Abstract
PurposeVitreous vitamin C, as an anti-oxidant, is responsible for regulating oxygen tension and oxidative stress in the eye. Oxidative stress and retinal ischemia are implicated in the development of proliferative diabetic retinopathy (PDR). In this study, we aimed to determine whether vitreous level of vitamin C is compromised in patients with PDR and to investigate the association of diabetic macular ischemia and vitamin C.MethodsThis prospective study enrolled forty patients who underwent pars plana vitrectomy for the treatment of PDR (PDR group, n = 20) and idiopathic epiretinal membrane (control group, n = 20). Serum, aqueous humor, and the vitreous were collected for the analysis of vitamin C level by HPLC. Diabetic macular ischemia (DMI) in PDR group was evaluated with fluorescein angiography (FA).ResultsPDR patients (60.4 ± 2.1 y) were younger than non-diabetic control patients (67.4 ± 1.2 y). Serum, aqueous, and vitreous levels of vitamin C in PDR were 38.7%, 22.5%, and 11.1% of non-diabetic control group, respectively. All PDR patients had DMI (grade 1: 25%, grade 2: 30%, grade 3: 30%, grade 4: 15%). DMI grade was inversely correlated with the level of vitreous vitamin C (r = -0.546, P = 0.019), not with HbA1C, serum, or aqueous vitamin C level. In addition, the level of vitreous vitamin C (4.5 ± 2.6 μg/ml) in high DMI group (Gr 3 &4) was lower than that (31.0 ± 9.1 μg/ml) in low DMI group (Gr 1&2) (P = 0.015).ConclusionsVitreous level of vitamin C in PDR patients showed a tenfold decrease, which was associated with the degree of macular ischemia. This suggests that vitreous vitamin C depletion may cause macula ischemia in PDR patients.
Highlights
Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus and is a leading cause of blindness in the working population worldwide [1]
Vitreous level of vitamin C in proliferative diabetic retinopathy (PDR) patients showed a tenfold decrease, which was associated with the degree of macular ischemia
This suggests that vitreous vitamin C depletion may cause macula ischemia in PDR patients
Summary
Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus and is a leading cause of blindness in the working population worldwide [1]. Both diabetic macular edema and proliferative diabetic retinopathy (PDR) cause severe visual impairment [2]. Hyperglycemia and retinal ischemia are the main causes of macular edema and neovascularization in PDR. According to the Early Treatment of Diabetic Retinopathy Study (ETDRS) report 11, DMI assessed by fluorescein angiography (FA), in a clinical setting, is correlated with poor visual prognosis [3]. DMI is associated with PDR [4]
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