Angiography and mfERG show that blood supply to the pig retina may be both ipsilateral and contralateral.

Purpose: We recently presented a transfemoral endovascular coiling technique for inducing experimental retinal ischemia in pigs. Substantial variation was seen in the degree of ischemia. It was hypothesized that the blood supply to the retina may originate from both the ipsi- and contralateral ophthalmic arteries, and that there may be an interconnecting artery between the eyes. Methods: The external carotid system of ten pigs was catheterized using a fluoroscopy- monitored, transfemoral, endovascular approach. Vascular occlusion was achieved in the ophthalmic artery using coils. The effect of occlusion was examined using angiography and multifocal electroretinography (mfERG). Results: During angiography of the ophthalmic artery on one side, contrast filling was seen in the retinas on both sides, suggesting that the ophthalmic artery on one side may supply both retinas. A blood vessel connecting the eyes was visualized. mfERG recordings showed that the use of coiling to occlude the ophthalmic artery had greater ischemic effects in eyes that depended mainly on the ipsilateral ophthalmic artery for blood supply and smaller ischemic effect in retinas that received blood from both the ipsilateral and contralateral ophthalmic artery via the interconnecting vessel. Conclusions: The blood supply to the retina may originate from both the ipsi- and contralateral ophthalmic artery in the pig. There is an interindividual variability in the ischemic effect of occlusion depending on the architecture of the vasculature. These findings may be important in the development of new animal models of experimental retinal ischemia, since arterial occlusion in one eye may affect the blood supply to the contralateral eye.