ABSTRACT
Correspondence: J.Greenwood, Department of Clinical Ophthalmology, Institute of Ophthalmology, University College London, Bath Street, London, EC1V 9EL, UK; Tel: +44 171 608 6858; Fax: +44 171 608 6810; E-mail: j.greenwood@ucl.ac.uk
INTRODUCTION
The regulation of blood flow to the retina is a critical factor in the maintenance of normal retinal function and any failure of the processes regulating retinal perfusion is likely to have a profound effect on retinal homeostasis. In particular, dysfunctional retinal blood flow has been associated with a variety of retinal disorders including glaucoma and hypertensive retinopathy. The retina receives its blood supply from two separate and distinct vascular beds. In general, the choroidal vasculature supplies the outer, avascular region of the retina (the photoreceptor layer) by diffusion across the retinal pigmented epithelium (RPE). The retinal vasculature is normally confined to the inner retina as far as the boundary between the inner nuclear layer and outer plexiform layer, and supplies these inner layers as well as 10% of the oxygen requirements of the photoreceptors during dark adaptation (Ahmed et al., 1993).
