NTN1 and familial isolated deficiency of vitamin E: Since hyperglycemia is considered a primary cause of diabetic VED, we examined levels of netrin-1 and its downstream pathway in BAECs exposed to normal glucose (NG, 5.5 mmol/L), high glucose (HG, 25 mmol/L) or mannitol (5.5 mmol/L D-Glucose + 19.5 mmol/L mannitol) media for 48 hrs.