Nitric oxide and oxidative stress is associated with severity of diabetic retinopathy and retinal structural alterations

BackgroundThe aim of the study was to determine plasma nitric oxide (NO) and lipid peroxide (LPO) levels in diabetic retinopathy and its association with severity of disease. DesignProspective observational study. ParticipantsA total of 60 consecutive cases and 20 healthy controls were included. MethodsSeverity of retinopathy was graded according to early treatment diabetic retinopathy study (ETDRS) classification. Photoreceptor inner segment ellipsoid band (ISel) disruption and retinal pigment epithelium (RPE) alteration were graded using spectral domain optical coherence tomography. Data were statistically analyzed. Main Outcome MeasuresPlasma thiobarbituric acid reactive substances, NO assay and reduced glutathione (GSH) were measured using standard protocol. ResultsIncreased severity of diabetic retinopathy was significantly associated with increase in plasma levels of LPO (P<0.05), NO (P<0.001) and decrease in plasma levels of GSH (P<0.0001), ISel disruption (P<0.001) and RPE topographic alteration (P<0.01). ConclusionIncreased plasma NO levels are associated with increased severity of diabetic retinopathy. For the first time, it has been demonstrated that increased plasma LPO, NO and decreased GSH levels are associated with in vivo structural changes in inner segment ellipsoid and RPE.