Abstract
Purpose: :
To provide data on the differences in the lipid profile of the neural retina and RPE/choroid in healthy human eyes, and to establish plausible relationships with dietary fat intake, by comparing the lipid profile of the extra orbital fat.
Methods: :
Human eyes were collected from 28 human donors. The neural retina was dissected from the RPE/choroid. In 6 donors, the lacrimal gland and a piece of the extra orbital fat were collected. The lipid profile of the human samples was analyzed into classes. Phospholipids and cholesteryl esters were purified from RPE/choroid. The fatty acid composition of the retina, lipid fractions of RPE/choroid, and lacrimal gland samples was determined by gas chromatography and compared to the extra-orbital fat.
Results: :
Cholesteryl esters accounted for the major difference between the neuroretina and RPE/choroid, 1.7 ± 0.6% and 19.0 ± 3.4% of total lipids, respectively. A positive relationship was found between DHA levels in the neuroretina and cholesteryl esters from RPE/choroid (rPearson=0.78, p=0.01), while the opposite was observed in phospholipids from RPE/choroid (rPearson=-0.71, p=0.03). DHA levels in extra-orbital fat was positively correlated to DHA in lacrimal gland (rPearson=0.74, p=0.02), whereas no significant correlation was observed in the other ocular structures. Linoleic acid in extra-orbital fat and in the ocular structures were positively correlated each others, the greatest relationship was obtained with the lacrimal gland (rPearson=0.99, p<0.0001), followed by cholesteryl esters from RPE/choroid and neuroretina. Other fatty acids that are exclusively of dietary origin, like trans isomers of oleic acid, were detected in extra-orbital fat, lacrimal gland, phospholipids and cholesteryl esters from RPE/choroid. A positive association was found between trans fatty acids levels in extra-orbital fat and lacrimal gland (rPearson=0.91, p=0.0002).
Conclusions: :
Fatty acid composition of the extra-orbital fat was considered as an estimate of the history of the past lipid intake of the subjects. The lacrimal gland was the ocular structure which composition mirrored more closely the fat intake. Apart from DHA, the fatty acid profile of the neuroretina fitted more closely cholesteryl esters from RPE/choroid than phospholipids.
Keywords: lipids • nutritional factors • retina