Reperfusion damage

Reperfusion injury refers to tissue damage caused by the blood supply returning to the tissue after a period of ischemia. The absence of oxygen and nutrients from the blood creates a condition in which the restoration of the blood circulation results in inflammation and oxidative damage through the induction of oxidative stress, rather than restoration of normal function.

Reperfusion injury is best known from organ transplantation. The transplanted organ is not perfused for minutes or hours until it gets blood supply from the recipient. Experimentally, reperfusion injury to the retina is caused when retinal circulation is reversibly blocked due to a marked increase in intraocular pressure (IOP). This type of reperfusion damage is clearly different from what happens in the human eye with primary open-angle glaucoma (POAG). In people with POAG, the oxygen tension in the tissue falls temporarily; this drop is very mild but recurs over years. Such a drop in oxygen leads to what is known as preconditioning, which makes the cell more resistant to a further decrease in oxygen. If the oxygen amount exceeds a certain limit, the result is reperfusion damage. If this amount is even larger or lasts longer, a tissue infarction occurs (Figure 7.1).