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Nina Tran, Kevin Kuo, Christine F. Wildsoet; The interacting effects of form-deprivation and myopic defocus imposed locally on the central and peripheral retina in chick eyes. Journal of Vision 2002;2(10):42. doi: https://doi.org/10.1167/2.10.42.
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© ARVO (1962-2015); The Authors (2016-present)
INTRODUCTION: Young chick eyes are able to distinguish between, and compensate for, defocus induced by positive and negative lenses by adjusting their ocular growth. Diffusers, used to impose form deprivation, like negative lenses, increase ocular growth, and decrease the converse response to positive lenses when combined with them. These responses appear to be regulated by local retinal regions. The current study followed up on anecdotal evidence that the central and peripheral retinal regions are differentially sensitive to defocus and deprivation.
METHODS: Positive 10D lenses were used alone or combined with diffusing Bangerter filters (#0.4) that either covered the whole lens (12 mm, full diffusers), a central 4 mm zone or a 4 mm peripheral zone. They were fitted monocularly to 7 day chicks that had their refractive errors and ocular dimensions measured periodically over the following 6 days using i.r. refractometry and high frequency ultrasonography respectively. Both techniques measure central (on-axis) changes.
RESULTS: The +10 D lens alone produced choroidal thickening, reduced vitreous chamber depth and hyperopia as expected, while the lens/full diffuser combination produced only a small response. The lenses with partial diffusers produced intermediate responses, even though local regional control would predict reduced responses only for the central diffuser/lens combination.
CONCLUSION: The result for the full diffuser/lens combination supports the hypothesis that sharp vision is required for normal compensation to positive lenses The partial diffusers reduced the lens response, irrespective of whether only the central or only the peripheral regions of the lenses were covered by diffusers. This finding implies interactions between central and peripheral regions of the retina in terms of ocular growth regulation.
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