Light Inhibits Lens-Induced Myopia through an Intensity-Dependent Dopaminergic Mechanism
Purpose: Bright light exposure has been postulated to underlie the ability of time spent outdoors to prevent the development of myopia in humans. In support of this, bright light inhibits the development of form-deprivation myopia (FDM) in all species studied. While lens-induced myopia (LIM) is also...
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Elsevier
2025-09-01
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| Series: | Ophthalmology Science |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2666914525000776 |
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| author | Cindy Karouta, PhD Kate Thomson, PhD Ian Morgan, PhD Regan Ashby, PhD |
| author_facet | Cindy Karouta, PhD Kate Thomson, PhD Ian Morgan, PhD Regan Ashby, PhD |
| author_sort | Cindy Karouta, PhD |
| collection | DOAJ |
| description | Purpose: Bright light exposure has been postulated to underlie the ability of time spent outdoors to prevent the development of myopia in humans. In support of this, bright light inhibits the development of form-deprivation myopia (FDM) in all species studied. While lens-induced myopia (LIM) is also inhibited by bright light in most species, it remains unclear whether this is brought about in an intensity-dependent manner and whether dopamine (DA) plays the same critical role in this paradigm as is seen in FDM. Design: An experimental study. Subjects: White Leghorn chickens (Gallus gallus). Methods: To examine the effect of light on LIM, chicks fit with lenses of −10 diopters were exposed to 500, 20 000, or 40 000 lux for 14 days (n = 6 per group). To assess the role of DA, its levels were measured 30 minutes after light exposure in previously dark-adapted animals over 6 light intensities (between dark and 40 000 lux). In a separate experiment, a D1-like (SCH-23390) or D2-like (spiperone) receptor antagonist was administered (once daily) to chicks wearing negative lenses under 40 000 lux (n = 5 to 6 per group) for a period of 5 days. Main Outcome Measures: Refraction (infrared photoretinoscopy), axial length (A-scan ultrasonography), and DA levels (liquid chromatography-tandem mass spectrometry). Results: Bright light inhibited LIM in an intensity-dependent manner (P < 0.05) but did not prevent full compensation. The protection afforded by bright light was significantly reduced by administration of spiperone (D2-like, P < 0.05), but not SCH-23390 (D1-like, P = 0.77). Retinal DA levels showed an intensity-dependent increase (P < 0.05). Conclusions: As previously observed for FDM, bright light can inhibit the development of LIM in an intensity-dependent manner. This protection occurs, at least in part, via a DA-dependent mechanism. However, bright light's inability to prevent compensation to negative lenses is indicative of mechanistic differences between the 2 experimental models of myopia. These differences are most likely linked to the presence of a defocus-driven end point for growth in LIM that is not present in FDM. Financial Disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article. |
| format | Article |
| id | doaj-art-44228d27a89b40a08e528f45d831b51b |
| institution | OA Journals |
| issn | 2666-9145 |
| language | English |
| publishDate | 2025-09-01 |
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| series | Ophthalmology Science |
| spelling | doaj-art-44228d27a89b40a08e528f45d831b51b2025-08-20T02:16:18ZengElsevierOphthalmology Science2666-91452025-09-015510077910.1016/j.xops.2025.100779Light Inhibits Lens-Induced Myopia through an Intensity-Dependent Dopaminergic MechanismCindy Karouta, PhD0Kate Thomson, PhD1Ian Morgan, PhD2Regan Ashby, PhD3Biomedical Science, Faculty of Science and Technology, University of Canberra, ACT, Australia; Correspondence: Cindy Karouta, PhD, University of Canberra, Biomedical Science, 11 Kirinari Street, Bruce, Canberra, ACT, 2617, Australia.Biomedical Science, Faculty of Science and Technology, University of Canberra, ACT, AustraliaResearch School of Biology, Australian National University, ACT, AustraliaBiomedical Science, Faculty of Science and Technology, University of Canberra, ACT, Australia; Research School of Biology, Australian National University, ACT, AustraliaPurpose: Bright light exposure has been postulated to underlie the ability of time spent outdoors to prevent the development of myopia in humans. In support of this, bright light inhibits the development of form-deprivation myopia (FDM) in all species studied. While lens-induced myopia (LIM) is also inhibited by bright light in most species, it remains unclear whether this is brought about in an intensity-dependent manner and whether dopamine (DA) plays the same critical role in this paradigm as is seen in FDM. Design: An experimental study. Subjects: White Leghorn chickens (Gallus gallus). Methods: To examine the effect of light on LIM, chicks fit with lenses of −10 diopters were exposed to 500, 20 000, or 40 000 lux for 14 days (n = 6 per group). To assess the role of DA, its levels were measured 30 minutes after light exposure in previously dark-adapted animals over 6 light intensities (between dark and 40 000 lux). In a separate experiment, a D1-like (SCH-23390) or D2-like (spiperone) receptor antagonist was administered (once daily) to chicks wearing negative lenses under 40 000 lux (n = 5 to 6 per group) for a period of 5 days. Main Outcome Measures: Refraction (infrared photoretinoscopy), axial length (A-scan ultrasonography), and DA levels (liquid chromatography-tandem mass spectrometry). Results: Bright light inhibited LIM in an intensity-dependent manner (P < 0.05) but did not prevent full compensation. The protection afforded by bright light was significantly reduced by administration of spiperone (D2-like, P < 0.05), but not SCH-23390 (D1-like, P = 0.77). Retinal DA levels showed an intensity-dependent increase (P < 0.05). Conclusions: As previously observed for FDM, bright light can inhibit the development of LIM in an intensity-dependent manner. This protection occurs, at least in part, via a DA-dependent mechanism. However, bright light's inability to prevent compensation to negative lenses is indicative of mechanistic differences between the 2 experimental models of myopia. These differences are most likely linked to the presence of a defocus-driven end point for growth in LIM that is not present in FDM. Financial Disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.http://www.sciencedirect.com/science/article/pii/S2666914525000776MyopiaLightDopamineTime outdoorsLens-induced myopia |
| spellingShingle | Cindy Karouta, PhD Kate Thomson, PhD Ian Morgan, PhD Regan Ashby, PhD Light Inhibits Lens-Induced Myopia through an Intensity-Dependent Dopaminergic Mechanism Ophthalmology Science Myopia Light Dopamine Time outdoors Lens-induced myopia |
| title | Light Inhibits Lens-Induced Myopia through an Intensity-Dependent Dopaminergic Mechanism |
| title_full | Light Inhibits Lens-Induced Myopia through an Intensity-Dependent Dopaminergic Mechanism |
| title_fullStr | Light Inhibits Lens-Induced Myopia through an Intensity-Dependent Dopaminergic Mechanism |
| title_full_unstemmed | Light Inhibits Lens-Induced Myopia through an Intensity-Dependent Dopaminergic Mechanism |
| title_short | Light Inhibits Lens-Induced Myopia through an Intensity-Dependent Dopaminergic Mechanism |
| title_sort | light inhibits lens induced myopia through an intensity dependent dopaminergic mechanism |
| topic | Myopia Light Dopamine Time outdoors Lens-induced myopia |
| url | http://www.sciencedirect.com/science/article/pii/S2666914525000776 |
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