Adrenergic receptor agonist inhibits lens-induced myopia in chicks

Adrenergic receptor agonist inhibits lens-induced myopia in chicksMezbah Uddin, Bing Zuo, KK Li, Chi-ho To, Dennis Y. TseCentre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China.AbstractPurpose: Previous studies suggested that alpha-adrenergic receptors may underly the inhibitory effect of atropine against myopia development. We aim to test the efficacy of α1A-adrenergic and α2A-adrenergic agonists for inhibiting myopia in a chicken model.Methods: Myopia was induced in the right eyes of all chicks using -10D single vision lenses for 7 days, while the left eyes were left untreated as a control. α1A agonist (metaraminol) and α2A agonist (lofexidine) were intravitreally injected at concentrations of 30, 100 and 300 nmol in 10 μl solution into the right eyes on days 0, 2, 4 and 6. Phosphate-buffered saline (PBS) was injected into the control eye. Refractive error was and ocular biometry was measured on days 0, 7 and 14.Results: Metaraminol significantly inhibited lens-induced myopia and reduced axial elongation in a dose-dependent manner. Intraocular difference (IOD) in refraction on day 7 were - 100 nmol: -3.43 ± 2.76D, p = 0.001, n = 19; 300 nmol: -2.61 ± 1.84D, p < 0.001, n = 14). Lofexidine significantly inhibited lens-induced myopia and reduced axial elongation at all tested concentration. IOD of refraction on day 7 were (30 nmol: -5.67 ± 2.64D, p = 0.0001, n = 14; 100 nmol: -4.25 ± 1.92D, p < 0.001, n = 13 and 300 nmol: -3.25 ± 1.92D, p < 0.001, n = 14, respectively. Induced myopia in the treated eyes showed significant recovery at day 14 following lens removal at day 7.Conclusion: α1A and α2A- adrenergic receptor agonists were effective against optically induced myopia in chicken.Keyword: Myopia, mataminarole, lofexidine, adrenergic receptor agonist, lens-induced myopia, refractive error.