Initial observations on the ocular microcirculation in man. I. The anterior segment and extraocular muscles.

Gold-coated, plastic corrosion casts of the human ocular microcirculation were studied by scanning electron microscopy to define the angioarchitecture of the anterior segment, ciliary processes, and extraocular muscles. Several arterial branches from the major arterial circle (MAC) supplied each ciliary process. The afferent arterial supply may be regulated by a sphincter mechanism at its branch point from the MAC. The ciliary processes and ciliary muscle seem to be drained by iris veins and prominent venules, one of which is present between each pair of ciliary processes, and directly into pars plana veins. The predominant drainage channel of the ciliary processes is directly into the pars planar veins; the ciliary muscle seems to be drained by the other two routes primarily. The extraocular muscles possess a rich blood supply. No anastomoses of the anterior ciliary arteries with the MAC were noted, although they did contribute to the blood supply of the iris, ciliary muscle, and episcleral vascular complex.