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E. Vecino, A. Bayon, M. Hernandez, R. M. Almela, A. Cozzi, D. Rodriguez; Molecular and Funtional Changes in the Eye and Retina From Control to Advanced Experimental Glaucoma: A Novel Minipig Model. Invest. Ophthalmol. Vis. Sci. 2007;48(13):205.
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To identify the possible correlation between molecular and functional changes in the eye and retina during the evolution of the intraocular pressure (IOP) elevation.
Right and left eyes of 8 adult minipigs were evaluated at the beginning of the study with different methods: tonometry, retinography, angiography, pachymetry and electroretinography. Left eyes were operated in order to increase the IOP by cauterizing 3 episcleral veins, wile the right eye was used as control. Measurement of IOP was performed weekly. Eighteen months after episcleral vein occlusion, eyes were evaluated again by the same methods that at the beginning of the study. Then, the animals were euthanatized, the retinas fixed and processed for immunohistochemistry by using specific molecular markers for photoreceptors (rod and cone opsins), inner retina (calcium binding proteins and neurotrophins) and glial cells (GFAP and vimentin) in order to study the possible changes in the retina after the elevation of the IOP.
Elevation of IOP after cauterization of the episcleral veins was apparent by the same day after operation and remained elevated during the experimental period in some animals (n= 5). No significative changes were found in the cornea thickness. The elevated IOP led a slight decrease in the vasculature of the venous ring. The electroretinographic analysis showed a significative decrease of the a and b waves amplitude (p<0.05). Moreover we have found a significative decrease in the number of RGCs, an activation of astrocytes and changes in the expression and connectivity of the outer retinal layers.
We have correlated molecular, vascular and functional changes in the retina after long periods of elevation of IOP. Retinal changes in the minipig retina by episcleral vein occlusion, resemble those reported in human glaucoma.
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