Amber light treatment produces hyperopia in tree shrews

Khanal, Safal; Norton, Thomas T.; Gawne, Timothy J.

doi:10.1111/opo.12853

Cited by 10 publications

(14 citation statements)

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“… 62 , 63 More recently, it was shown that amber light, spanning a relatively broad band of frequencies but omitting those shorter than 500 nm, also promotes hyperopia in tree shrews. 64 However, long-wavelength light has not been consistently found to slow eye growth in the other common animal models of myopia, and in fact, red light rearing induces eye growth in chickens, 54 , 65 , 66 guinea pigs, 67 – 70 and fish. 71 , 72 Red light has not been widely studied in mice, although one study did suggest that red light promotes hyperopia in this species.…”

Section: Imi Digest—experimental Models Of Emmetropization and Myopiamentioning

confidence: 99%

IMI 2023 Digest

Sankaridurg

Berntsen

Bullimore

et al. 2023

Invest. Ophthalmol. Vis. Sci.

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Myopia is a dynamic and rapidly moving field, with ongoing research providing a better understanding of the etiology leading to novel myopia control strategies. In 2019, the International Myopia Institute (IMI) assembled and published a series of white papers across relevant topics and updated the evidence with a digest in 2021. Here, we summarize findings across key topics from the previous 2 years. Studies in animal models have continued to explore how wavelength and intensity of light influence eye growth and have examined new pharmacologic agents and scleral cross-linking as potential strategies for slowing myopia. In children, the term premyopia is gaining interest with increased attention to early implementation of myopia control. Most studies use the IMI definitions of ≤−0.5 diopters (D) for myopia and ≤−6.0 D for high myopia, although categorization and definitions for structural consequences of high myopia remain an issue. Clinical trials have demonstrated that newer spectacle lens designs incorporating multiple segments, lenslets, or diffusion optics exhibit good efficacy. Clinical considerations and factors influencing efficacy for soft multifocal contact lenses and orthokeratology are discussed. Topical atropine remains the only widely accessible pharmacologic treatment. Rebound observed with higher concentration of atropine is not evident with lower concentrations or optical interventions. Overall, myopia control treatments show little adverse effect on visual function and appear generally safe, with longer wear times and combination therapies maximizing outcomes. An emerging category of light-based therapies for children requires comprehensive safety data to enable risk versus benefit analysis. Given the success of myopia control strategies, the ethics of including a control arm in clinical trials is heavily debated. IMI recommendations for clinical trial protocols are discussed.

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Section: Imi Digest—experimental Models Of Emmetropization and Myopiamentioning

confidence: 99%

IMI 2023 Digest

Sankaridurg

Berntsen

Bullimore

et al. 2023

Invest. Ophthalmol. Vis. Sci.

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“…Longer axial length is associated with increased risk of vision impairment from retinal detachment, myopic macular degeneration, and choroidal neovascularization . Given these potential complications, many treatments to control myopia are being prescribed including topical atropine, soft multifocal contact lenses, overnight orthokeratology, specialized spectacle lenses, increased outdoor activity, and chromatic interventions . Recently, low-dose atropine eye drops have also been used in Hong Kong to delay the onset of myopia in some children …”

Section: Introductionmentioning

confidence: 99%

Low-Dose 0.01% Atropine Eye Drops vs Placebo for Myopia Control

et al. 2023

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ImportanceControlling myopia progression is of interest worldwide. Low-dose atropine eye drops have slowed progression in children in East Asia.ObjectiveTo compare atropine, 0.01%, eye drops with placebo for slowing myopia progression in US children.Design, Setting, and ParticipantsThis was a randomized placebo-controlled, double-masked, clinical trial conducted from June 2018 to September 2022. Children aged 5 to 12 years were recruited from 12 community- and institution-based practices in the US. Participating children had low to moderate bilateral myopia (−1.00 diopters [D] to −6.00 D spherical equivalent refractive error [SER]).InterventionEligible children were randomly assigned 2:1 to 1 eye drop of atropine, 0.01%, nightly or 1 drop of placebo. Treatment was for 24 months followed by 6 months of observation.Main Outcome MeasuresAutomated cycloplegic refraction was performed by masked examiners. The primary outcome was change in SER (mean of both eyes) from baseline to 24 months (receiving treatment); other outcomes included change in SER from baseline to 30 months (not receiving treatment) and change in axial length at both time points. Differences were calculated as atropine minus placebo.ResultsA total of 187 children (mean [SD] age, 10.1 [1.8] years; age range, 5.1-12.9 years; 101 female [54%]; 34 Black [18%], 20 East Asian [11%], 30 Hispanic or Latino [16%], 11 multiracial [6%], 6 West/South Asian [3%], 86 White [46%]) were included in the study. A total of 125 children (67%) received atropine, 0.01%, and 62 children (33%) received placebo. Follow-up was completed at 24 months by 119 of 125 children (95%) in the atropine group and 58 of 62 children (94%) in the placebo group. At 30 months, follow-up was completed by 118 of 125 children (94%) in the atropine group and 57 of 62 children (92%) in the placebo group. At the 24-month primary outcome visit, the adjusted mean (95% CI) change in SER from baseline was −0.82 (−0.96 to −0.68) D and −0.80 (−0.98 to −0.62) D in the atropine and placebo groups, respectively (adjusted difference = −0.02 D; 95% CI, −0.19 to +0.15 D; P = .83). At 30 months (6 months not receiving treatment), the adjusted difference in mean SER change from baseline was −0.04 D (95% CI, −0.25 to +0.17 D). Adjusted mean (95% CI) changes in axial length from baseline to 24 months were 0.44 (0.39-0.50) mm and 0.45 (0.37-0.52) mm in the atropine and placebo groups, respectively (adjusted difference = −0.002 mm; 95% CI, −0.106 to 0.102 mm). Adjusted difference in mean axial elongation from baseline to 30 months was +0.009 mm (95% CI, −0.115 to 0.134 mm).Conclusions and RelevanceIn this randomized clinical trial of school-aged children in the US with low to moderate myopia, atropine, 0.01%, eye drops administered nightly when compared with placebo did not slow myopia progression or axial elongation. These results do not support use of atropine, 0.01%, eye drops to slow myopia progression or axial elongation in US children.Trial RegistrationClinicalTrials.gov Identifier: NCT03334253

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“…The antimyopiagenic or hyperopia-promoting effect of narrowband red light in tree shrews and monkeys could be a consequence of the loss of ability or efficiency of the emmetropization mechanism to use longitudinal chromatic aberration-derived wavelength cues to accurately guide eye growth. At least for these two animal models, it has been proposed that narrowband red light tricks the emmetropization mechanism into inferring that the red light is in sharper focus than the blue light (assuming no blue light equates to no blue image sharpness), signaling the production of STOP signals that promote slower eye growth and hyperopia development 74 . If this were true, any light that avoids the stimulation of short-wavelength–sensitive cones should produce a similar myopia control effect.…”

Section: Background: the Value Of Lightmentioning

confidence: 99%

Repeated Low-level Red-light Therapy: The Next Wave in Myopia Management?

Salzano,

Khanal,

Cheung

et al. 2023

Optom Vis Sci

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Significance Exposure to long-wavelength light has been proposed as a potential intervention to slow myopia progression in children. This article provides an evidence-based review of the safety and myopia control efficacy of red light and discusses the potential mechanisms by which red light may work to slow childhood myopia progression. The spectral composition of the ambient light in the visual environment has powerful effects on eye growth and refractive development. Studies in mammalian and primate animal models (macaque monkeys and tree shrews) have shown that daily exposure to long wavelength (red or amber) light promotes slower eye growth and hyperopia development and inhibits myopia induced by form deprivation or minus lens wear. Consistent with these results, several recent randomized controlled clinical trials in Chinese children have demonstrated that exposure to red light for three minutes twice a day significantly reduces myopia progression and axial elongation. These findings have collectively provided strong evidence for the potential of using red light as a myopia control intervention in clinical practice. However, several questions remain unanswered. In this article, we review the current evidence on the safety and efficacy of red light as a myopia control intervention, describe potential mechanisms, and discuss some key unresolved issues that require consideration before red light can be broadly translated into myopia control in children.

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Amber light treatment produces hyperopia in tree shrews

Cited by 10 publications

References 68 publications

IMI 2023 Digest

IMI 2023 Digest

Low-Dose 0.01% Atropine Eye Drops vs Placebo for Myopia Control

Repeated Low-level Red-light Therapy: The Next Wave in Myopia Management?

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