[Free radicals]

Free radicals are continuously threatening living organs. Firstly generated by endogenic pathway during normal and vital metabolic reactions, they can be also produced by environmental factors: atmospheric pollution, radiations... An energetic source ensures the initiation of free radicals reaction. Its expanding is strengthened by oxygen (bi-radical form) and transition metals (chiefly iron). Eyes are very sensitive organs to the deleterious action from the oxygen active species. Protection systems against free radicals action are necessary in living cells. A part the pathologic or ageing conditions, oxygen toxicity doesn't; in fact, neutralised by protection systems coming from enzymes (endogenic way) and food contribution: vitamins, carotenoids, flavonoids... (exogenic way).