Retinal vessels
Last reviewed: 23.04.2024
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Entering the eye in the center of the optic nerve, the retinal artery retina and the accompanying vein branch into four, supplying the four quadrants of the retina with blood: upper and lower nasal and upper and lower temporal. Vessels of the retina before their first branch are called vessels of the first order, from the first to the second branching - vessels of the third order. All these vessels are clearly visible in ophthalmoscopy. Smaller vessels (arterioles, venules and true capillaries) are not visible even with modern methods of ophthalmoscopy. The terminal capillaries of the retina consist of one layer of epithelium and they have no shells.
Capillaries of the retina spread in the inner layers and terminate in the layer of bipolar cells on the border with the first neuron (on the periphery). In this way, the retina will receive blood supply from two sources: the inner layer to the first neuron - from the central retinal artery system, and the first neuron from the vascular membrane.
The metabolic processes between the capillaries of the terminal capillaries and the cellular elements of the retina occur through the interstitial environment that surrounds each cell of the organ (including cells of the mesh shell). In this interstitial medium, the end capillaries receive substances necessary for the life and function of the cells. In the same interstitial medium, the products of their vital activity come from the cells. While reacting, some of the substances are destroyed, but in the intermediate environment there is always a sufficient and continuously replenished stock of the necessary ingredients for metabolism.
Each cell, each fiber and each capillary of the reticular shell is surrounded by an interstitial. It is an internal environment in which all necessary components are transported from the blood of the terminal capillaries to the nerve cells.
Thus, blood supply to all layers of the retina is due to one arterial system - the central artery of the retina. The terminal capillaries do not extend to the first neuron, but the circulation is combined for all nerve cells and fibers through interstitial colloidal substance. The function of the choroid is limited only to the supply of one layer of pigment epithelium.
[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12],