Catecholamine concentrations in tears

Lacrimal fluid from 17 healthy volunteers was analysed for catecholamines using a radioenzymatic assay. Significant concentrations of norepinephrine (mean = 4.4 nmol l-1) and epinephrine (mean = 3.7 nmol l-1) were detected in some of the subjects. Dopamine was not detected in the tears of any of the subjects. The possible significance of catecholamines in tears in relation to corneal physiology and intraocular pressure is discussed.