Peer-reviewed Articles

Please use the archived list on the right to look at past peer-reviewed articles.

2013

Craig,J. P., Willcox,M. D. P., Argüeso,P., Maissa,C., Stahl,U., Tomlinson,A., Wang,J., Yokoi,N., Stapleton,F. The TFOS International Workshop on Contact Lens Discomfort: Report of the contact lens interactions with the tear film subcommittee. Investigative Ophthalmology and Visual Science 2013;54,11:TFOS123-TFOS156.

Duench,S., Sorbara,L., Keir,N., Simpson,T., Jones,L. Impact of silicone hydrogel lenses and solutions on corneal epithelial permeability. Optometry and Vision Science 2013;90,6:546-556. [ Show Abstract ]

PURPOSE: The primary purpose of this pilot study was to compare epithelial barrier function (EBF) and staining in a small group of participants using a silicone hydrogel (SH) lens worn on a daily basis with two different care regimens. Secondarily, the aim was to see if there was any correlation between corneal staining and EBF. METHODS: The corneal EBF of 10 non-lens wearers (control) and 15 age-matched asymptomatic SH contact lens wearers (test) were assessed using fluorophotometry. Biomicroscopy was performed to assess corneal staining after the EBF was measured. The lens wearers wore PureVision (FDA group V) SH lenses for two consecutive 1-month periods while using either Alcon Opti-Free Express or Renu Fresh using a randomized, investigator-masked, crossover design. Control subjects were assessed on one occasion, and lens wearers were examined before fitting with lenses and after 7, 14, and 28 days of lens wear, with each combination. RESULTS: Compared with the control group, both study groups had an increase in epithelial permeability at baseline (p = 0.04). There were no changes in EBF during the treatment period for either solution (p = 0.87). A significant difference in EBF was found between the test groups during the treatment period (p = 0.02), with greater permeability in the Renu Fresh-disinfected lenses. There was poor correlation between corneal staining and EBF (r = 0.35, p > 0.05) because of large individual variations. CONCLUSIONS: Daily wear of highly oxygen-permeable SH lenses increases corneal epithelial permeability to fluorescein probably because of increased mechanical effects. In addition, certain lens-solution interactions can add to this effect, as seen in this study. Despite having a low amount of central corneal staining in the Renu Fresh group, staining and EBF did not prove to be well correlated. The presence of central corneal staining is a confounding factor when measuring EBF. Copyright © 2013 American Academy of Optometry.

Dumbleton,K. A., Richter,D., Woods,C. A., Aakre,B. M., Plowright,A., Morgan,P. B., Jones,L. W. A multi-country assessment of compliance with daily disposable contact lens wear. Contact Lens and Anterior Eye 2013;36,6:304-312. [ Show Abstract ]

Purpose: To investigate compliance with daily disposable contact lens (DDCL) wear and investigate re-use of lenses according to country and DDCL material worn. Methods: Optometrists invited eligible DDCL patients from their practices to participate in a survey on DDCL wear in Australia, Norway, the United Kingdom (UK) and the United States (US). Eligible participants completed an online or paper version of the survey. Results: 805 participants completed the survey (96% online): Australia 13%, Norway 32%, UK 17%, US 38%. The median age was 38 years; 66% were female. Silicone hydrogel (SiHy) DDCLs were worn by 14%. Overall, 9% were non-compliant with DDCL replacement; Australia 18%, US 12%, UK 7% and Norway 4%. There were no differences with respect to sex, years of contact lens wear experience or DDCL material (SiHy versus hydrogels). The primary reason for re-use was "to save money" (60%). Re-use of DDCLs resulted in inferior comfort at insertion and prior to lens removal (p= 0.001). 75% reported occasional napping and 28% reported sleeping overnight for at least one night in the preceding month, while wearing their DDCLs. Conclusion: Non-compliance with replacement of DDCLs occurred in all countries investigated; the rate was highest in Australia and lowest in Norway. Re-use of DDCLs was associated with reduced comfort. DDCL wearers often reported wearing lenses overnight. It is important for optometrists to counsel their patients on the importance of appropriate lens wear and replacement for DDCLs. © 2013 British Contact Lens Association.

Dumbleton,K. A., Spafford,M. M., Sivak,A., Jones,L. W. Exploring compliance: A mixed-methods study of contact lens wearer perspectives. Optometry and Vision Science 2013;90,8:898-908. [ Show Abstract ]

PURPOSE: Using both quantitative and qualitative research methods, this article explores in detail the lens wear and care habits of adapted contact lens wearers and seeks a better understanding of what enables and constrains patient compliance with appropriate lens wear and lens care. METHODS: The study was conducted in two phases: a preliminary online questionnaire (quantitative phase), identifying types of noncompliance, and a series of sequentially conducted focus groups (qualitative phase), exploring constraints to, and enablers of, compliance. RESULTS: One hundred participants completed the online questionnaire; 12 of them also participated in one of four focus groups. The most frequently reported aspects of noncompliance revealed were failure to replace lenses when scheduled, inappropriate lens purchase and supply, sleeping while wearing lenses, use of tap water with lenses and failure to wash hands, failure to clean and replace cases regularly, and inappropriate use of care systems. Using an iterative process, a number of "themes" associated with noncompliance were identified in the focus group discussions. The most frequently occurring themes related to the consequences that may occur if patients were noncompliant with one or more aspects of their contact lens wear and the importance of receiving instructions regarding the most appropriate way to wear and care for their lenses. Most of the themes that emerged during the analysis were both constraints to, and enablers of, compliance. CONCLUSIONS: This study confirms the frequent types of noncompliance with contact lens wear and care while offering a greater understanding of what may constrain and enables contact lens wear and care compliance. Future qualitative studies may help eye care practitioners and the contact lens industry to develop strategies and tools to aid compliance and success in contact lens wear. © 2013 American Academy of Optometry.

Dumbleton,K., Caffery,B., Dogru,M., Hickson-Curran,S., Kern,J., Kojima,T., Morgan,P. B., Purslow,C., Robertson,D. M., Nelson,J. D. The TFOS International Workshop on Contact Lens Discomfort: Report of the subcommittee on epidemiology. Investigative Ophthalmology and Visual Science 2013;54,11:TFOS20-TFOS36.

Dumbleton,K., Richter,D., Bergenske,P., Jones,L. W. Compliance with lens replacement and the interval between eye examinations. Optometry and Vision Science 2013;90,4:351-358. [ Show Abstract ]

PURPOSE: Eye care practitioners (ECPs) acknowledge that their patients do not always follow recommendations for lens replacement, but many may not realize the possible implications for their offices. The study was conducted to investigate whether there is a relationship between contact lens compliance and the interval between full eye examinations (IEE). METHODS: The study was conducted in ECP offices in the United States. Eye care practitioners and patients independently completed linked questionnaires, evaluating their contact lens wear and care. Patients were required to be current wearers of daily disposable (DD) lenses or reusable silicone hydrogel lenses with a manufacturer-recommended replacement frequency (MRRF) of 2 weeks (2WR) or 1 month (1MR). RESULTS: A total of 2147 questionnaires from 141 offices were eligible. Fifty-four percent of patients were wearing 2WR, 37% 1MR, and 9% DD lenses. Wearers of 2WR lenses were significantly less compliant with replacement than wearers of both DD and 1MR lenses (34% vs. 74% and 67%, both p < 0.001); patients purchasing an annual supply were more compliant (55% vs. 45%, p < 0.001). The mean IEE was 16 months and was longer for wearers who were noncompliant with the MRRF (17.4 months vs. 14.5 months, p < 0.001). Other factors affecting IEE were household income (p = 0.030), insurance (p < 0.001), purchase source (p < 0.001), and sex (p = 0.007). CONCLUSIONS: Patients who were not compliant with the MRRF had longer IEEs and were less likely to purchase an annual supply of lenses. Patients who purchased lenses from their ECP, had a higher household income, had eye examination insurance, and were female had shorter IEEs. Patients failing to replace their lenses when scheduled were also found to be less compliant with lens care procedures. Eye care practitioners should reinforce the importance of all aspects of lens wear and care with their patients, with the overall aim of reducing possible complications and retaining successful contact lens wearers in their offices. Copyright © 2013 American Academy of Optometry.

Dumbleton,K., Woods,C. A., Jones,L. W., Fonn,D. The impact of contemporary contact lenses on contact lens discontinuation. Eye and Contact Lens 2013;39,1:93-99. [ Show Abstract ]

OBJECTIVES: Discontinuation or "dropout" from contact lens (CL) wear continues to afflict the CL industry. This study was conducted to determine whether the advent of new CL materials and designs has impacted the dropout rate and the reasons for discontinuation. METHODS: Current and lapsed CL wearers residing in Canada were recruited using Facebook to take part in an on line survey investigating CL wearing experiences during 2008 to 2010 and to establish the percentage of participants who temporarily and permanently discontinued CL wear during the period surveyed. RESULTS: Four thousand two hundred seven eligible surveys were received (64% female; median age 27 years). Forty percent had lapsed from lens wear for at least 4 months; however, 62% of the lapsed wearers (LWs) resumed wear. There were no differences between LWs and nonlapsed wearers (NLWs) with respect to gender; however, LWs were older, started lens wear when older, and had not worn lenses for as long as NLWs (all P<0.001). More NLWs than LWs wore silicone hydrogel CLs (49% vs. 38%, P<0.001) and more LWs than NLWs wore daily disposable lenses and hydrogel CLs (24% vs. 19% and 22% vs. 18%, respectively, P=0.001). Primary reasons for discontinuation were discomfort (24%), dryness (20%), red eyes (7%), and expense (7%). Compliance with lens replacement was no different between LWs and NLWs (48% vs. 45%). CONCLUSIONS: About 23% of those surveyed had discontinued CL wear permanently. The primary reasons for dropping out continue to be discomfort and dryness. Dropout rates were lower in silicone hydrogel wearers. © 2013 Lippincott Williams & Wilkins.

Efron,N., Brennan,N. A., Bright,F. V., Glasgow,B. J., Jones,L. W., Sullivan,D. A., Tomlinson,A., Zhang,J. Contact lens care and ocular surface homeostasis. Contact Lens and Anterior Eye 2013;36,SUPPL.:S9-S13. [ Show Abstract ]

The early focus of contact lens wear and ocular health was on oxygen delivery. However, as we learn more about how the eye works, and investigate how the contact lens interacts with the cornea, the role of the tear film has risen in prominence. A healthy tear film is critical for normal ocular homeostasis, and abnormalities of the tear film are the primary cause of dry eye. In order to improve patient eye health and comfort during lens wear, we need to further elucidate the relationship among contact lenses, contact lens solutions, the tear film, and the corneal epithelium, and find ways to maintain homeostasis of the ocular surface. In this section, we review the latest data and opinions on this complex relationship between contact lenses and lens care solutions. © 2013 British Contact Lens Association.

Efron,N., Jones,L., Bron,A. J., Knop,E., Arita,R., Barabino,S., McDermott,A. M., Villani,E., Willcox,M. D. P., Markoulli,M. The TFOS International Workshop on Contact Lens Discomfort: Report of the contact lens interactions with the ocular surface and adnexa subcommittee. Investigative Ophthalmology and Visual Science 2013;54,11:TFOS98-TFOS122.

Hall,B., Jones,L., Forrest,J. A. Measuring the kinetics and activity of adsorbed proteins: In vitro lysozyme deposited onto hydrogel contact lenses over short time periods. Journal of Biomedical Materials Research - Part A 2013;101 A,3:755-764. [ Show Abstract ]

A new process has been developed to determine the biological activity of an intact layer of lysozyme deposited onto a biomaterial surface. This process is applied to a number of common hydrogel contact lenses. The activity of the surface-adsorbed protein is measured using a standard micrococcal activity assay, with extra steps to distinguish between protein on the surface and protein in solution. This is in contrast to protein extraction work in which the activity of all adsorbed protein is measured. For ionic materials, which are known to deposit large amounts of protein, particularly positively charged proteins such as lysozyme, there is evidence for loosely bound protein re-entering the solution, thus making it impossible to truly separate out the surface-adsorbed protein. This optimized process provides the first quantification of the biological activity of an intact layer of surface-adsorbed protein at a hydrogel interface. © 2012 Wiley Periodicals, Inc.

Jones,L., Brennan,N. A., González-Méijome,J., Lally,J., Maldonado-Codina,C., Schmidt,T. A., Subbaraman,L., Young,G., Nichols,J. J. The TFOS International Workshop on Contact Lens Discomfort: Report of the contact lens materials, design, and care subcommittee. Investigative Ophthalmology and Visual Science 2013;54,11:TFOS37-TFOS70.

Jones,L., Powell,C. H. Uptake and release phenomena in contact lens care by silicone hydrogel lenses. Eye and Contact Lens 2013;39,1:29-36. [ Show Abstract ]

Contact lens solutions are highly complex mixtures of biocides (preservatives), surfactants, and other agents designed to disinfect, clean, and wet contact lenses. The commercialization of silicone hydrogel (SiHy) lenses has resulted in unique challenges to the manufacturers of contact lens solutions, because the properties of these materials differ markedly from those seen previously with poly-hydroxyethyl methacrylate-based hydrogels. Historically, hydrogel lens uptake and release of low-molecular weight preservatives such as chlorhexidine and thimerosal were known to result in allergic reactions, resulting in corneal irritation, stinging, conjunctival hyperemia, development of corneal infiltrates, palpebral lid changes, and corneal staining. However, little is known about the interaction of modern care systems with modern soft lens materials. Factors to be considered when evaluating the uptake and release of care components include the water content, charge, relative hydrophobicity, surface treatment, and porosity of the lens material, in conjunction with the concentration, charge/molecule, ionicity in the product matrix, molecular weight, and hydrophobicity of the care component in question. These factors control the sorption of the solution components by lenses, resulting in a variety of differences in the amount of the component taken up into the lens material and the amount and rate of subsequent release onto the ocular surface. Because both natural (ocular) and environmental biota become part of the solution-lens system during regimen use of any lens care product, these extraneously introduced substances should also be considered regarding their potential for uptake and either subsequent release onto the ocular surface or functioning as a scaffold for the adhesion of microbes. This article will review current knowledge concerning these interactions and investigate what clinically observable complications may arise from these interactions. It also reviews whether current methods to determine these interactions could be improved on. © 2013 Lippincott Williams & Wilkins.

Keech,A., Senchyna,M., Jones,L. Impact of time between collection and collection method on human tear fluid osmolarity. Current eye research 2013;38,4:428-436. [ Show Abstract ]

Aim: To generate data on the variability of tear osmolarity in a control (normal, non-dry eye) and symptomatic dry eye population (Ocular Surface Disease Index: OSDI ≥20). A secondary outcome is the determination of the effect that tear collection technique has on the osmolarity of the sample. Materials and methods: This was a two-phase study that recruited 20 subjects (n = 10 normal, n = 10 dry eye) to evaluate the influence of time between measurements (Phase I) and 30 subjects (n = 15 normal, n = 15 dry eye) to evaluate the influence of collection technique (Phase II). As part of Phase I, serial tear osmolarity measurements were performed on each eye; four separated by 15min followed by four separated by lmin, at each of three visits. Phase II compared the consecutive measurement of four in vivo tear samples to four in vitro measurements on tears collected and dispensed from a glass capillary tube. Results: During Phase I, the dry eye group had a significantly higher maximum osmolarity (334.2 ± 25.6 mOsm/L) compared to the normal group (304.0 ± 8.4mOsm/L, p = 0.002). No significant differences were observed whether collections were performed at 15 or 1 min intervals. During Phase II, the in vivo osmolarity was equivalent to in vitro measurements from glass capillary tube samples for both the dry eye group (323.0± 16.7mOsm/L versus 317.7±24.8, p = 0.496), and for the normal subjects (301.2±7. 2mOsm/L versus 301.9 ± 16.0 mOsm/L, p = 0.884). Conclusion: Symptomatic dry eye subjects exhibited a significantly higher tear osmolarity and variation over time than observed in normal subjects, reflecting the inherent tear film instability of dry eye disease. There was no change in the distribution of tear osmolarity measurements whether tears were collected in rapid succession or given time to equilibrate, and collection method had no impact on tear osmolarity. © Informa Healthcare USA Inc.

Keir,N., Jones,L. Wettability and silicone hydrogel lenses: A review. Eye and Contact Lens 2013;39,1:100-108. [ Show Abstract ]

One of the major breakthroughs in the development of silicone hydrogel contact lenses has related to the ability of manufacturers to overcome the surface hydrophobicity that occurred with silicone elastomer lenses. However, the wettability of silicone hydrogel lenses continues to be of interest as a potential link between in vivo lens performance and contact lens-related comfort. This article will review some of the knowledge we have gained in the area of contact lens wettability over the past decade and will discuss some of the challenges related to its measurement. © 2013 Lippincott Williams & Wilkins.

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.

Ngo,W., Srinivasan,S., Jones,L. Historical overview of imaging the meibomian glands. Journal of Optometry 2013;6,1:1-8. [ Show Abstract ]

Growing knowledge of the role of the meibomian glands in dry eye disease and contact lens discomfort has resulted in a surge of interest in visualizing these glands within the eyelids. This manuscript provides an overview of the many different visualization methods that have evolved over the past 30-40 years. Some of the visualization methods covered in this review include lid transillumination, video and non-contact meibography, and imaging methods employing confocal microscopy, optical coherence tomography and ultrasound. This review has also highlighted all the studies to date that have employed meibography as part of their methods. An overview of the available meibography dropout grading systems will also be provided. © 2012 Spanish General Council of Optometry.

Nichols,J. J., Jones,L., Daniel Nelson,J., Stapleton,F., Sullivan,D. A., Willcox,M. D. P. The TFOS International Workshop on Contact Lens Discomfort: Introduction. Investigative Ophthalmology and Visual Science 2013;54,11:TFOS1-TFOS6.

Nichols,J. J., Willcox,M. D. P., Bron,A. J., Belmonte,C., Ciolino,J. B., Craig,J. P., Dogru,M., Foulks,G. N., Jones,L., Nelson,J. D., Nichols,K. K., Purslow,C., Schaumberg,D. A., Stapleton,F., Sullivan,D. A. The TFOS International Workshop on Contact Lens Discomfort: Executive summary. Investigative Ophthalmology and Visual Science 2013;54,11:TFOS7-TFOS13.

Nichols,K. K., Redfern,R. L., Jacob,J. T., Nelson,J. D., Fonn,D., Forstot,S. L., Huang,J. -F, Holden,B. A., Nichols,J. J. The TFOS International Workshop on Contact Lens Discomfort: Report of the definition and classification subcommittee. Investigative Ophthalmology and Visual Science 2013;54,11:TFOS14-TFOS19.

Papas,E. B., Ciolino,J. B., Jacobs,D., Miller,W. S., Pult,H., Sahin,A., Srinivasan,S., Tauber,J., Wolffsohn,J. S., Nelson,J. D. The TFOS International Workshop on Contact Lens Discomfort: Report of the management and therapy subcommittee. Investigative Ophthalmology and Visual Science 2013;54,11:TFOS183-TFOS203.

Phan,C. -M, Subbaraman,L. N., Jones,L. In vitro uptake and release of natamycin from conventional and silicone hydrogel contact lens materials. Eye and Contact Lens 2013;39,2:162-168. [ Show Abstract ]

OBJECTIVES:: To investigate the uptake and release of the antifungal ocular drug, natamycin from commercially available conventional hydrogel (CH) and silicone hydrogel (SH) contact lens (CL) materials and to evaluate the effectiveness of this delivery method. METHODS:: Five commercial SH CLs (balafilcon A, comfilcon A, galyfilcon A, senofilcon A, and lotrafilcon B) and four CH CLs (etafilcon A, omafilcon A, polymacon, vifilcon A) were examined in this study. These lenses were incubated with natamycin solubilized in dimethyl sulfoxide, and the release of the drug from these lenses, in Unisol 4 pH 7.4 at 32±1 C, was determined using UV-visible spectrophotometry at 305 nm over 24 hours. RESULTS:: There was a significant uptake of natamycin between 0 hour and 24 hours (P0.05). There was a significant difference in release between all the SH materials (P0.05). There was a significant difference in release between all the SH materials (P0.05). There was a significant difference in release between all the SH materials (P0.05). Overall, the release of natamycin was higher in CH than SH lenses (P<0.001). CONCLUSIONS:: All CLs released clinically relevant concentrations of natamycin within 30 minutes, but this release reached a plateau after approximately 1 hour. Further CL material development will be necessary to produce a slow and sustained drug releasing device for the delivery of natamycin. © 2013 Lippincott Williams & Wilkins.

Robinson,B., Feng,Y., Woods,C. A., Fonn,D., Gold,D., Gordon,K. Prevalence of visual impairment and uncorrected refractive error-report from a canadian urban population-based study. Ophthalmic epidemiology 2013;20,3:123-130. [ Show Abstract ]

Purpose: The prevalence of visual impairment due to uncorrected refractive error has not been previously studied in Canada. A population-based study was conducted in Brantford, Ontario. Methods: The target population included all people 40 years of age and older. Study participants were selected using a randomized sampling strategy based on postal codes. Presenting distance and near visual acuities were measured with habitual spectacle correction, if any, in place. Best corrected visual acuities were determined for all participants who had a presenting distance visual acuity of less than 20/25. Results: Population weighted prevalence of distance visual impairment (visual acuity <20/40 in the better eye) was 2.7% (n=768, 95% confidence interval (CI) 1.8-4.0%) with 71.8% correctable by refraction. Population weighted prevalence of near visual impairment (visual acuity <20/40 with both eyes) was 2.2% (95% CI 1.4-3.6) with 69.1% correctable by refraction. Multivariable adjusted analysis showed that the odds of having distance visual impairment was independently associated with increased age (odds ratio, OR, 3.56, 95% CI 1.22-10.35; 65 years compared to those 39-64 years), and time since last eye examination (OR 4.93, 95% CI 1.19-20.32; 5 years compared to 2 years). The same factors appear to be associated with increased prevalence of near visual impairment but were not statistically significant. Conclusions: The majority of visual impairment found in Brantford was due to uncorrected refractive error. Factors that increased the prevalence of visual impairment were the same for distance and near visual acuity measurements. © 2013 Informa Healthcare USA, Inc. All rights reserved: reproduction in whole or part not permitted.

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.

Srinivasan,S., Menzies,K. L., Sorbara,L., Jones,L. W. Imaging meibomian glands on a patient with chalazia in the upper and lower lids: A case report. Contact Lens and Anterior Eye 2013;36,4:199-203. [ Show Abstract ]

Aim: To describe the meibomian gland (MG) appearance in a case of eyelid chalazia, using a novel meibography method. Methods: A 29-year-old female of South Asian origin presented with mild swelling in the lower lid of the left eye. The patient also presented with a history of a recurrent chalazion in the upper lid of the same eye, which later progressed to an active chalazion. A chalazion also developed in the upper lid of the right eye. Meibography was performed using a novel Keratograph (Keratograph 4, OCULUS, Wetzlar, Germany) to evaluate the structure of the MG in the area affected by the chalazia. Results: The area of the recurrent chalazion in the upper left lid showed partial and/or complete MG loss. The active chalazia in the lower left lid and the upper right lid showed inflammation and MG drop out at the affected site. The inflammation was found to be reduced during the follow-up visits, however disappearance of MG very specific to the region of the chalazion was observed. Conclusion: The Keratograph 4 was able to image the MG structures clearly, allowing the clinician to monitor the progression of chalazia and the MG loss in the affected areas. © 2013 British Contact Lens Association.

Varikooty,J., Keir,N., Richter,D., Jones,L. W., Woods,C., Fonn,D. Comfort response of three silicone hydrogel daily disposable contact lenses. Optometry and Vision Science 2013;90,9:945-953. [ Show Abstract ]

PURPOSE: To evaluate subjective ocular comfort across the day with three silicone hydrogel daily disposables (SHDDs) in a group of adapted lens wearers. METHODS: Masked subjects (asymptomatic or symptomatic of end-of-day (EOD) dryness with habitual lenses) wore three SHDDs: DAILIES TOTAL1 (DT1), Clariti 1day (C1D), or 1-DAY ACUVUE TRUEYE (AVTE), each for 3 days. On day 2, wearing time (WT) and comfort ratings after insertion, at 4, 8, and 12 hours, and at EOD were recorded. Because not all subjects wore lenses for 12 hours, comfort was analyzed across the day (up to 8 hours, 8 to 12 hours), and a new variable ("cumulative comfort" [CC]) was calculated for EOD. RESULTS: One hundred four subjects completed the study (51 asymptomatic, 53 symptomatic). The two groups had different WTs (mean WT, 14.0 and 12.7 hours, respectively; p < 0.001). Ocular comfort was rated higher in the asymptomatic group throughout the day (p < 0.001). One hundred four subjects wore all three SHDDs for at least 8 hours, whereas 74 (45 asymptomatic, 29 symptomatic) subjects wore them for 12 hours or longer. Comfort ratings were higher with DT1 (least square means [LSM] = 91.0) than with C1D (LSM = 86.5; p < 0.001) and AVTE (LSM = 87.7; p = 0.011) for the first 8 hours and lower with C1D compared with DT1 (p = 0.012) from 8 to 12 hours. Mean EOD (± SD) comfort with the C1D lens was 72 ± 21, lower than both DT1 (mean, 79 ± 17; p = 0.001) and AVTE (mean, 78 ± 21; p = 0.010). Mean CC was higher in the asymptomatic group (mean, 1261 ± 59) compared with that in the symptomatic group (mean, 1009 ± 58; p < 0.001) and higher for DT1 (mean, 1184 ± 258) than C1D (mean, 1094 ± 318; p = 0.002) and AVTE (mean, 1122 ± 297; p = 0.046). CONCLUSIONS: All three SHDDs had average WTs of 12 hours or longer for 1 day. Comfort during the first 12 hours was highest with DT1 (similar to AVTE between 8 and 12 hours) and lowest with C1D. End-of-day comfort was lowest with C1D, and CC was highest for DT1. Cumulative comfort may be a valuable new metric to assess ocular comfort during the day. © 2013 American Academy of Optometry.

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.

Weeks,A., Boone,A., Luensmann,D., Jones,L., Sheardown,H. The effects of hyaluronic acid incorporated as a wetting agent on lysozyme denaturation in model contact lens materials. Journal of Biomaterials Applications 2013;28,3:323-333. [ Show Abstract ]

Conventional and silicone hydrogels as models for contact lenses were prepared to determine the effect of the presence of hyaluronic acid on lysozyme sorption and denaturation. Hyaluronic acid was loaded into poly(2-hydroxyethyl methacrylate) and poly(2-hydroxyethyl methacrylate)/TRIS - methacryloxypropyltris (trimethylsiloxy silane) hydrogels, which served as models for conventional and silicone hydrogel contact lens materials. The hyaluronic acid was cross-linked using 1-ethyl-3-(3-dimethylaminopropyl)- carbodiimide in the presence of dendrimers. Active lysozyme was quantified using a Micrococcus lysodeikticus assay while total lysozyme was determined using 125-I radiolabeled protein. To examine the location of hyaluronic acid in the gels, 6-aminofluorescein labeled hyaluronic acid was incorporated into the gels using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide chemistry and the gels were examined using confocal laser scanning microscopy. Hyaluronic acid incorporation significantly reduced lysozyme sorption in poly(2-hydroxyethyl methacrylate) (p < 0.00001) and poly(2-hydroxyethyl methacrylate)/TRIS - methacryloxypropyltris (trimethylsiloxy silane) (p < 0.001) hydrogels, with the modified materials sorbing only 20% and 16% that of the control, respectively. More importantly, hyaluronic acid also decreased lysozyme denaturation in poly(2-hydroxyethyl methacrylate) (p < 0.005) and poly(2-hydroxyethyl methacrylate)/TRIS - methacryloxypropyltris (trimethylsiloxy silane) (p < 0.02) hydrogels. The confocal laser scanning microscopy results showed that the hyaluronic acid distribution was dependent on both the material type and the molecular weight of hyaluronic acid. This study demonstrates that hyaluronic acid incorporated as a wetting agent has the potential to reduce lysozyme sorption and denaturation in contact lens applications. The distribution of hyaluronic acid within hydrogels appears to affect denaturation, with more surface mobile, lower molecular weight hyaluronic acid being more effective in preventing denaturation. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Weeks,A., Subbaraman,L. N., Jones,L., Sheardown,H. Physical entrapment of hyaluronic acid during synthesis results in extended release from model hydrogel and silicone hydrogel contact lens materials. Eye and Contact Lens 2013;39,2:179-185. [ Show Abstract ]

OBJECTIVES:: This study was designed to assess the duration of hyaluronic acid (HA) release from model contact lens materials when HA was physically incorporated into the hydrogel during synthesis and to assess the effects of the HA release on lysozyme sorption. METHODS:: Model conventional and silicone hydrogel contact lens materials containing HA of various molecular weights as a releasable wetting agent were prepared. The HA was released into phosphate-buffered saline and MilliQ water, and the release was monitored using ultraviolet spectroscopy. Hyaluronic acid release was quantified by enzyme-linked immunosorbent assay. The effect of the releasable HA on lysozyme sorption to the materials was also analyzed using 125-I-labeled protein. RESULTS:: Hyaluronic acid loaded into the materials using this method could be released from conventional hydrogel materials for 21 days; the model silicone hydrogels showed release of more than 7 weeks. With one exception, the releasable HA decreased lysozyme sorption. CONCLUSIONS:: Hyaluronic acid physically incorporated into contact lens materials during synthesis may therefore be released for extended periods of time of up to 7 weeks. Hyaluronic acid release leads to decreased protein adsorption in general. This method has potential for modification of conventional and silicone hydrogel lenses with releasable HA as a wetting agent. © 2013 Lippincott Williams & Wilkins.

Woods,J., Guthrie,S. E., Keir,N., Dillehay,S., Tyson,M., Griffin,R., Choh,V., Fonn,D., Jones,L., Irving,E. Inhibition of defocus-induced myopia in chickens. Investigative Ophthalmology and Visual Science 2013;54,4:2662-2668. [ Show Abstract ]

PURPOSE. To determine the effect of wearing a lens with a unique peripheral optical design on the development and progression of defocus-induced myopia in newly hatched chickens.METHODS. Eighty-five newly hatched chickens underwent bilateral retinoscopy and A-scan ultrasound to determine their refractive error and axial length. They were randomly divided into Control and two Test groups, in which each chicken was fitted with a goggle-lens over the right eye, with the left eye remaining untreated. The Control group wore a lens of power - 10.00 diopters (D) of standard spherical optical design. The two Test lenses both had a central optical power -10.00 D, but used different peripheral myopia progression control (MPC) designs. For all groups, retinoscopy was repeated on days 3, 7, 10, and 14; ultrasound was repeated on day 14.RESULTS. On day 0 there was no statistical difference in refractive error (mean +6.92 D) or axial length (mean 8.06 mm) between Test and Control groups or treated and untreated eyes (all P > 0.05). At day 14, 37 (43.5%) of 85 chickens had not experienced goggle detachment and were included in the final analyses. In this cohort there was a significant refractive difference between the treated eyes of the Control group (n = 17) and those of Test 1 (n = 14) and Test 2 (n = 6) groups (both P < 0.01): Control -4.65 ± 2.11 D, Test 1 +4.57 ± 3.11 D, Test 2 +1.08 ± 1.24 D (mean ± SEM). There was also a significant axial length difference (both P < 0.01): Control 10.55 ± 0.36 mm, Test 1 9.99 ± 0.14 mm, Test 2 10.17 ± 0.18 mm.CONCLUSIONS. Use of these unique MPC lens designs over 14 days caused a significant reduction in the development of defocus-induced myopia in chickens; the degree of reduction appeared to be design specific. © 2013 The Association for Research in Vision and Ophthalmology, Inc.