PurposeThe hypothesis that outdoor exposure might protect against myopia has generated much interest, although available data find only modest clinical efficacy. We tested the effect of outdoor rearing on form-deprivation myopia in chicks, a myopia model markedly inhibited by high-intensity indoor laboratory lighting.MethodsUnilaterally goggled cohorts of White Leghorn chicks were maintained in a species-appropriate, outdoor rural setting during daylight hours to the extent permitted by weather. Control chicks were reared indoors with incandescent lighting. Besides ocular refraction and ultrasound, we determined dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) content in retina and vitreous and measured mRNA expression levels of selected clock and circadian rhythm-related genes in the retina/RPE.ResultsMyopia developed in the goggled eyes of all cohorts. Whereas outdoor rearing lessened myopia by 44% at 4 days, a protective effect was no longer evident at 11 days. Outdoor rearing had no consistent effect on retinal or vitreous content of dopamine or DOPAC. Conforming to prior data on form-deprivation myopia, retina and vitreous levels of DOPAC were reduced in goggled eyes. Compared with contralateral eyes, the retinal expression of clock and circadian rhythm-related genes was modestly altered in myopic eyes of chicks reared indoors or outdoors.ConclusionsOutdoor rearing of chicks induces only a partial decrease of goggle-induced myopia that is not maintained, without evidence that retinal dopamine metabolism accounts for the partial myopia inhibition under these outdoor conditions. Although modest, alterations in retinal gene expression suggest that studying circadian signals might be informative for understanding refractive mechanisms.

Dans l'ordre des Herpesvirales et la famille des Herpesviridae, les herpèsvirus des oiseaux, regroupés dans la sous-famille des Alphaherpesvirinae, infectent de nombreuses espèces aviaires (poulets, dindes, canards, pigeons, les perroquets, aigles, cigognes, faucons, grues, colins, cormorans, pingouins, hiboux…). Les principales herpèsviroses aviaires sont la maladie de Marek oncogène (Gallid herpesvirus 2, genre Mardivirus), la laryngotrachéite infectieuse (Gallid herpesvirus 1, genre Iltovirus), l'entérite à virus ou peste du canard (Anatid Herpesvirus, non classé, mais proche des genres In the order of Herpesvirales and the family of Herpesviridae, herpeviruses of birds, grouped in the subfamily of Alphaherpesvirinae, infect many avians,