Needs in omega 3 and ocular pathologies

Life expectancy at birth has regularly increased decade after decade, especially since the beginning of the 20th century: 15 years have been gained over the past 50 years. Changes in living and dietary habits during this time period have been associated with the development of various pathologies which represent a growing socioeconomic burden. Among age-related disorders, ocular diseases are the second most prevalent ones after 65 years. Age-related Macular Degeneration (AMD) is the leading cause of visual impairment after the age of 50 years. Age is the prominent risk factor for AMD and is accompanied with both endogenous (including genetics) and environmental factors, such as smoking habits and dietary factors (diet rich in cholesterol and saturated fatty acids). AMD is characterized by the loss of cells at the most central area of the retina, called macula. The neural retina is a highly structured neurosensory tissue that is responsible for the transduction pathway. The transduction pathway is initiated in photoreceptors where the light stimulus is coded into an electrical signal. This signal is transmitted to neighboured neurons and transferred to the brain via the optic nerve. The retinal pigment epithelium (RPE) is the cellular and metabolic interface between the neural retina and choriocapillaris through Bruch’s membrane. The close association between RPE and photoreceptors is one of the factors that promote the efficacy of RPE to, in the one hand, provide nutrients and oxygen to photoreceptors and, in the other hand, eliminate the metabolic debris originating from shedding of the outer segments. Epidemiological data suggest that dietary habits privileging the consumption of omega- 3 long chain polyunsaturated fatty acids participate to prevent from the development of AMD (Sangiovanni et al., 2009). The mechanisms underlying the effects of omega-3 fatty acids remain unclear until now. The purpose of the present paper is to give a review on the role, metabolism and effects of omega 3 fatty acids in the retina.