.4) years. Subjective refraction range across all 52 eyes was +5.00 to -6.00 D sph with ≤ -1.00 D cyl. The reading add ranged between +1.50 to +2.50 D. 96% (25) of the subjects were successfully fit in the initial trial with the first pair of C1DM CLs, and the remaining 1 subject required 2 pairs of CLs. At the optimization visit a few days later, only 10% of eyes (5 eyes across 4 subjects) required a change in lens power, meaning 100% of eyes were successfully fit with just 1 additional lens. In subjective responses, 92% reported that C1DM CLs met or exceeded their visual needs. The suggested OptiExpert-Rx was significantly correlated with Optimized-Rx (r ≥ 0.996 and p <0.0001). Bland Altman analysis showed a mean difference (and 95% limits of agreement) between OptiExpert-Rx and Optimized-Rx of 0.09 D (-0.64 to +0.46). Compared to the final optimized lens powers, over 80% of eyes were within 0.25DS of the predicted power using OptiExpert.

Conclusion: The clariti-1 day multifocal powers recommended by the OptiExpert app were in close agreement with investigator determined CL powers. Given this high level of agreement, OptiExpert multifocal soft lens calculator can be confidently used as a clinical tool to aid clariti-1 day multifocal fitting success, potentially saving valuable chair time.

Woods J, Moezzi A, Varikooty J, Jones L. Comparison of lens orientation stability of two daily disposable silicone hydrogel toric lenses Contact Lens & Anterior Eye 2018;41, Supp 1:S93

Woods J, Ng AY, Luensmann D, Guthrie S, Jones L. Short-term comfort comparison of two daily disposable contact lenses of different material and modulus Invest Ophthalmol Vis Sci 2018;E-Abstract 1753 [ Show Abstract ][ PDF ]

Purpose: Daily disposable contact lenses (DDs) are now widely available in both silicone hydrogel (SH) and hydrogel (H) materials. The higher oxygen transmissibility of SH materials provides many benefits, but their higher modulus has been linked with reduced lens comfort compared to H lenses. This randomized, double-masked clinical trial assessed the short-term comfort of two DDs of differing modulus, yet similar water content (WC): a SH-DD (somofilcon A; clariti® 1 day; CooperVision; 0.50MPa modulus, 56% WC) and a H-DD (etafilcon A; 1-Day Acuvue® Moist®; Johnson & Johnson; 0.29MPa modulus, 57% WC).

Methods: 120 subjects wore the lenses contralaterally, over one day. Targeted recruitment meant that 60 subjects were habitual H-DD wearers (all adapted wearers of 1-Day Acuvue Moist), 60 were non-DD habitual wearers (adapted to various SH and H re-usable lenses). Subjects rated lens comfort on a 0-100 integer scale (100= cannot be felt) at insertion and then hourly until 8hrs. Of particular interest was the comfort at the beginning and end of the 8hr wear period and these data points were tested for equivalence. At the final visit subjects were asked for their lens preference, based on comfort.

Results: Mean subjective comfort was not different between SH-DD and H-DD across the wear period (p>0.05), on insertion (87±14 SH-DD vs 89±14 H-DD; p>0.05) or after 8hrs (82±18 SH-DD vs 83±17 H-DD; p>0.05). Based on equivalency margins of ±5-points, the study lenses showed equivalent comfort at insertion (p=0.03) and at 8hrs (p=0.001). Both lenses exhibited a significant reduction in comfort over the 8hr period (both p<0.001). When subjects’ data was divided according to their habitual lens modality groups (60 H-DD wearers and 60 re-useable wearers), there were also no comfort differences between the study lenses, either across time, or at insertion and 8hrs (all p>0.05). Lens preference was not different between lenses at dispensing or at the final visit (both p>0.05).

Conclusions: Initial and 8hr comfort were not compromised with the SH-DD compared to the H-DD, despite its higher modulus, and there was no difference in the lens preference distribution. The results suggest that lower comfort should not be anticipated when fitting SH-DDs of an appropriate design, thus allowing other material properties such as high oxygen permeability to be considered.

Woods J, Ng AY, Luensmann D, Jones L. Short-term comfort comparison of a low modulus hydrogel vs a higher modulus silicone hydrogel daily disposable lens Contact Lens & Anterior Eye 2018;41, Supp 1:S42

Woods J, Panjwani F, Papinski D, Varikooty J, Jones L. In-vivo dehydration comparison of omafilcon A and stenfilcon A with delefilcon A Contact Lens & Anterior Eye 2018;41, Supp 1:S41

Yee A, Jabeen A, Subbaraman L, McCanna D, Phan C-M, Jones L. Novel In-Vitro Method to Study Bacterial Interaction with Contact Lenses American Academy of Optometry, San Antonio, USA, 2018 [ Show Abstract ][ PDF ]

Purpose: Previous in-vitro studies have used a “soak” or closed vial method to assess bacterial binding to contact lenses (CL). The purpose of this study was to develop a novel in-vitro drip model to determine if bacterial adhesion to a CL material was possible. The novel in-vitro drip model would more closely resemble an accurate eye model in comparison to current methods undertaken.

Methods: The novel in-vitro drip method consists of a 5.5 mL syringe with saline solution and a flow rate controller dispensing 5 µl of saline solution containing the bacteria. The consistent drip volume is adjustable and mimics the normal human tear volume and flow. The solution flows through a silicone tube and onto a CL. The CL was placed on a sterile glass eyeball in an enclosed container to maintain the environment’s humidity. In the soak method, the CL was placed on top of a sterile glass eyeball and placed in the enclosed container with a 5 mL saline solution of 1.0 x 107 colony forming units (CFU)/mL. For both methods, lenses were incubated in the solution for 16 hours. After removal, the viable cells were diluted in serial dilutions. Aliquots of each dilution were plated on a trypticase soy agar plate and incubated for 24 hours at 37°C. After 24 hours, the CFU per lens were calculated manually under magnification.

Results: Using the in-vitro drip method, adhesion of Staphyloccocus aureus onto senofilcon A was successfully demonstrated. Preliminary analysis showed no significant difference (p = 0.34) between the drip and soak method when compared at high CFU/mL.

Conclusion: The novel drip method is a promising alternative to the conventional soak method, as this model is closer to the contamination that would occur in a human eye. The drip method may be an acceptable method of testing once the method can be further developed and tested in future studies, using a variety of lenses and bacteria.