Vitreal oxygenation in retinal ischemia reperfusion.
OBJECTIVE
To study the feasibility of anterior vitreal oxygenation for the treatment of acute retinal ischemia.


METHODS
Twenty rabbits were randomized into an oxygenation group, a sham treatment group, and a no treatment group. Baseline electroretinography (ERG) and preretinal oxygen (Po(2)) measurements were obtained 3 to 5 days before surgery. Intraocular pressure was raised to 100 mm Hg for 90 minutes and then normalized. The oxygenation group underwent vitreal oxygenation for 30 minutes using intravitreal electrodes. The sham treatment group received inactive electrodes for 30 minutes while there was no intervention for the no treatment group. Preretinal Po(2) in the posterior vitreous was measured 30 minutes after intervention or 30 minutes after reperfusion (no treatment group) and on postoperative days (d) 3, 6, 9, and 12. On d14, rabbits underwent ERG and were euthanatized.


RESULTS
Mean final (d12) Po(2) was 10.64 ± 0.77 mm Hg for the oxygenation group, 2.14 ± 0.61 mm Hg for the sham group, and 1.98 ± 0.63 mm Hg for the no treatment group. On ERG, scotopic b-wave amplitude was significantly preserved in the oxygenation group compared with the other two groups. Superoxide dismutase assay showed higher activity in the operated eyes than in the nonoperated control eyes in the sham treatment group and no treatment group only. Histopathology showed preservation of retinal architecture and choroidal vasculature in the oxygenation group, whereas the sham-treated and nontreated groups showed retinal thinning and choroidal atrophy.


CONCLUSIONS
In severe total ocular ischemia, anterior vitreal oxygenation supplies enough oxygen to penetrate the retinal thickness, resulting in rescue of the RPE/choriocapillaris that continues to perfuse, hence sparing the retinal tissue from damage.
Doheny Retina Institute, Los Angeles, California, USA.
Walid
W
Abdallah
Hossein
H
Ameri
Ernesto
E
Barron
Gerald J
GJ
Chader
Elias
E
Greenbaum
David R
DR
Hinton
Mark S
MS
Humayun
D000818:Animals; D004596:Electroretinography; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D007429:Intraocular Pressure; D008855:Microscopy, Electron, Scanning; D010100:Oxygen / Q000378:metabolism*; D011817:Rabbits; D015427:Reperfusion Injury / Q000378:metabolism*; D012160:Retina / Q000201:enzymology; D012164:Retinal Diseases / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D014822:Vitreous Body / Q000378:metabolism*
D013482:Superoxide Dismutase; D010100:Oxygen