Myra McGuinness

Dr. Myra McGuinness

orcid

Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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28 July 2020 in Clinical & Experimental Ophthalmology
Verified
Journal Article
Open access
PDF file
FHFlora Hui
Flora Hui
JTJessica Tang
Jessica Tang
PWPete Williams
Pete Williams
MMMyra McGuinness
Myra McGuinness
XHXavier Hadoux
Xavier Hadoux
JCJonathan G. Crowston
Jonathan G. Crowston
Importance: Retinal ganglion cells endure significant metabolic stress in glaucoma but maintain capacity to recover function. Nicotinamide, a precursor of NAD+, is low in serum of glaucoma patients and its supplementation provides robust protection of retinal ganglion cells in preclinical models. However, the potential of nicotinamide in human glaucoma is unknown.Background: To examine the effects of nicotinamide on inner retinal function in glaucoma, in participants receiving concurrent glaucoma therapy.Design: Crossover, double‐masked, randomized clinical trial. Participants recruited from two tertiary care centres.Participants: Fifty‐seven participants, diagnosed and treated for glaucoma.Methods: Participants received oral placebo or nicotinamide and reviewed six‐weekly. Participants commenced 6 weeks of 1.5 g/day then 6 weeks of 3.0 g/day followed by crossover without washout. Visual function measured using electroretinography and perimetry.Main outcome measures: Change in inner retinal function, determined by photopic negative response (PhNR) parameters: saturated PhNR amplitude (Vmax), ratio of PhNR/b‐wave amplitude (Vmax ratio).Results: PhNR Vmax improved beyond 95% coefficient of repeatability in 23% of participants following nicotinamide vs 9% on placebo. Overall, Vmax improved by 14.8% [95% CI: 2.8%, 26.9%], (P = .02) on nicotinamide and 5.2% [−4.2%, 14.6%], (P = .27) on placebo. Vmax ratio improved by 12.6% [5.0%, 20.2%], (P = .002) following nicotinamide, 3.6% [−3.4%, 10.5%], (P = .30) on placebo. A trend for improved visual field mean deviation was observed with 27% improving ≥1 dB on nicotinamide and fewer deteriorating (4%) compared to placebo (P = .02).Conclusions: Nicotinamide supplementation can improve inner retinal function in glaucoma. Further studies underway to elucidate the effects of long‐term nicotinamide supplementation.

1 June 2019 in Ophthalmology
Verified
Journal Article
Open access
RGRobyn Guymer
Robyn Guymer
ZWZhichao Wu
Zhichao Wu
LHLauren A.B. Hodgson
Lauren A.B. Hodgson
ECEmily Caruso
Emily Caruso
KBKate H. Brassington
Kate H. Brassington
CLChi Luu
Chi Luu
There is an urgent need for a more effective intervention to slow or prevent progression of age-related macular degeneration (AMD) from its early stages to vision-threatening late complications. Subthreshold nanosecond laser (SNL) treatment has shown promise in preclinical studies and a pilot study in intermediate AMD (iAMD) as a potential treatment. We aimed to evaluate the safety of SNL treatment in iAMD and its efficacy for slowing progression to late AMD. The Laser Intervention in Early Stages of Age-Related Macular Degeneration (LEAD) study is a 36-month, multicenter, randomized, sham-controlled trial. Two hundred ninety-two participants with bilateral large drusen and without OCT signs of atrophy. Participants were assigned randomly to receive Retinal Rejuvenation Therapy (2RT®; Ellex Pty Ltd, Adelaide, Australia) SNL or sham treatment to the study eye at 6-monthly intervals. The primary efficacy outcome was the time to development of late AMD defined by multimodal imaging (MMI). Safety was assessed by adverse events. Overall, progression to late AMD was not slowed significantly with SNL treatment compared with sham treatment (adjusted hazard ratio [HR], 0.61; 95% confidence interval [CI], 0.33-1.14; P = 0.122). However, a post hoc analysis showed evidence of effect modification based on the coexistence of reticular pseudodrusen (RPD; adjusted interaction P = 0.002), where progression was slowed for the 222 participants (76.0%) without coexistent RPD at baseline (adjusted HR, 0.23; 95% CI, 0.09-0.59; P = 0.002), whereas an increased progression rate (adjusted HR, 2.56; 95% CI, 0.80-8.18; P = 0.112) was observed for the 70 participants (24.0%) with RPD with SNL treatment. Differences between the groups in serious adverse events were not significant. In participants with iAMD without MMI-detected signs of late AMD, no significant difference in the overall progression rate to late AMD between those receiving SNL and sham treatment were observed. However, SNL treatment may have a role in slowing progression for those without coexistent RPD and may be inappropriate in those with RPD, warranting caution when considering treatment in clinical phenotypes with RPD. Our findings provide compelling evidence for further trials of the 2RT® laser, but they should not be extrapolated to other short-pulse lasers.

1 May 2020 in Ophthalmology
Verified
Journal Article
Closed access
CNCallum Narita
Callum Narita
ZWZhichao Wu
Zhichao Wu
PRPhilip J. Rosenfeld
Philip J. Rosenfeld
JYJin Yang
Jin Yang
CLCancan Lyu
Cancan Lyu
RGRobyn Guymer
Robyn Guymer

19 May 2022 in Ophthalmology
Verified
Journal Article
Open access
SSSumeer Singh
Sumeer Singh
MMMyra McGuinness
Myra McGuinness
AAAndrew J. Anderson
Andrew J. Anderson
LDLaura Downie
Laura Downie
To evaluate the efficacy and safety of interventions for treating eye strain related to computer use relative to placebo or no treatment. Computer use is pervasive and often associated with eye strain, referred to as computer vision syndrome (CVS). Currently, no clinical guidelines exist to help practitioners provide evidence-based advice about CVS treatments, many of which are marketed directly to patients. This systematic review and meta-analysis was designed to help inform best practice for eye care providers. Eligible randomized controlled trials (RCTs) were identified in Ovid MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and trial registries, searched from inception through November 23, 2021. Eligible studies were appraised for risk of bias and were synthesized. The certainty of the body of evidence was judged using the Grading of Recommendations, Assessment, Development, and Evaluation system. Standardized mean differences (SMDs) were used when differently scaled measures were combined. Forty-five RCTs, involving 4497 participants, were included. Multifocal lenses did not improve visual fatigue scores compared with single-vision lenses (3 RCTs; SMD, 0.11; 95% confidence interval [CI], -0.14 to 0.37; P = 0.38). Visual fatigue symptoms were not reduced by blue-blocking spectacles (3 RCTs), with evidence judged of low certainty. Relative to placebo, oral berry extract supplementation did not improve visual fatigue (7 RCTs; SMD, -0.27; 95% CI, -0.70 to 0.16; P = 0.22) or dry eye symptoms (4 RCTs; SMD, -0.10; 95% CI, -0.54 to 0.33; P = 0.65). Likewise, berry extract supplementation had no significant effects on critical flicker-fusion frequency (CFF) or accommodative amplitude. Oral omega-3 supplementation for 45 days to 3 months improved dry eye symptoms (2 RCTs; mean difference [MD], -3.36; 95% CI, -3.63 to -3.10 on an 18 unit scale; P < 0.00001) relative to placebo. Oral carotenoid supplementation improved CFF (2 RCTs; MD, 1.55 Hz; 95% CI, 0.42 to 2.67 Hz; P = 0.007) relative to placebo, although the clinical significance of this finding is unclear. We did not identify high-certainty evidence supporting the use of any of the therapies analyzed. Low-certainty evidence suggested that oral omega-3 supplementation reduces dry eye symptoms in symptomatic computer users.

1 August 2018 in American Journal of Ophthalmology
Verified
Journal Article
Closed access
MOMali Okada
Mali Okada
RKRathika Kandasamy
Rathika Kandasamy
ECElaine W. Chong
Elaine W. Chong
MMMyra McGuinness
Myra McGuinness
RGRobyn Guymer
Robyn Guymer

1 October 2020 in Ophthalmology
Verified
Journal Article
Closed access
JRJohn R. Rocke
John R. Rocke
MMMyra McGuinness
Myra McGuinness
WAWilliam K. Atkins
William K. Atkins
LFLewis Fry
Lewis Fry
JKJack X. Kane
Jack X. Kane
TEThomas L. Edwards
Thomas L. Edwards