Amino-acid levels in subretinal and vitreous fluid of patients with retinal detachment

Abstract

Purpose: To compare the concentration of amino acids in subretinal and vitreous fluid of patients with primary rhegmatogenous retinal detachment to that of control vitreous. Methods: This prospective, observational study measured amino-acid levels in subretinal fluid of patients undergoing scleral buckle placement (n = 20) and vitreous fluid in patients undergoing pars plana vitrectomy (n = 5) for primary retinal detachment. Vitreous fluid from patients undergoing vitrectomy for macular hole (n = 7) or epiretinal membrane (n = 3) served as a control. Subretinal fluid and control vitreous were analysed using high-pressure liquid chromatography. Retinal detachment vitreous was analysed using capillary electrophoresis-laser-induced fluorescence. Results: Mean levels of glutamate (27.0 ± 1.7 μM), aspartate (4.1 ± 4.0 μM), and glycine (44.1 ± 31.0 μM) in subretinal fluid and glutamate (13.4 ± 11.9 μM) in the vitreous were significantly elevated in retinal detachment compared to control vitreous. A significant, positive association was observed between levels of aspartate and glutamate in subretinal fluid (Spearman's correlation coefficient: 0.74, P < 0.01). Mean arginine levels did not differ significantly between subretinal fluid and control vitreous. Levels of alanine, tyrosine, valine, isoleucine, leucine, and phenylalanine were significantly lower in subretinal fluid compared to control vitreous (all P < 0.01). Conclusions: Glutamate levels in subretinal fluid and vitreous of patients with primary retinal detachment is significantly elevated in comparison to control vitreous. This finding lends further support to the hypothesis that elevated glutamate levels may result from ischaemia of the outer retina secondary to retinal detachment.