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X. Kong, X. Sun, C. Jiang; Study of Retinal Microvessels in Chronic High Intraocular Pressure Monkeys and Patients. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5859.
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To investigate the changes in retinal microvessels under high intraocular pressure using the rhesus monkey high intraocular pressure model and to compare the difference of macular capillaries between normal controls and glaucomatous patients by using one high distinguishable method called adptive optics
I.The trabecular meshwork of the adult rhesus monkey was cauterized by laser to induce increased intraocular pressures with different degrees of damage. The eyeballs were enucleated, and the optic nerves were stained with toluidine blue in semi-thick slices. Part of the retina was observed under electron microscope, and the rest was stained by the ADPase method. The damage levels of the optic nerve were evaluated by axon count, and the pathological appearance of the macular capillaries was observed. II.Retinal capillaries of normal people and primary open-angle glaucomatous patients aged over 18 years were examined by using 37 unit high distinguishable retinal imaging system. The images were taken 1 degree below the foveola and the data were statistically tested.
I. Five mildly damaged eyes, three moderately damaged eyes and three severely damaged eyes were evaluated. Dense and intact perifoveal vascular rings were observed in all the eyes. The vessels` area percentages, as well as area, perimeter and diameter of the foveal avascular zones, were measured, and no statistically differences were found among different groups (P values were 0.269, 0.500, 0.951, and 0.555 separately). The ultra structures of the normal capillaries showed regular tubes and intact basement membranes, while lipoid substances in capillary tubes, swollen mitochondria in endothelial cell bodies, and uneven basement membranes were found in the high intraocular pressure-damaged eyes. II.Five clear images in normal group and 4 in glaucomatous group were evaluated. The mean diameter of the capillaries in normal group was 5.39µm, and that in glaucomatous group was 3.91µm. The difference between both groups was statistically significant (P=0.047). No obvious differences in the total length and the number of branches were found between the two groups.
Compared with normal eyes, swollen mitochondria in endothelial cells and lipoid substances in capillary tubes were present in high intraocular pressure model. Besides, the macular capillaries in the primary open angle glaucomatous patients became thinner than normal controls. Both might suggest that high intraocular pressure could damage the capillary endothelial cells and cause vascular automatic dysregulation.
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