title: Vitamin C levels in human tears.
abstract: Human tears, collected using the Schirmer strip method, were analyzed by high-performance liquid chromatography for vitamin C (ascorbic acid). In "basal" tears, the levels of ascorbic acid ranged from 3.9 to 23 mg/dL (220 to 1310 mumol/L); lower values correlated with higher tear flow rates. In reflex tears, induced by brief ammonia inhalation, the ascorbic acid level fell dramatically and appeared to reach a minimum level around 2 mg/dL (110 mumol/L). Even the low level in reflex tears, however, was consistently higher than plasma levels. Ascorbic acid in tears has a potential anti-inflammatory role.
mesh_terms: D000328:Adult; D064753:Ammonium Hydroxide; D001205:Ascorbic Acid / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005260:Female; D006801:Humans; D006878:Hydroxides; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012018:Reflex / Q000187:drug effects; D013666:Tears / Q000032:analysis* / Q000187:drug effects
chemical_list: D006878:Hydroxides; D064753:Ammonium Hydroxide; D001205:Ascorbic Acid