Background: The objective of this clinical study is to examine the association between D-serine and diabetic retinopathy (DR).
Design: Retrospective, case-control study was performed in the affiliated Eye Hospital of Wenzhou Medical University.
Participants: This study included 25 patients with proliferative diabetic retinopathy (PDR), and 25 sex- and age-matched control subjects, i.e. patients with idiopathic macular hole and idiopathic epiretinal membrane.
Methods: Clinical diagnoses were made by the senior ophthalmologists in the Eye Hospital; the aqueous and vitreous humour specimens were collected from these patients undergoing pars plana vitrectomy for treating complications.
Main outcome measures: The aqueous and vitreous levels of D-serine and glutamate were measured with reverse-phase high-performance liquid chromatography (HPLC); the contents of haemoglobin in the blood and in the vitreous specimens from PDR were measured with spectrophotometry to correct possible introduction of amino acids from PDR haemorrhage.
Results: The concentrations of D-serine in the aqueous or vitreous humour were significantly higher in patients with PDR compared with control subjects. The vitreous concentrations of D-serine in PDR were 25.55 ± 0.63 μmol/L compared with control subjects at 22.76 ± 0.36 μmol/L (P = 0.002); the levels of D-serine in the aqueous humour from patients with PDR were 29.08 ± 1.31 μmol/L compared with control subjects at 24.22 ± 0.65 μmol/L (P = 0.006). Correction from possible introduction of D-serine from the vitreous haemorrhage in PDR did not significantly alter the findings.
Conclusions: Increased D-serine in the aqueous and vitreous humour was found in patients with PDR compared with control subjects.
Keywords: diabetic retinopathy; excitotoxicity; glutamate; retinal neuronal death; serine racemase.
© 2014 Royal Australian and New Zealand College of Ophthalmologists.