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The Foveal Avascular Region of Developing Human Retina
J. M. Provis, PhD;
A. E. Hendrickson, PhD
Arch Ophthalmol. 2008;126(4):507-511.
Objective To study the development of the perifoveal retinal vasculature.
Methods We studied 7 retinas aged between 26 weeks' gestation and 1 week postnatal (41 weeks' gestation). Sections were imaged using high-resolution digital photography and blood vessel profiles identified at 200% to 300% magnification. Flat mounts were immunolabeled using antibodies to CD31 and factor VIII to identify blood vessels and antibodies to rhodopsin to identify the rod-free zone.
Results The foveal region was identified by the absence of rod photoreceptors in the outer retina and/or presence of a shallow depression in the inner retina. The whole mount at 26 weeks' gestation showed a blood vessel–free region centered on the rod-free zone that was open along the horizontal meridian on the temporal side. At 37 weeks' gestation, the foveal avascular zone formed a complete circle. In sections, the foveal avascular zone was approximately 500 µm in diameter at 35 weeks' gestation and 300 to 350 µm at 40 weeks' gestation; in whole mounts, it was 150 to 170 µm in diameter at 37 and 41 weeks' gestation.
Conclusions The foveal region is normally avascular during development, as in adult life. We found no evidence of foveal vascularization during development of the human retina.
Clinical Relevance Instances of vascularization of the foveal region are not due to failed regression of a transient vasculature.
Author Affiliations: ARC Centre of Excellence in Vision Science, Australian National University, Canberra, Australia (Dr Provis); and Departments of Biological Structure and Ophthalmology, University of Washington, Seattle (Dr Hendrickson).
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