Evaluation of indoleamine 2,3-dioxygenase expression and kynurenine pathway metabolites levels in serum samples of diabetic retinopathy patients.

Context: Diabetic retinopathy (DR) is the leading cause of acquired blindness. The involvement of indoleamine 2, 3-dioxygenase (IDO) and kynurenines, the products of tryptophan degradation in various pathological conditions was well documented.

Objective: The aim of the present study was to determine the expression of IDO and levels of tryptophan metabolites in serum samples of DR patients.