Morphological and morphometric changes in rat optic nerve microvessels in a glaucoma experimental model

Abstract

AimTo study the morphological and morphometric changes produced in the capillaries of the optic nerve (ON) head and initial portion after the experimental increase in intraocular pressure (IOP). Material and methodsWistar rats underwent cauterization of three episcleral veins, which produced an immediate increase in the IOP, and was maintained for 3 months. Sagittal sections of the eyeball were studied with immunohistochemical techniques, using a primary antibody to GLUT-1. The GLUT-1 positive capillaries were counted, and measurements were made of the area, perimeter and mean diameter. ResultsMicroscopic examination of sections of the ON of control rats revealed a lower density and larger caliber of capillaries in the prelaminar region as compared with the other regions of the OP (p<.05). Comparison between the control and the experimental groups showed a reduction in capillary density (except in the prelaminar region) and a smaller size in all the areas of the OP studied, but less evident in the initial portion (p<.05). ConclusionsThe increase in IOP was associated with significant qualitative and quantitative changes in the capillaries of the laminar and poslaminar regions of the OP head. These changes appear to return toward parameters compatible with normality in the initial portion of the OP, an area where the vascular collapse was less evident. These findings might explain the significant reduction in ocular blood flow seen in patients with primary open-angle glaucoma.