UHM 2012, Vol. 39, NO. 5:943-953
The retina has a dual blood supply, with the retinal circulation supplying the inner layers and
the choroidal circulation supplying the outer layers. In CRAO. vision loss results from cell death
in the inner retinal layers despite relative sparing of the outer layers.
O2 from the choroidal circulation may diffuse in adequate quantity to the inner layers of the retina to maintain retinal function and restore vision.
In some patients this can be achieved with normobaric hyperopia, in others, HBO2 may be required.
In experimental models of complete CRAO, the ischemic time window before permanent retinal damage occurs is just over 90 mins; in the clinical setting where occlusion may be incomplete, return of vision may be achieved even after delays of 8 to 24 hours.
NRM(high FiO2) -＞vision not restored->HBO2-＞until the obstructed retinal artery recanalizes, which typically occurs within 72 hours.
臨床處置：當視力突然低於20／200
1.使用血管擴張劑並用眼底鏡觀察。
2.詢問是否產生閃光或有漂浮物，視力喪失，痛，最近創傷／手術史或年齡低於40歲，建議可能其它診斷（如：視網膜剝離或玻璃體出血）。
3.會診眼科醫師。
4.立刻給予O2。
5.測眼壓，升高時給予治療。或予以前腔窒穿刺放液。
6.檢查CBC（有無血小板病變或感染），ESR（檢查有無動脈炎），高凝血物質(fibrinogen, PT/PTT, anti phospholipid antibody), lipid panel, EKG, carotid ultrasound.
7.HBO.
8.若為血管發炎性的CRAO，可用iv的steroid.
氧氣調節：
1.立即給予高濃度氧氣（如：NRM）
2.若對氧有反應，每小時吸15分鐘氧氣，45分鐘空氣。
3.若對氧無反應，給HBO 2ATA, 90分鐘。
4.若無反應，HBO 改為2.4 ATA, 90分鐘。
5.若無反應，HBO 改為2.8 ATA, 90分鐘。
1980 Augsberger and Magargal硏究報告指出：成功組治療延遲時間為21.1小時，失敗組平均為58.6小時。
本篇回顧28篇，均為retrospective studies，樣本數共476人，成功人數為主306人，成功率為65%，但不是meta analysis, 療程也多不一致。
此篇於2012進行midline search 4篇樣本數小的RCT，均無臨床正向效果，因此僅能儘量可能有效的治療，包括HBO2。
