[Optic nerve microcirculation. III. Lamina cribrosa].

The architecture of the lamina cribrosa was investigated on the material of 160 optic nerves of people decreased at the age of 6 months to 80 years, free of pathological changes of circulation. The posterior segment of lamina cribrosa is supplied by arterial blood from: centripetal arterioles of the pia mater, ramifications from the secondary and tertiary posterior short ciliary arteries and from the longitudinal net of capillaries of the optic nerve. The central part of the lamina cribrosa is supplied by the twigs of the complete or incomplete vascular ring of Zinn-Haller or directly from secondary twigs of choroidal arteries. The anterior part of lamina cribrosa is vascularized by choroidal vessels and in a minor part by the vascular ring of Zinn-Haller. The circulation in the area of lamina cribrosa is integrally connected with the system of posterior short ciliary arteries and the arterioles of the internal vagina of the optic nerve. The central retinal artery does not give up any branches in this region. Similarly to other segments of the optic nerve there exists an individual variability in the system and course of the vessels in the lamina cribrosa. The vascular system of lamina cribrosa is connected anteriorly with the vessels of the paralaminar area of the optic disc which receive vascular branches from early ramifications of the central retinal artery (25 p.c. of cases).