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Peer-reviewed articles

2020

Wolffsohn,J. S., Calossi,A., Cho,P., Gifford,K., Jones,L., Jones,D., Guthrie,S., Li,M., Lipener,C., Logan,N. S., Malet,F., Peixoto-de-Matos,S. C., González-Méijome,J. M., Nichols,J. J., Orr,J. B., Santodomingo-Rubido,J., Schaefer,T., Thite,N., van der Worp,E., Tarutta,E., Iomdina,E., Ali,B. M., Villa-Collar,C., Abesamis-Dichoso,C., Chen,C., Pult,H., Blaser,P., Parra Sandra Johanna,G., Iqbal,F., Ramos,R., Carrillo Orihuela,G., Boychev,N. Global trends in myopia management attitudes and strategies in clinical practice – 2019 Update Cont Lens Anterior Eye 2020;43(1):9-17 [ Show Abstract ]

Purpose: A survey in 2015 identified a high level of eye care practitioner concern about myopia with a reported moderately high level of activity, but the vast majority still prescribed single vision interventions to young myopes. This research aimed to update these findings 4 years later. Methods: A self-administrated, internet-based questionnaire was distributed in eight languages, through professional bodies to eye care practitioners globally. The questions examined: awareness of increasing myopia prevalence, perceived efficacy of available strategies and adoption levels of such strategies, and reasons for not adopting specific strategies. Results: Of the 1336 respondents, concern was highest (9.0 ± 1.6; p < 0.001) in Asia and lowest (7.6 ± 2.2; p < 0.001) in Australasia. Practitioners from Asia also considered their clinical practice of myopia control to be the most active (7.7 ± 2.3; p < 0.001), the North American practitioners being the least active (6.3 ± 2.9; p < 0.001). Orthokeratology was perceived to be the most effective method of myopia control, followed by pharmaceutical approaches and approved myopia control soft contact lenses (p < 0.001). Although significant intra-regional differences existed, overall, most practitioners did not consider single-vision distance under-correction to be an effective strategy for attenuating myopia progression (79.6 %), but prescribed single vision spectacles or contact lenses as the primary mode of correction for myopic patients (63.6 ± 21.8 %). The main justifications for their reluctance to prescribe alternatives to single vision refractive corrections were increased cost (20.6 %) and inadequate information (17.6 %). Conclusions: While practitioner concern about myopia and the reported level of activity have increased over the last 4 years, the vast majority of eye care clinicians still prescribe single vision interventions to young myopes. With recent global consensus evidence-based guidelines having been published, it is hoped that this will inform the practice of myopia management in future.

2015

Guthrie,S. E., Jones,L., Blackie,C. A., Korb,D. R. A Comparative Study Between an Oil-in-Water Emulsion and Nonlipid Eye Drops Used for Rewetting Contact Lenses Eye and Contact Lens 2015;41(6):373-377 [ Show Abstract ]

OBJECTIVES: The purpose of this study was to determine the clinical impact of using SYSTANE BALANCE Lubricant Eye Drops (Alcon, Fort Worth, TX), an oil-in-water emulsion, as a rewetting eye drop in symptomatic contact lens wearers.
METHODS: Subjects who had previously experienced contact lens discomfort (CLD), with a mean lens wearing history of 18.6±12.8 years, were randomly assigned to use a Test (SYSTANE BALANCE Lubricant Eye Drops; n=76) or control (habitual nonlipid contact lens rewetting eye drop; n=30) drop over their contact lenses within 5 min of lens insertion and then subsequently at 2 hr intervals up to a maximum of 4 drops per eye daily for a 1-month period. Assessments of subjective comfort, comfortable wearing time, lid wiper epitheliopathy (LWE), and corneal staining were conducted at baseline and after 1 month, after 6 hr of lens wear.
RESULTS: Comfort, wearing time, LWE, and corneal staining all showed statistically significant improvements in the test group using SYSTANE BALANCE Lubricant Eye Drops at the 1-month visit compared with baseline data (all P<0.01) and compared with the control group at the 1-month visit (P<0.01, P=0.01, P<0.01, and P=0.03, respectively).
CONCLUSIONS: The use of SYSTANE BALANCE Lubricant Eye Drops as a rewetting drop in a group of wearers who experienced symptoms of CLD improved subjective comfort scores, increased comfortable wearing time, and reduced signs of LWE and corneal staining, when compared with the use of non–lipid-containing contact lens rewetting eye drops.

2013

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.

Scientific Presentations

2019

Guthrie S, Moezzi A, Varikooty J, Woods J, Jones L. A bilateral dispensing evaluation of two different toric lens geometries
BCLA Conference, Manchester, UK, 2019 [ Show Abstract ][ PDF ]

Purpose: To evaluate the subjective acceptance of two different types of prism ballast toric lens geometries, when worn on a daily wear modality over 1 month.

Methods: The study was a prospective, double-masked, bilateral, randomized, cross-over, 1-month wear, dispensing study where 45 astigmats wore two different soft toric lenses: comfilcon A toric which utilises a uniform horizontal iso-thickness design and samfilcon A toric which utilises a thin-edge design. Assessments were completed at 1-month. Ratings (0-10 scale) were competed at 2-weeks and 1-month.

Results: At 1-month, investigator-rated lens fit acceptance was high for both lens designs (3.65 vs 3.58, p=0.29), as was logMAR visual acuity for high contrast, high illumination (-0.12 vs -0.12, p=0.63) and low illumination (-0.10 vs -0.09, p=0.71). Subjective ratings for ‘overall visual quality’ were significantly higher for comfilcon A at 1-month (8.1 vs 7.4, p=0.04), but not different at 2-weeks (8.2 vs 7,6, p=0.05). ‘Vision stability’ ratings were significantly higher for comfilcon A at 2-weeks (8.2 vs 7.3, p=0.01) and 1-month (8.0 vs 7.2, p=0.03). ‘Overall comfort’ was rated significantly better with comfilcon A at 2-weeks (8.1 vs 7.4, p=0.04) and 1-month (8.1 vs 7.4, p=0.03). ‘End of day comfort’ ratings were similar after 1-month but significantly better with comfilcon A at 2-weeks (7.2 vs 6.5, p=0.03). ‘Overall satisfaction’ was statistically higher for comfilcon A after 2-weeks (8.0 vs 7.0, p<0.01) and 1-month (7.8 versus 7.0, p=0.02). Comfortable wearing time was not different at 2-weeks (9.2 vs 8.8, p=0.12), but was significantly longer with comfilcon A at 1-month (8.9h vs 8.0h, p=0.03).

Conclusions: Although both comfilcon A and samfilcon A use a prism ballast stabilisation principle and both provide excellent acuity and lens fit results, comfilcon A provided better subjective results for vision, vision stability, comfort, comfortable wear time and overall satisfaction.

Guthrie S., Woods J., Moezzi A., Varikooty J., Jones L. Comparing in-office evaluations to subjective evaluations for two toric lenses American Academy of Optometry, Orlando, 2019 [ Show Abstract ][ PDF ]

Purpose: To evaluate the performance of two monthly replacement silicone hydrogel toric lenses, comfilcon A toric and samfilcon A toric, using in-office assessments and subjective evaluations after 1 month.

Methods: A prospective, double-masked, bilateral, cross-over, dispensing study was conducted, where 45 subjects wore each lens type in a reusable, daily wear modality for 1 month, in a randomised order. Both in-office and subjective evaluations (0 [worst]-10 [best] scale) were completed at 1-month.

Results: Comfilcon A and samfilcon A toric lenses both performed well and similarly in all aspects of investigator lens evaluation. At 1-month, there was no significant difference for ‘fit acceptance’ grades (3.65 vs 3.58, p=0.29), ‘overall lens stability’ (3.56 vs 3.42, p=0.09) or for measures of logMAR high contrast acuity under ‘high illumination’ (-0.12 vs -0.12, p=0.63) or ‘low illumination’ (-0.10 vs -0.09, p=0.71). However, subject evaluations did show some significant differences related to comfort and vision. At 1-month comfilcon A toric lenses were rated significantly better for ‘overall comfort’ (8.1 vs 7.4, p=0.03). The difference in the 1-month ratings for ‘end of day comfort’ was not statistically significant (7.1 vs 6.7, p=0.15), however the ‘comfortable wear time’ was significantly longer for comfilcon A toric (8.9h vs 8.0h, p=0.03). For vision, comfilcon A toric was rated significantly better for ‘overall vision quality’ (8.1 vs 7.4, p=0.04) and ‘vision stability’ (8.0 vs 7.2, p=0.03). Subjects were asked to rate their ‘overall satisfaction’ and comfilcon A toric was rated significantly higher (7.8 versus 7.0, p=0.02). Subjects were also asked if they had a lens preference. Of those with a preference, significantly more subjects preferred the comfilcon A toric lens in terms of comfort (32 vs 10, p<0.01), dryness (28 vs 10, p=0.01) and overall (31 vs 13, p=0.01).

Conclusions: Although both comfilcon A and samfilcon A toric lenses both provided similar, high-level results for lens fit, stability and acuity, comfilcon A toric was rated statistically significantly higher in the subjective evaluations, specifically for comfort, vision, vision stability, overall satisfaction and comfortable wear time. These results illustrate that the patient experience cannot always be predicted from in-office evaluations.

2018

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.

2016

Jones L, Guthrie S, Dumbleton K. Is there a relationship between care system and compliance? Asian Cornea and Contact lens Conference, Hong Kong, 2016 [ PDF ]

Stahl U, Keir N, Guthrie S, Jones L. Effect of monocular lens wear on ocular comfort TFOS conference, Montpelier, France, 2016

2015

Guthrie S, Dumbleton K, Jones L. Is there a relationship between care system and compliance? BCLA Clinical Conference and Exhibition, 2015 [ PDF ]

Guthrie S, Woods J, Dumbleton K, Fonn D, Jones L. Contact lens discomfort management strategies of ECPs Optom Vis Sci 2015;92: E-abstract 155050 [ PDF ]

2014

Dillehay S, Woods J, Situ P, Guthrie S, Paynor R, Griffin R, Tyson M, Jones L. Comparison of Three Power Levels of A Novel Soft Contact Lens Optical Design to Reduce Suspected Risk Factors for the Progression of Juvenile Onset Myopia Invest Ophthalmol Vis Sci 2014;55: E-abstract 3637

2011

Guthrie S, Woods J, Keir N, Dillehay S, Tyson M, Griffin R, Fonn D, Jones L, Irving E. Controlling lens induced myopia in chickens with peripheral lens design Optom Vis Sci 2011;88:E-Abstract 110421

Woods J, Guthrie S, Keir N, Choh V, Fonn D, Jones L, Irving E. Myopia development – what can the chicken tell us? Contact Lens & Anterior Eye 2011;34, Supplement 1:s13

Woods J, Guthrie S, Keir N, Dillehay S, Tyson M, Griffin R, Jones L, Irving E. The effect of a unique lens designed for myopia progression control (MPC) on the level of induced myopia in chicks Invest Ophthalmol Vis Sci 2011;51:E-Abstract 6651

2009

Brodland G, Jones L, Horst C, McDonald M, Guthrie S. A novel method for measuring contact lens tensile properties Optom Vis Sci 2009;86:E-abstract 095818

Dumbleton K, Richter D, Guthrie S, Woods C, Jones L, Fonn D. Patient and practitioner compliance with silicone hydrogel and daily disposable lens replacement CAO (Charlottetown, PEI), 2009

Dumbleton K, Woods C, Jones L, Guthrie S, Fonn D. Patient and practitioner compliance with silicone hydrogel and daily disposable lens replacement Contact Lens & Anterior Eye 2009;32, 5:213

Jones L, Brodland G, Horst C, McDonald M, Guthrie S. A novel method for measuring contact lens tensile properties Contact Lens & Anterior Eye 2009;32, 5:254

2008

Dalton K, Jones L, Guthrie S. pH, Osmolality and viscosity of artificial tears Optom Vis Sci 2008;85: E-abstract 85310

Dalton K, Jones L, Guthrie S. Physical properties of artificial tears Contact Lens & Anterior Eye 2008;31, 5:272

2006

Guthrie S, Simpson T, Varikooty J, Fonn D. Background subtraction and contrast enhancement for interferometric images of the human corneal tear film Invest Ophthalmol Vis Sci 2006;47:E-abstract 2399

Professional Publications

2019

Guthrie S. Summary: IMI Report on Experimental Models of Emmetropization and Myopia ContactLensUpdate.com 2019

Guthrie S. Report on Experimental Models of Emmetropization and Myopia - An article review ContactLensUpdate.com 2019

2016

Guthrie S, Dumbleton K, Jones L. Is there a Relationship Between Care System and Compliance? Contact Lens Spectrum 2016;31, April: 40-43

2014

Guthrie S, Dumbleton K, Jones L. Financial Implications of Patient Compliance Contact Lens Spectrum 2014;29, December: 42-45

2011

Guthrie S. Effect of dual-focus soft contact lens wear on axial myopia progression in children - An article review ContactLensUpdate.com 2011

2010

Richter D, Dumbleton K, Guthrie S, Woods C, Jones L, Fonn D. Patient and practitioner compliance with silicone hydrogel and daily disposable lens replacement in Canada Canadian Journal of Optometry 2010;72, 1: 10-19

Books

2020

Jones L, Stahl U, Guthrie S, Yang M, Yee A, Thom M. Contact Lens Compendium: Contact Lenses and Solutions Available in Canada. Vol 46 2020.

Jones L, Stahl U, Guthrie S, Yang M, Yee A, Thom M. Contact Lens Compendium: Contact Lenses & Solutions Available in America. Vol 1 2020.

2019

Jones L, Stahl U, Guthrie S, Luensmann D, Yang M, Thom M. Contact Lens Compendium: Contact Lenses and Solutions Available in Canada. Vol 45 2019.

2018

Jones L, Sorbara L, Stahl U, Yang M, Thom M, Guthrie S. Contact Lens Compendium: Contact Lenses and Solutions Available in Canada. Vol 44 2018.

2017

Jones L, Sorbara L, Stahl U, Thom M, Guthrie S. Contact Lens Compendium: Contact Lenses and Solutions Available in Canada. Vol 43 2017.

2016

Jones L, Sorbara L, Stahl U, Thom M, Guthrie S. Contact Lens Compendium: Contact Lenses and Solutions Available in Canada. Vol 42 2016.

2015

Jones L, Sorbara L, Stahl U, Thom M, Guthrie S. Contact Lens Compendium: Contact Lenses and Solutions Available in Canada. Vol 41 2015.

2014

Jones L, Sorbara L, Stahl U, Thom M, Guthrie S. Contact Lens Compendium: Contact Lenses and Solutions Available in Canada. Vol 40 2014.

2013

Jones L, Sorbara L, Stahl U, Guthrie S, Menzies K, Rossy J, Thom M. Contact Lens Compendium: Contact Lenses and Solutions Available in Canada. Vol 39 2013.