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S. McCarthy, P. Megaw, I.G. Morgan; Dopamine Antagonists Block the Protective Effects of Brief Periods of Normal Vision Against Form–Deprivation Myopia . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1137.
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To test the theory that the protective effect of brief periods of normal vision, in the form–deprivation myopia (FDM) paradigm, is a result of an increase in dopamine release and stimulation of dopamine receptors.
At five days of age, chickens were fitted with translucent diffusers to induce FDM. Diffusers were removed at 11am daily and chickens were injected intravitreally with 10µL of a dopamine antagonist and placed in the light. Diffusers were replaced at 2pm. After 8 days, axial length was measured using A–scan ultrasonography.
As previously shown, 3 hours of diffuser–free vision in the light protects against the development of FDM . The protective effect of light could be blocked when antagonists were injected immediately prior to diffuser–free time in the light. Dopamine antagonists had no effect on growth when injected into normal eyes or eyes that wore diffusers constantly. The response was mediated through the D2 receptor subtype.
The protective effect of diffuser–free vision in the light can be blocked with injections of a D2–dopamine antagonist. This finding is consistent with the hypothesis that the protective effect of diffuser–free vision is due to a light–induced increased release of retinal dopamine. 1. Napper, G.A., et al., Vision Res, 1995. 35(9): p. 1337–1344.
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