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Hakan Moren, Bodil Gesslein, Per Undren, Sten Andreasson, Malin Malmsjö; Interocular Vascular Communication Through Collateral Vessels In An Experimental Pig Model. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6856.
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The authors recently presented an endovascular coiling model of retinal ischemia. In order to elaborate this model, the aim of this study was to examine if there is collateral blood supply with direct communication between the right and left eye. Also, the aim was to examine if the extent of ischemia following vascular occlusion is dependent on this collateral blood supply.
The external carotid system of 8 pigs (mean weight 70kg) was catheterized using a fluoroscopy monitored, transfemoral, endovascular approach. Vascular occlusion was performed in the ophthalmic artery using coils. Retinal function was evaluated after occlusion using multifocal electroretinography (mfERG).
Unilateral angiograms of the ophthalmic artery showed bilateral retinal contrast filling almost simultaneously. There were angiographic signs of net collateral flow from the right to the left eye or vice versa. Occlusion of the ophthalmic artery in eyes where the net collateral flow originated resulted in attenuated mfERG b-wave amplitudes on day 1 in both eyes indicating retinal ischemia. By contrast, occlusion in eyes with both direct and collateral blood supply resulted in less attenuated amplitudes in both eyes indicating less ischemia.
The present study shows evidence of direct vascular communication through collateral blood vessels between the two eyes. This has not been shown in pigs before. An interocular collateral net flow could be present in either direction. The degree of ischemia following occlusion of the ophthalmic artery seems to be influenced by whether the occluded eye has only direct or also additional collateral supply. This collateral blood circulation may have clinical importance, i.e. to modulate the level of ischemic damage to the retina in the event of vascular occlusion. It may also be of importance to further development of experimental models of retinal ischemia.
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