Catecholamines in aqueous humour of glaucoma patients

Aqueous humour catecholamine concentrations were assayed in open angle glaucoma, and cataract patients during surgery, under general anaesthesia. Plasma catecholamines were measured at the same time. Aqueous humour noradrenaline is apparently reduced by pretreatment with adrenaline, timolol and pilocarpine. (Noradrenaline concentrations were 0.599 +/- 0.239 ng/ml in glaucoma, and 0.970 +/- 0.445 ng/ml in cataract patients.) Dopamine was found in two of six cataract patients (0.123 and 0.318 ng/ml), and in all the glaucoma group (0.221 +/- 0.170 ng/ml). Plasma noradrenaline concentration was probably increased in glaucoma, when compared to the cataract patients. These results confirm our findings in the non-human primate, and suggest that adrenaline may act, at least in part, by causing denervation or inhibition of noradrenaline release in the anterior segment of the eye, and probably by release of dopamine into the aqueous humour. The unexplained and new finding of dopamine in the aqueous humour may have some bearing on the action of dopaminergic drugs for the treatment of glaucoma. Future treatment of ocular hypertension may rely more on sympathetic denervation than on conventional adrenergic therapy.