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Raul Velez-Montoya, Jeffrey Olson; Vitreous oxygenation bio-implant for central retina artery occlusion. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5798.
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Central retinal artery occlusion (CRAO) is a rare but devastating eye emergency, characterized by a sudden stop of the oxygen supply to the retina due to a decrease in retinal perfusion. The damage to the ocular tissue due to severe hypoxemia may be reversible if the oxygen supply is restored during the first 90 minutes to up to the first 8 to 24 hours if the occlusion is not total. After this time, the damage is rendered irreversible, even though the blood supply is restored. To try to solve this problem, a membrane encapsulated bio-implant was designed, aimed to deliver high concentration of oxygen to the retinal tissue during the window period in where damage can be prevented. The objective of this study is to assess the feasibility and oxygen delivery capabilities of the prototypes as well as to assess its effects on retinal tissue in an animal model of CRAO.
Sixteen animals (rabbits) were divided into three groups (control 4, sham 5 and active 7). A CRAO were induced by increasing the intraocular pressure up to 90mmHg through the insertion of a needle in the anterior chamber attached to a water column. The occlusion was sustained for 90 minutes. The vitreous oxygen content was measured before the occlusion and 1 hour after the event. During the recovery time the sham group received an active implant while the active group received the oxycell implant. There was no implant for the control group. An electroretinogram (ERG) was done in all animals at baseline and at 15 days of follow up.
There was no difference in vitreous oxygenation at baseline. There was a statistical significant (p<0.01) increase in the vitreous oxygenation among the rabbits on the active group, 1 hour after the CRAO. However the oxygen levels decreased fast, reaching the same as in the control and sham group at day 3 of follow-up. The ERG showed no improvement on retinal function of the active group.
The membrane encapsulated bio-implant seems to be a viable option for increasing vitreous oxygenation during a CRAO. Further studies are needed in order to understand the best way to use this capability in order to prevent retinal damage.
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