Retinal function was assessed by electroretinogram in 32 neonates randomly assigned to formulas of different omega-3 fatty acid content and in 10 infants fed human milk.

All neonates had a birth weight of 1000-1500 g and were fed study diets from d 10 to 45 or discharge. Group A received formula containing predominantly 18:2 omega-6. Group B received a balanced mix of 18:2 omega-6 and 18:3 omega-3. Group C was given a formula containing both essential fatty acids and supplemented with marine oil to provide 22:6 omega-3 content similar to that of human milk.

The fatty acid composition of plasma and red blood cell (RBC) lipids were similar for all groups on entry but marked diet-induced differences were found after feeding the study diets. Group C was comparable to the human milk-fed group, but group A had lower 22:6 omega-3 and omega-3 long-chain polyunsaturated fatty acids (LCPUFA) in plasma and RBC membranes.

Cone function was not affected by dietary essential fatty acids. Rod electroretinogram thresholds were significantly higher for group A relative to the human milk-fed group and group C and significantly correlated with RBC omega-3 LCPUFA (r = -0.63, p less than 0.0001); 44% of the variance could be explained by RBC and plasma omega-3 LCPUFA content.

Rod electroretinogram amplitude was significantly lower for group A relative to the human milkfed group and group C and related to plasma 22:6 w-3 (r =0.55) and total w-3 LCPUFA (r =0.58) (both p < 0.0001); 42% of the variance was explained by plasma w3 LCPUFA, the ratio of w-6/w-3 LCPUFA in RBC, and gestational age at birth.

Our results support an essential role for w-3 fatty acids in retinal development.