Purpose: Diabetes results in an insulin related disorder of lipid metabolism that reduces production of long-chain polyunsaturated fatty acids (PUFA; e.g. docosahexanoic acid, DHA). This study considers the role that this lipid change has on retinal function.

Methods: Rats (n=56) were fed diets either balanced (n=32) in PUFA or deficient in omega-3 (n=24) from conception. Half were assigned to control (n=28) or streptozotocin (STZ: n=28) treatment at 7 weeks of age. Key metabolic indices were assayed at 19 weeks and retinal function was determined using the electroretinogram (ERG) at 20 weeks. Retinal anatomy and lipid assays of 20-week animals were used to identify structural changes and tissue PUFA content.

Results: The systemic indices of diabetics were not affected by diet. Lipid composition of retinal membranes reflected the dietary manipulation and diabetes amplified some fatty acid changes consistent with a reduced desaturase activity. Diabetes produced significant reduction in rod function (-33%) only in the absence of fish oil, whereas cone responses (-46%) and inner retinal oscillatory potentials (-47%) showed either no diet effect or a partial diet effect with a significant diabetes effect. Anatomical analysis revealed no disorder in retinal neurons although changes in Müller glia were noted in diabetes regardless of diet.

Conclusions: A diet balanced in long chain PUFA will modify retinal lipid membranes in diabetes and prevent rod dysfunction. Dietary modification was not found in the cone or glial response but a partial improvement was evident in OPs most likely secondary to the larger photoreceptor output.