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Why does retinal artery occlusion occur?

Due to differences in the time between angiography and obstruction, the location and degree of obstruction, and the different compensation and reconstruction conditions of blood circulation after obstruction, the angiographic findings vary. This can range from complete arterial non-perfusion, sluggish filling, non-perfusion of small branches, to completely normal filling. Generally speaking, there are the following manifestations: Fluorescence angiography findings in the early stage of the disease: Clinically, there is no opportunity to perform fluorescein angiography immediately at the beginning of the obstruction. The so-called findings in the early stage of the disease actually refer to Angiographic changes occurring hours or days after onset. , When the main trunk is completely blocked, the retinal artery is not perfused with fluorescent dye, but the capillaries of the optic disc, which are supplied by the ciliary artery, are quickly filled with pigment and significantly expand, forming side branch anastomoses, and quickly reflux to the root of the central vein on the optic disc. , causing the dye to accumulate in the proximal end of the main vein. At the same time, a special reverse flow phenomenon occurs, that is, the dye is retrogradely filled from the main vein to the external optic disc vein branch. , When the complete obstruction of the main trunk is suddenly relieved, or when the main trunk is incompletely blocked, the angiographic findings vary depending on the degree of obstruction at the time of angiography. Those with more severe obstruction show slow fluorescence filling, and the retinal artery completes the circulation time. In normal eyes, it is about 1 to 2 seconds, and can be extended to 30 to 40 seconds in blocked arteries. The time for fluorescence to appear in veins is also very slow. Normally, the difference between the arterial phase and the early venous phase is only 1 to 2 seconds, but at this time, it can be extended to 30 to 40 seconds. The venous fluorescence is dim or granular, indicating severe poor blood circulation. For those with mild obstruction, the arterial and venous filling time is slightly longer or completely normal. , During angiography of complete branch obstruction, it can be seen that the blood flow to the obstruction is suddenly interrupted, and there is fluorescent leakage from the wall of the tube. Another indication of complete branch obstruction is retrograde filling. Since the pressure at the distal end of the blocked branch is quite low, it is possible for blood to flow back from the capillaries. Therefore, on the fluorescent film in the early stage of the blockage, it can be seen that the dye perfusion at the distal end of the artery is earlier than that at the proximal end of the blockage. , Incomplete obstruction of the branch, and there is no fluorescent leakage from the wall of the obstruction. The fluorescence filling time of this arterial branch is slightly longer than other normal branches or completely normal. , The late stage of the disease refers to weeks or even months after the obstruction occurs.

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