The long-chain polyunsaturated omega-3 fatty acid docosahexaenoic (22:6n-3) acid (DHA) accumulates in rod outer segment disks and synaptic terminals. It has been thought to play an important role in disordering disk membranes and in providing an adequate environment for conformational rhodopsin changes and in modifying the activity of retinal enzymes. The decrease of DHA content in the retina has been shown to affect visual function in monkey. In rat retina, prolonged light exposure has produced reduction of DHA content in rod outer segments. The authors found that when DHA was administered before ischemia, it diminished pressure-induced retinal damage. The recovery of electroretinographic amplitudes in DHA-pretreated eyes was significantly greater than those in the control eyes after 4 hr of reperfusion. The histopathologic study of control eyes showed cell swelling and cell nuclei pyknosis in the inner nuclear layer after 4 hr of reperfusion and in TUNEL-positive cells in the inner and outer nuclear layers after 24-72 hr of reperfusion. The DHA pre-treated eyes had fewer pyknotic nuclei and vacuolated spaces in the inner nuclear layer and no TUNEL-positive cells for up to 72 hr of reperfusion. The precise role of the polyunsaturated n-3 fatty acid has not been identified in the retina and other tissues.

Our findings showed that DHA probably prevented sensory retina from ischemic-reperfusion cell damage not only by inhibiting the formation of hydroxyl radicals, but also by reducing the non-NMDA responses or the inflammatory responses.