[Functional differences in the microcirculatory units of the eye]

This review describes the most important regions of microcirculation within the eye - their architecture as well as their function. A special emphasis is put on the functional heterogeneity of the microvessels and their role regarding the specific functions localised within the different regions of the eye (e.g. oxygen release by the iris capillaries, production of aqueous humor within the ciliary processes). The microvasculature of choroidea and retina will be described in more detail. The precise adjustment of the blood flow to the functional needs of the inner retina is a very important aspect in the retinal vessels. Here, also pericytes can influence the vessel calibre like in the brain capillaries. Very important is the vascular reaction in general to states of hypoxia, especially to the hypoxic and radical producing states within the photoreceptors. The following reaction of neovascularisation will also be examined. Finally, we describe the metabolic situation of the ganglion cells and nerve fibers leading to and within the optic cup also with regard to glaucoma.