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Peer-reviewed articles

2021

Schulze,M., Ng,A. Y., Yang,M., Panjwani,F., Srinivasan,S., Jones,L., Senchyna,M. Bulbar redness and dry eye disease: comparison of a validated subjective grading scale and an objective automated method Optometry & Vision Science 2021;98(2):113-120 [ Show Abstract ]

SIGNIFICANCE
In this study, assessments of conjunctival redness were performed to evaluate whether patients with or without dry eye disease (DED) could be discriminated based on this measure. Our findings suggest that subjectively grading redness by quadrant, as opposed to automated en face measurements, may be more suitable for this purpose.

PURPOSE
This study aimed to quantify bulbar redness using the validated bulbar redness (VBR) grading scale and an automated objective method (Oculus Keratograph 5M; K5M) in participants with DED and non-DED controls.

METHODS
Participants with DED (Ocular Surface Disease Index score ≥20 and Oxford scale corneal staining ≥2) and controls (Ocular Surface Disease Index score ≤10 and corneal staining ≤1) attended two study visits. In part 1A of visit 1, baseline bulbar redness was graded with the VBR scale in each conjunctival quadrant of both eyes, followed by automated measurements of temporal and nasal redness with the K5M. This was immediately followed by part 1B, during which a topical vasoconstrictor was instilled into both eyes. Redness assessments were repeated 5 and 30 minutes after instillation with both instruments. Participants returned 14 days later for visit 2, where the same assessments as for visit 1A were repeated.

RESULTS
Seventy-four participants (50 DED and 24 controls) completed the study. There were statistically significant differences in redness between the DED and control groups when assessed with the VBR scale (14/16 comparisons; all, P < .05), whereas no significant differences in K5M-derived redness between the DED and non-DED groups were found at any location or time point. Both subjective and objective instruments detected statistically significant reductions in redness 5 and 30 minutes after instillation of the vasoconstrictor (all, P < .01).

CONCLUSIONS
Although both subjective and objective instruments were sensitive to detecting changes in redness induced by vasoconstriction, statistically significant differences in redness between DED and control groups were only found using the VBR scale.

Yang,M., Ngo,W., Srinivasan,S., Heynen,M. L., Dantam,J., Subbaraman,L. N., Jones,L., Senchyna,M. Optimization of goblet cell density quantification methods Experimental Eye Research 2021;207(June):108607 [ Show Abstract ]

The purpose of this study was to develop a standardized, accurate and efficient method for estimating conjunctival goblet cell density (GCD) via optimizing sample storage conditions and quantification methods. Conjunctival impression cytology (CIC) membranes were collected from both eyes of 32 participants and were randomized to two storage durations (2-3 weeks, 6-7 weeks) and two storage container types (microcentrifuge tube, flat histology cassette). The CIC membranes were stained and subdivided into 25 areas (5 mm × 5 mm) for imaging and the GCs were counted under 200X magnification using three different methods: (1) full CIC membrane GC count of the 25 images with cell-counting software ("full"; reference method), (2) partial membrane GC count of 9 images with cell-counting software ("partial"), and (3) manual counting of the 25 images ("manual"). In all cases, GCD was determined by dividing the GC count by the counting area. The average time required for quantification was recorded to gauge efficiency. Results showed no significant difference in GC count between the two storage durations (p = 0.745) or storage container types (p = 0.552). The median (interquartile range (IQR)) time required to quantify a CIC membrane for the full, partial, and manual methods of GC counting, was 14.8(17.6), 4.6(5.2) and 5.0 (5.0) minutes, respectively. The agreement of GCD values between the full and manual methods (bias: 0.4, 95% LOA: [-4.6, 5.5]) was stronger than that comparing the full and partial methods (bias: 0.5, 95% LOA: [-18, 17]). All together, through systematic examination of key procedural variables, an optimized method for GCD quantification within 7 weeks of sample collection was outlined. Adaption of procedures described in this paper to facilitate accurate and efficient GCD quantification may serve as a valuable step in clinical trials investigating DED pathophysiology and/or novel DED treatment strategies.

2018

Yang,M., Luensmann,D., Fonn,D., Woods,J., Jones,D., Gordon,K., Jones,L. Myopia prevalence in Canadian school children: A pilot study Eye 2018;32(6):1042-1047 [ Show Abstract ]

Purpose: A pilot study to determine the prevalence of myopia, proportion of uncorrected myopia and pertinent environmental factors among children in a suburban region in Canada. Methods: Refraction with cycloplegia and ocular biometry were measured in children of two age groups. Myopia was considered at a spherical equivalent refraction (SER) ≤-0.50 D in at least one eye. Parents completed a questionnaire that captured the child's daily activities. Results: A total of 166 children completed the study (83 aged 6-8 and 83 aged 11-13). Myopia prevalence was 17.5% among the overall group, 6.0% among ages 6-8 and 28.9% among ages 11-13. Mean subjective SER in myopic children was -1.10 D (95% confidence interval (CI), -0.34 to -1.86 D) at ages 6-8 and -2.44 D (95% CI, -1.71 to -3.18 D) at ages 11-13. In this study, 34.5% of the myopic children were uncorrected, which represented 6.0% of the entire group of children. Mean axial length (AL) increased by 1.03 mm from ages 6-8 (mean 22.62 mm; 95% CI, 22.45 to 22.79 mm) to ages 11-13 (mean 23.65 mm; 95% CI, 23.45 to 23.84 mm; p < 0.01). The correlation coefficient between AL and SER was -0.618 (p < 0.01). Binary logistic regression between outdoor time and the prevalence of myopia showed that one additional hour of outdoor time per week lowered the odds of a child having myopia by 14.3% (p = 0.007). Conclusion: Myopia prevalence increased from 6% at ages 6-8 to 29% at ages 11-13. Thirty-five per cent of the myopes in this study were uncorrected. More time outdoors may be beneficial to protect against myopia onset.

Scientific Presentations

2020

Cheng X, Almaghshi M, Yang M, Shaw A, Brennan NA. Evaluating on-eye wavefront aberrations of a soft contact lens with an optical design simulating orthokeratology Investigative Ophthalmology & Vision Science 2020;61, 7:554 [ Show Abstract ][ PDF ]

Purpose : Orthokeratology (OK) has been shown to be effective in slowing myopia progression. The mechanism of action is hypothesized to be the resultant optical impact to the eye. However, a soft contact lens (SCL) designed to simulate the optical effect of OK (simOK) for myopia control was found to be ineffective in a randomized controlled myopia control trial. The purpose of this study was to evaluate on-eye wavefront aberrations of the simOK lens by comparing to that of successful OK patients.

Methods : Distance (4 m) and near (25 cm) wavefront aberrations were measured with an open-field Shack-Hartmann aberrometer in 8 OK-treated patients (bare eye only) and 20 non-OK subjects with bare eye (simOK-BE) and with simOK lens on-eye (simOK-LOE) between the age of 7 and 25 years. Zernike expansions of wavefront aberration functions to the 6th order were used to determine aberration coefficients for a series of pupil diameters. Zernike coefficient of primary spherical aberration (Z40), Root-Mean-Square (RMS) of 3rd order and total Higher Order Aberrations (HOA, 3rd – 6th orders) at a 5 mm aperture were compared between simOK-BE and SimOK-LOE and between OK and simOK-LOE. A general linear mixed model with a type I error of 0.05 was used for statistical analysis.

Results : Under a 5mm pupil and with a 4-m target, the means (SD) of Z40 were 0.054 (0.050), 0.350 (0.066), and 0.364 (0.212) microns in simOK-BE, simOK-LOE and OK, respectively. Compared to simOK-BE, Z40 was significantly increased with simOK-LOE with least-square-mean (LSM) difference of 0.297 micron (95% CI: 0.255, 0.338, p<0.001). There was no significant difference in Z40 between simOK-LOE and OK (LSM difference (95%CI): -0.034 micron (-0.148, 0.080), p=0.783). Similar results were found between conditions for near wavefront and for total 3rd order aberrations and total HOAs.

Conclusions : This exploratory study demonstrated that wearing SCL designed to simulate the optical impact of OK resulted in a significant increase of HOAs in the eye. The magnitude of HOAs, including primary spherical aberration and 3rd order aberrations, was similar to those of the OK patients. To fully characterize the on-eye optical performance of the simOK lens and understand the mechanism of action of OK, additional analysis of off-axis refraction and accommodative response with the simOK lens will be examined.

This is a 2020 ARVO Annual Meeting abstract.

2019

Yang M, Moezzi A, Woods J, Jones L. Comparing Strip Meniscometry to Tear Meniscus Height & Schirmer Test American Academy of Optometry, Orlando, 2019 [ Show Abstract ][ PDF ]

Purpose: Evaluation of tear volume is an important parameter for investigating aqueous deficient dry eye disease (DED). Historically, this has been achieved using Schirmer (SCH) strips or non-invasively using estimation of tear meniscus height (TMH). A method using strip meniscometry (SM) (SMTube, Shirakawa Factory, Tokyo, Japan) has recently been developed as a fast (5-second) in-office diagnostic test. The purpose of this study was to determine how tear volume assessed by SM compared to TMH and SCH in a mixed cohort of subjects with and without DED.

Methods: Both eyes of 27 participants (7 males; 20 females) aged between 21 and 64 (mean 40.7 years) underwent all measurements. TMH and non-invasive tear breakup time (NITBUT) were assessed using the Keratograph5M (Oculus, Germany). Subjects completed the ocular surface disease index (OSDI). SM was undertaken, and after a 1 hour delay, SCH (without anesthetic) was measured over five minutes. Subjective preference between SM and SCH was also collected. The correlation between SM and NITBUT, TMH and SCH were analysed.

Results: Only right eye data is presented. The mean (±SD) scores were: SM 5.6 (±3.2) mm; NITBUT 8.82 (±5.35) seconds; TMH 0.23 (±0.07) mm; SCH 22.2 (±10.1) mm. Mean OSDI was 13.1 (±9.3). The linear correlations (Pearson r) with SM were all low: NITBUT (0.479), TMH (0.006), SCH (0.301) and OSDI (0.075). 100% of participants preferred SM to SCH, citing the reasons for their preference as better comfort and shorter test time.

Conclusion: Strip meniscometry (SM) is a more rapid test compared to Schirmer test, and was found to be significantly more comfortable by the participants. However, given the low correlation with standard tear film evaluation tests its ability to discriminate between patients with and without DED requires further evaluation.

2016

Yang M, Luensmann D, Fonn D, Woods J, Gordon K, Jones L, Jones D. Myopia prevalence in canadian school children Optom Vis Sci 2016;93: E-abstract 165328 [ PDF ]

Professional Publications

2021

Ng AY, Yang M. Why you shouldn’t neglect eye care during the pandemic The Conversation 2021;March 7 [ Show Abstract ]

Since COVID-19 emerged, access to eye care has continued to change. Lockdowns and concerns about virus exposure have caused people of all ages to cancel and delay routine appointments, raising red flags among eye-care professionals. As the pandemic continues into its second year, can ocular health be neglected any longer?

Our team of optometrists and clinical scientists at the Centre for Ocular Research & Education (CORE) hear the confusion and concerns about people’s eyes during COVID-19. Addressing the most common questions — many of which we keep up to date at COVIDeyefacts.org — can help you and your family maintain the best vision while staying safe.

Yang M. CLEAR report summary: Medical Use of Contact Lenses https://contactlensupdate.com/2021/06/15/medical-use-of-contact-lenses/ 2021

2019

Yang M. Summary: IMI – Clinical Management Guidelines Report ContactLensUpdate.com 2019

2018

Yang M. Are contact lenses safe for children? ContactLensUpdate.com 2018

Yang M. Myopia: A Global Problem with a Local Solution Optik 2018, September: 38-42

2017

Yang M. Summary: Management and therapy report ContactLensUpdate.com 2017

2014

Yang M. Summary: Report of the Contact lens Interactions with the Ocular Surface and Adnexa Subcommittee ContactLensUpdate.com 2014

Books

2021

Jones L, Stahl U, Guthrie S, Yang M, Moezzi A, Thom M. Contact Lens Compendium: Contact Lenses & Solutions Available in America. Vol 2 2021.

Jones L, Stahl U, Guthrie S, Yang M, Moezzi A, Thom M. Contact Lens Compendium: Contact Lenses and Solutions Available in Canada. Vol 47 2021.

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.