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Yan Zhang, Hui Zhang, Christine Frances Wildsoet; Effects of Defocus and Image Degradation on Eye Growth and BMP2 Gene Expression in Chick Retinal Pigment Epithelium. Invest. Ophthalmol. Vis. Sci. 201657(12):.
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© 2017 Association for Research in Vision and Ophthalmology.
This study investigated the effects of defocus and image degradation on eye growth and Bone Morphogenetic Protein-2 (BMP2) gene expression in chick retinal pigment epithelium (RPE)
14-day old White-Leghorn chicks wore monocular +10, -10 D or plano lenses that were either left uncovered or overlaid with a Bangerter filter (either 0.6, 0.1 or <0.1), for up to 6 days. Refractive errors and ocular dimensions were measured by retinoscopy and high-resolution frequency A-scan ultrasonography respectively, before (baseline) and after 6 days of treatment. The RPE was isolated from a subset undergoing 2 hours of treatment and BMP2 gene expression quantified with qPCR.
The +10 D lens alone or combined with either 0.6 or 0.1 Bangerter filters (BF) (+10D/BF0.6 or +10D/BF0.1) induced hyperopia, thicker choroids (CT), and shorter vitreous chamber depths (VCD), and axial lengths (AL) in treated eyes compare to contralateral controls after 6 days of treatment; in contrast, +10D/BF<0.1 induced myopia, longer AL and VCD, and thinner CT in treated eyes over the same time (Table 1). After 2 h of treatment, the BMP2 gene was up-regulated 6.35, 4.25 and 19.25 folds with +10D, +10D/BF0.6 and +10D/BF0.1 respectively, but down-regulated 3.47 folds with +10D/BF<0.1 (Table 1). All treatments involving the -10 D lens alone or combined with a BF (0.6, 0.1 or <0.1), induced myopia in treated eyes, which showed longer AL and VCD, and thinner CT after 6 days of treatment, as well as down-regulation of BMP2 gene expression after 2 h of treatment (Table 2). Plano lenses alone did not affect eye growth or BMP2 gene expression, while the plano/BF<0.1 combination induced myopia, longer AL, VCD, and thinner CT after 6 days, and BMP2 gene expression was correspondingly down-regulated 3.78 folds after 2 h of treatment (Table 3).
This study provides evidence that significant image degradation (most dense BF), abolishes the ability of the retina to decode imposed myopic defocus, with the effect of image degradation dominating, both in terms of eye growth and RPE-BMP2 gene expression. These results also provide further supporting evidence for a role of BMP2 in eye growth regulation.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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