Peer-reviewed Articles

Please use the year list below to look at past peer-reviewed articles.

2022

Chamberlain,P., Bradley,A., Arumugam,B., Hammond,D., McNally,J., Logan N., Jones,D., Ngo,C., Peixoto-de-Matos S., Hunt,C., Young G. Long-term Effect of Dual-focus Contact Lenses on Myopia Progression in Children: A 6-year Multicenter Clinical Trial Optometry & Vision Science 2022;99(3):204-212 [ Show Abstract ]

Significance: Treatment of myopic children with a dual-focus soft contact lens (DFCL; MiSight 1 day) produced sustained slowing of myopia progression over a six-year period. Significant slowing was also observed in children switched from control to treatment lenses (3 years in each lens).

Purpose: Evaluate the effectiveness of DFCLs in sustaining slowed progression of juvenile-onset myopia over a 6-year treatment period. Assess myopia progression in children who were switched to DFCL at the end of year 3.

Methods: Part 1 was a 3-year clinical trial comparing DFCLs with control CLs (Proclear 1 day) at four investigational sites. In Part 2, subjects completing Part 1 were invited to continue for 3 additional years during which all children were treated with MiSight 1 day DFCLs (52 and 56 from the initially treated (T6) and control (T3) groups, respectively). 85 subjects (45 (T3) and 40 (T6)) completed Part 2. Cyclopleged spherical equivalent refractive errors (SERE) and axial lengths (AL) were monitored and linear mixed model was used to compare their adjusted change annually.

Results: Average age at Part 2 baseline was 13.2 ± 1.3 and 13.0 ± 1.5 for the T6 & T3 groups respectively. Slowed myopia progression in the T6 group observed during Part 1 was sustained throughout Part 2 (Mean ± SEM: Change from baseline SERE(D) = -0.52 ± 0.076 vs -0.51 ± 0.076; change in AL(mm) = 0.28 ± 0.033 vs 0.23 ± 0.033, both P > .05). Comparing progression rates in Part 2 for the T6 and T3 groups respectively indicate that prior treatment does not influence efficacy (SERE -0.51 ± 0.076 vs -0.34 ± 0.077; AL 0.23 ± 0.03 vs 0.18 ± 0.03, both P > .05). Within-eye comparisons of AL growth revealed a 71% slowing for the T3 group (3-years older than Part 1), and further revealed a small subset of eyes (10%) that did not respond to treatment.

Conclusions: DFCLs continue to slow the progression of myopia in children over a six-year period revealing an accumulation of treatment effect. Eye growth of the initial control cohort with DFCL was slowed by 71% over the subsequent 3-year treatment period.

Desai,D. T., Maulvi,F. A., Desai,A. R., Shukla,M. R., Desai,B. V., Khadela,A. D., Shetty,K. H., Shah,D. O., Willcox,M. D. P. In vitro and in vivo evaluation of cyclosporine-graphene oxide laden hydrogel contact lenses International Journal of Pharmaceutics 2022;613121414 [ Show Abstract ]

Drug-eluting contact lens can substitute the multiple eye drop therapy. However, loading hydrophobic drug like cyclosporine in the contact lens is very challenging, due to low drug uptake (via soaking method); and alteration in the swelling and optical properties which restricts its clinical application. To address the above issues, graphene oxide (GO, large surface area with oxygen containing functional groups) was incorporated in the contact lenses during fabrication. These GO-laden contact lenses (SM-GO-Cys) as well as blank contact lenses (SM-Cys) were soaked in the solution of cyclosporine. Alternatively, cyclosporine-laden contact lenses (DL-Cys-20) and cyclosporine-GO-laden contact lenses (DL-Cys-20-GO) were fabricated by adding drug and drug-GO (at various level of GO) during fabrication, respectively. Contact angle and swelling data showed increase in water holding capacity of GO laden contact lenses. Optical property was significantly improved due to molecular dispersion of drug on the surface of GO sheets. The drug uptake and in vitro release profile was improved with GO-laden contact lenses by soaking method (SM-GO-Cys-400n) due to hydrophobic interactions between GO and drug. Adding cyclosporine-GO (DL-Cys-20-GO-800n) during fabrication significantly improved drug release kinetics with higher drug leaching (during extraction and sterilization) due to increased swelling, improved dissolution and molecular dispersion of drug on GO sheets. Ocular irritation and histopathological studies demonstrated the safety of GO-contact lens. The in vivo drug release studies in the rabbit eye showed significant improvement in mean residence time (MRT) and area under the curve (AUC) using DL-Cys-20-GO-800n contact lens compared to eye drop solution with reduction in protein adherence value. The study demonstrated that the incorporation of GO into the contact lens can control the release of cyclosporine as well as improved the lens swelling and transmittance properties.

Efron,N., Jones,L. W., Morgan,P. B., Nichols,J. J. Bibliometric analysis of the literature relating to silicone hydrogel and daily disposable contact lenses Journal of Optometry 2022;15(1):44-52 [ Show Abstract ]

Purpose
Publication metrics are derived for the fields of silicone hydrogel (SH) and daily disposable (DD) contact lenses.

Methods
A search of the Scopus database for papers in the fields of SH and DD contact lenses found 979 SH and 291 DD papers. Subject-specific h-indices for SH lenses (hSH-index) and DD lenses (hDD-index) were derived, in relation to five categories – authors, institutions, countries and journals – to serve as measures of impact. A short list of the most impactful entities was generated for each of the above five categories in the SH and DD fields.

Results
A paper entitled “Soft contact lens polymers: An evolution” by Nicholson and Vogt was the most highly cited article (495 citations) in both SH and DD fields. The most impactful entities for the SH and DD fields were: authors – Lyndon Jones (hSH = 33) and Philip Morgan (hDD = 15); institutions – the University of Waterloo (hSH = 37) and the University of New South Wales (hDD = 15); countries – the United States (hSH = 45) and the United Kingdom (hDD = 24); and journals – Optometry and Vision Science (hSH = 33) and Contact Lens and Anterior Eye (hDD = 17). Overall, the SH field (hSH = 64) is far more impactful than the DD field (hDD = 34).

Conclusions
Impactful papers, authors, institutions, countries and journals in the SH and DD fields are identified. Optometry is revealed as the leading profession in relation to SH and DD publications.

Efron,N., Morgan,P. B., Nichols,J. J., Walsh,K., Willcox,M. D., Wolffsohn,J. S. Jones,L. W. All soft contact lenses are not created equal Contact Lens Anterior Eye 2022;45(2):Article 101515 [ Show Abstract ]

Abstract
Soft contact lenses that have been prescribed by eye care practitioners are sometimes substituted for alternative lenses by unqualified, unregulated and sometimes even fully regulated lens suppliers, in the mistaken belief that there is essentially no difference between different soft lens types. This review considers the implications of inappropriately substituting soft contact lens types in terms of (a) lens properties: surface treatment, internal wetting agents, material, total diameter, back optic zone radius, thickness, edge profile, back surface design, optical design, power, colour (tint) and ultraviolet protection; and (b) lens usage: wearing modality (daily versus overnight wear) and replacement frequency. Potential aspects of patient dissatisfaction and adverse events when prescribed soft lenses are substituted for lenses with different properties or intended usage are considered. Substitution of 15 of the 16 lens properties considered (i.e. except for back surface design) was found to be related to at least one – and as many as six – potential sources of patient dissatisfaction and adverse ocular events. Contact lens are medical devices which are prescribed and fitted; they should never be substituted for another lens type in the absence of a new prescription further to a full finalised fitting, for the simple reason that all soft contact lenses are not created equal. A substituted lens may have properties that results in undesirable consequences in respect of vision, ocular health, comfort and cosmetic appearance, and may be incompatible with the lifestyle of the patient.

Guthrie,S., Ng,A. Y., Woods,J., Vega,J., Orsborn,G., Jones,L. Exploring the factors which impact overall satisfaction with single vision contact lenses Contact Lens Anterior Eye 2022;Online ahead of print [ Show Abstract ]

Purpose
To explore the impact of subjective factors (lens handling, comfort and vision) on overall single vision contact lens satisfaction.

Methods
Correlation analysis of a prospective, randomised, double-masked, bilateral crossover study involving 55 adapted lens wearers fitted with somofilcon A (SiHy) (clariti® 1 day, CooperVision) and etafilcon A (Hy) (1 DAY ACUVUE® MOIST, Johnson & Johnson Vision) was conducted. Subjective ratings of lens handling, comfort and vision collected after 1 week of lens wear for each lens type were correlated with overall satisfaction. Data were analysed by combining data for both lens types and also for each lens separately.

Results
For the combined analysis, significant correlations (p < 0.01) were found between subjective ratings of overall satisfaction and ratings of handing for application (r = 0.64), handling for removal (r = 0.50), comfort upon application (r = 0.59), comfort at end of day (r = 0.61), overall satisfaction with comfort (r = 0.88) and overall satisfaction with vision (r = 0.64).

Correlation analysis of the per lens data showed that lens specific correlations of overall satisfaction with handling for lens application varied greatly with lens material (SiHy: r = 0.26, p = 0.05 vs Hy: r = 0.72, p < 0.01). Correlation strength of comfort upon application/at end of day with overall satisfaction also varied with lens material (Application: SiHy: r = 0.40 vs Hy: r = 0.61; End of day: SiHy: r = 0.76 vs Hy: r = 0.58; all p ≤ 0.01).

Conclusion
Overall satisfaction was significantly correlated with the specific subjective evaluations of handling, vision and comfort. Correlations of overall satisfaction and ease of handling for each lens type suggest that, for habitual contact lens wearers, dissatisfaction with handling at the time of lens application can play a major role in overall dissatisfaction with a lens. Handling for application had a similar correlation (r) value as vision, suggesting that handling for application should not be underestimated when considering overall patient satisfaction.

Kao,E. C. Y., Seo,J., McCanna,D. J., Subbaraman,L. N., Jones,L. In vitro assessment of the biocompatibility of chemically treated silicone materials with human lens epithelial cells Nature - Scientific Reports 2022;12(1):Article 4649 [ Show Abstract ]

Cytotoxicity testing is a regulatory requirement for safety testing of new ocular implants. In vitro toxicity tests determine whether toxic chemicals are present on a material surface or leach out of the material matrix. A method of evaluating the cytotoxicity of ocular implants was developed using fluorescent viability dyes. To assess the assay’s sensitivity in detecting toxic substances on biomaterials, zinc diethydithiocarbamate (ZDEC) and benzalkonium chloride (BAK) were deposited on silicone surfaces at different concentrations. Human lens epithelial cells (HLEC) were added to the surface of these treated silicone surfaces and were assessed for viability. The viability of both the adherent and non-adherent cells was determined using confocal microscopy with, annexin V, ethidium homodimer, and calcein. Cell metabolism was also evaluated using resazurin and the release of inflammatory cytokines was quantified using a multiplex Mesoscale Discovery platform. Confocal microscopy was shown to be a sensitive assay for evaluating material toxicity, as significant toxicity (p < 0.05) from ZDEC and BAK-treated surfaces compared to the untreated silicone control was detected. Patterns of cytokine release from cells varied depending on the toxin evaluated and the toxin concentration and did not directly correlate with the reduction in cell metabolic activity measured by alamarBlue.

Kapadia,W., Qin,N., Zhao,P., Phan,C.-M., Haines,L., Jones,L. Ren,C. L. Shear-Thinning and Temperature-Dependent Viscosity Relationships of Contemporary Ocular Lubricants Translational Vision Science & Technology 2022;11(3):Article 1 [ Show Abstract ]

Purpose: To evaluate the shear viscosity of contemporary, commercially available ocular lubricants at various shear rates and temperatures and to derive relevant mathematical
viscosity models that are impactful for prescribing and developing eye drops to treat dry eye disease.

Methods: The shear viscosity of 12 ocular lubricants was measured using a rheometer and a temperature-controlled bath at clinically relevant temperatures at which users may experience exposure to the drops (out of the refrigerator [4.3°C]; room temperature [24.6°C]; ocular surface temperature [34.5°C]). Three replicates for each sample at each temperature were obtained using a standard volume (0.5 mL) of each sample. The viscosity of each ocular lubricant was measured over the full range of shear rates allowed
by the rheometer.

Results: The shear viscosity of the same ocular lubricant varied significantly among the three temperatures. In general, a higher temperature resulted in smaller viscosities than a lower temperature (an average of −48% relative change from 4.3°C to 24.6°C and −21% from 24.6°C to 34.5°C). At a constant temperature, the viscosity of an ocular lubricant over the studied shear rates can be well approximated by a power-law model.

Conclusions: Rheological analysis revealed that the ocular lubricants exhibited shear-thinning behavior at the measured temperatures. Differences in the ocular lubricants’ formulations and measured temperatures resulted in different viscosities.

Translational Relevance: When prescribing eye drops, eye care professionals can select the optimal one for their patients by considering a variety of factors, including its
rheological property at physiologically relevant shear rates and temperatures, which can improve residence time on the ocular surface, while ensuring appropriate comfort and vision. However, care must be taken when using the derived mathematical models in this study because the in vivo shear behavior of the ocular lubricants has not been examined and might show deviations from those reported when placed on the ocular surface.

Khanal,S., Bai,Y., Ngo,W., Nichols,K. K., Wilson,L., Barnes,S., Nichols,J. J. Human meibum and tear film derived cholesteryl and wax esters in meibomian gland dysfunction and tear film structure: Cholesteryl and wax esters in meibomian gland dysfunction Ocular Surface 2022;23(January):12-23 [ Show Abstract ]

Purpose
This study evaluated the presence and roles of cholesteryl esters (CEs) and wax esters (WEs) from human tear film and meibum in meibomian gland dysfunction (MGD).

Methods
Out of 195 enrolled subjects, 164 and 179 subjects provided tear and meibum samples, respectively. Subjects were classified into normal, asymptomatic MGD, MGD, and mixed (MGD & aqueous deficient). The precorneal tear film (PCTF) thinning rate (evaporation) was measured using optical coherence tomography. Lipids extracted from tear and meibum samples were infused into a SCIEX 5600 TripleTOF mass spectrometer. CE and WE intensities quantified with Analyst 1.7 TF and LipidView 1.3 were compared across disease groups in MetaboAnalyst 5.0 and correlated with PCTF thinning rates.

Results
The numbers of unique CEs and WEs identified in the samples were 125 and 86, respectively. Unsupervised Principal Component (PC) analysis and supervised Partial Least Square Discriminant analysis exhibited little separation among groups for both CEs and WEs in tears and meibum. Spearman's correlation analyses showed no association between either the first or second PC scores with PCTF thinning rates.

Conclusion
The abundances of human PCTF and meibum-derived CEs and WEs were independent of MGD disease status and PCTF thinning (evaporation). CEs and WEs alterations do not contribute to alterations in tear film dynamics in MGD, such as has been demonstrated by the (O-acyl) ω-hydroxy fatty acids (OAHFAs).

Ng,A. Y., Woods,J., Jahn,T., Jones,L., Ritter,J. Effect of a novel omega-3 and omega-6 fatty acid supplement on dry eye disease: a 3-month randomized controlled trial Optometry & Vision Science 2022;99(1):67-75 [ Show Abstract ]

SIGNIFICANCE
Supplementing diet with a novel combination of omega-3 and omega-6 fatty acids significantly improved symptoms in extremely symptomatic participants with dry eye disease (DED).

PURPOSE
This study aimed to determine the effect of daily intake of a novel combination of essential fatty acids on signs and symptoms of DED.

METHODS
Participants with moderate to severe DED were enrolled in a prospective, randomized, double-masked parallel group study. Participants ingested either the treatment supplement containing omega-3 and omega-6 fatty acids (1200 mg eicosapentaenoic acid, 300 mg docosahexaenoic acid, 150 mg γ-linoleic acid) or the placebo (coconut and olive oil) daily for 3 months. To determine compliance, Omega-3 Index blood tests were conducted. At baseline and at 1 and 3 months, the following assessments were conducted: Ocular Surface Disease Index (OSDI) questionnaire and Symptom Assessment Questionnaire in Dry Eye, noninvasive tear breakup time, tear meniscus height, tear osmolarity, ocular redness, surface staining, Schirmer test, and meibography.

RESULTS
Fifty participants (mean ± standard deviation baseline OSDI score, 52.2 ± 16.5) completed the study: 24 randomized to treatment and 26 randomized to placebo. Although there was an improvement in OSDI score at 3 months for both groups (treatment: −13.4 points, P = .003; placebo: −7.8 points, P = .02), participants with baseline OSDI scores >52 demonstrated an even larger significant improvement in symptoms with the treatment at 3 months compared with baseline (n = 13, −20.8 points, P = .002). There were no significant changes in any of the ocular assessments at 1 or 3 months (all P > .05). After 3 months, Omega-3 Index increased by 34% in the treatment group (baseline, 5.3 ± 0.8; 3 months, 8.0 ± 2.1; P < .001) and did not change in the placebo group (baseline, 4.8 ± 0.8; 3 months, 4.8 ± 0.6; P = .95).

CONCLUSIONS
Supplementation with eicosapentaenoic acid, docosahexaenoic acid, and γ-linoleic acid resulted in a significant and clinically meaningful improvement of dry eye symptoms in extremely symptomatic participants with DED (OSDI ≥52).

Nichols,J. J., Morgan,P. M., Efron,N, Jones,L. W. Global optometrist research ranking derived from a science-wide author database of standardised citation indicators Clinical and Experimental Optometry 2022;105(1):20-25 [ Show Abstract ]

Clinical relevance
Publications in refereed scientific journals provide a rigorous research base that underpins clinical optometric practice. Leading optometrists who generate this literature can be identified and ranked using standardised citation indicators.

Background
This work seeks to identify and rank all optometrists included in a Science-Wide author database of standardised citation indicators (S-W) and to compare this ranking with the Global Optometrist Top 200 Research Ranking (T200).

Methods
A search was conducted for the names of all optometrists in the T200 who were included in the S-W, which is a world-wide listing of the top 2% of scientists in each of 174 subfield disciplines, ranked according to a composite citation indicator (cns) that excludes self-citations and corrects for multiple authorships and author order.

Results
The names of 66 optometrists are found in the S-W. Of these, 58 are designated as working in the primary sub-field ‘Ophthalmology & Optometry’; this listing, in rank-order of cns, is referred to as the ‘S-W-derived Optometrist Research Ranking’ (S-WORR). Australian optometrist Nathan Efron is ranked #1 in the S-WORR. The number (%) of optometrists in the S-WORR from each country is: the United States – 26 (45%), Australia – 12 (21%), the United Kingdom – 11 (19%), Canada – 5 (9%), Spain – 2 (3%), Hong Kong – 1 (2%) and South Africa – 1 (2%). The universities housing the equal highest number of optometrists in the S-WORR (five each) are the University of California, Berkeley, USA; the University of New South Wales, Australia; and Queensland University of Technology, Australia. There is a moderately strong correlation between T200 and S-WORR rankings (ρ = 0.6017, N = 58, p < 0.0001).

Conclusions
The S-WORR represents an elite cohort of optometrists who ought to be celebrated for their outstanding, leading and impactful contributions to optometric research.

Nogueira,C. L., 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.

Osae,E. A., Jones,L., Nichols,J. J. The impact of contact lenses on meibomian gland morphology Ocular Surface 2022;24(April):148-155 [ Show Abstract ]

Despite years of experience with contact lenses, controversy remains as to whether contact lenses adversely impact the meibomian glands (MG). This review summarizes the present body of evidence, showing that contact lens wear is associated with alterations in MG morphology (up to 80% higher gland atrophy compared to non-wearers) and qualitative changes in MG secretion. Key factors such as duration of contact lens wear, contact lens type (e.g., soft vs. rigid), edge design, and material modulus of elasticity are discussed in relation to the extent of MG morphological changes, the quality of MG secretion and other ocular surface parameters. Longitudinal studies of sufficient statistical power are needed to better understand how contact lens wear affects the MG, risk factors, and the clinical sequelae of these changes.

Pereira-da-Mota,A. F., Phan,C-M., Concheiro,A., Jones,L., Alvarez-Lorenzo,C. Testing drug release from medicated contact lenses: The missing link to predict in vivo performance Journal of Controlled Release 2022;343(March):672-702 [ Show Abstract ]

Contact lenses (CLs) offer a wide variety of advantages as ocular drug-releasing platforms, but the feasibility of medicated CL development is constrained by numerous scientific, technological, and regulatory challenges. One main difficulty is the setting of release rate specifications for each drug, since at present there are no standardized in vitro release models that can appropriately predict the performance of drug-eluting CLs once placed onto the eye. CL-adapted release tests may provide knowledge on how the drug release pattern should perform in vivo to trigger and maintain the therapeutic effects for both anterior and posterior ocular tissues. Moreover, in vitro release tests are valuable tools for quality assessment during production and to investigate the effect of a change in composition or process variables. This review aims to shed light on biorelevant ways of evaluating in vitro drug release from CLs and the feasibility of establishing in vitro-in vivo correlations (IVIVC) to predict in vivo performance. First, general guidelines and Pharmacopeia release tests for topical ophthalmic formulations as well as in vitro release tests implemented for drug-CLs in the last two decades are analyzed. Then, development of an appropriate method to investigate IVIVC is attempted from the few papers simultaneously reporting in vitro release profiles and either in vivo release or therapeutic response. Finally, key points to be considered for in vitro testing drug release from a medicated CL are suggested to pave the way to the clinical arena.

von Ahrenschildt,A., Hanneberg,L., Robich,M., Jones-Jordan,L., Marx,S., Sickenberger,W., Powell,D., Kwan,J. T., Wong,S., Srinivasan,S., Jones,L., Pucker,A. D. Morphological characteristics of Meibomian Glands and their Influence on Dry Eye disease in contact lens wearers Ocular Surface 2022;24(April):93-99 [ Show Abstract ]

Purpose:
Meibomian glands (MG) are now easily imaged via clinical meibography machines. The purpose of this work was to explore the utility of the known MG morphology metrics for predicting dry eye disease (DED) in contact lens (CL) wearers.

Methods:
Successful and previous CL wearers were recruited. DED was diagnosed if the participant's worst eye had a reduced tear meniscus height (TMH) of <0.2 mm or non-invasive tear break-up time (NITBUT) of [removed]5.0. Meibography was performed and images were subjectively graded by two examiners for the following MG characteristics: distorted, tortuous, hooked, abnormal gap, overlapping, fluffy areas, tadpoling, thinned, thickened, ghost, no extension to lid margin, shortened and dropout (atrophy). DED diagnostic ability of each metric was determined with receiver operating characteristic (ROC) analysis.

Results:
A total of 112 participants were recruited, with 18.8% having DED and 60.7% being female. The only MG morphology metrics that were marginally predictive of DED were thickened upper eyelid MGs (p = 0.046), thickened mean upper plus lower eyelid MGs (p = 0.007), and atrophy of upper eyelid MGs (p = 0.043); however, none of these metrics reached a meaningful area under the curve in ROC analysis (all <0.70).

Conclusion:
While abnormal MG morphology is likely suggestive of DED in CL wearers, none of the MG morphology metrics evaluated alone in this study had clinically meaningful predictive value for detecting DED in this group of current and previous CL wearers.

Wolffsohn,J. S., Dhallu,S., Aujla,M., Laughton,D., Tempany,K., Powell,D., Gifford,K., Gifford,P., Wan,K., Cho,P, Stahl,U., Woods,J. International multi-centre study of potential benefits of ultraviolet radiation protection using contact lenses Contact Lens Anterior Eye 2022;Online ahead of print [ Show Abstract ]

Purpose
To examine the effects of long-term ultraviolet radiation (UVR) blocking wearing contact lenses on ocular surface health, eye focus and macular pigment.

Method
210 pre-presbyopic patients were recruited from Birmingham UK, Brisbane Australia, Hong Kong China, Houston USA and Waterloo Canada (n = 42 at each site). All patients had worn contact lenses for ≥ 5 years, half (test group) of a material incorporating a UVR-blocking filter. Ocular health was assessed using slit-lamp biomicroscopy and UV autofluorescence. Accommodation was measured subjectively with a push-up test and overcoming lens-induced defocus. Objective stimulus response and dynamic measures of the accommodative response were quantified with an open-field aberrometer. Macular pigment optical density (MPOD) was assessed using heterochromatic flicker photometry (MPS II).

Results
The two groups of participants were matched for age, sex, race, body-mass-index, diet, lifestyle, UVR exposure, refractive error and visual acuity. Limbal (p = 0.035), but not bulbar conjunctival redness (p = 0.903) was lower in eyes that had worn UVR-blocking contact lenses compared to controls. The subjective (8.0 ± 3.7D vs 7.3 ± 3.3D; p = 0.125) and objective (F = 1.255, p = 0.285) accommodative response was higher in the test group, but the differences did not reach significance. However, the accommodative latency was shorter in eyes that had worn UVR-blocking contact lenses (p = 0.003). There was no significant different in MPOD with UVR filtration (p = 0.869).

Conclusions
Blocking the transmission of UVR is beneficial in maintaining the eye’s ability to focus, suggesting that presbyopia maybe delayed in long-term UVR-blocking contact lenses wearers. These lenses also provide protection to the critical limbal region.

Yee,A., Phan,C-M., Jones,L. Uptake and release of polyhexamethylene biguanide (PHMB) from hydrogel and silicone hydrogel contact lenses using a radiolabel methodology Contact Lens Anterior Eye 2022;Online ahead of print [ Show Abstract ]

Purpose
The purpose of this study was to evaluate the uptake and release of radiolabelled polyhexamethylene biguanide (PHMB) on reusable daily wear contact lenses (CLs) over 7 days.

Methods
Three silicone hydrogel (SH) contact lens materials (lotrafilcon B, balafilcon A, senofilcon A) and two conventional hydrogel (CH) materials (etafilcon A, omafilcon A) were examined. In experiment 1 (1-day study), CLs were soaked in 2 mL of phosphate buffered solution (PBS) containing radiolabelled 14C PHMB (1 µg/mL) for 8 h. The release kinetics of 14C PHMB from the CLs was measured at t = 0.25, 0.5, 1, 2, 4, 8, and 24 h in fresh 2 mL PBS. In experiment 2 (7-day study), the CLs were soaked in the 14C PHMB (1 µg/mL) solution for 8 h followed by a 16-hour release in 2 mL PBS. The lens cycle was repeated daily for 7 days. After both experiments, the residual amount of PHMB remaining within the lenses was extracted to determine the total uptake of PHMB.

Results
In experiment 1, the total uptake of PHMB for etafilcon A was significantly greater than senofilcon A (p = 0.01). There were no significant differences in total uptake of PHMB between other lens materials (p > 0.05). Etafilcon A released more PHMB compared to all other lens types over a 24-hr period (p < 0.001). In experiment 2, all CL materials continued to sorb more PHMB over time (p < 0.001). By day 7, the amount of PHMB sorbed by etafilcon A was significantly greater than senofilcon A (p = 0.02). After day 2, the CH materials released significantly more PHMB than the SH materials (p < 0.01).

Conclusion
The CL materials continued to sorb PHMB with no signs of saturation after 7 days. All lens materials released a consistent amount of PHMB each day. Radioactive labelling provides a sensitive method of assessing the uptake and release of PHMB from CL materials.