The effect of unilateral common carotid occlusion and of acute unilateral preganglionic cervical sympathotomy on the anions of the aqueous humour

Abstract

The demonstration (Linner, 1952) that the relative differences in blood flow through the two eyes of the rabbit after unilateral ligation of the common carotid artery and after acute unilateral preganglionic cervical sympathotomy are paralleled by changes in the concentration of ascorbate in the aqueous humours implies that these operations have no effect on the rate of flow of aqueous humour. On the other hand, the work of Batrany (1947) and of Davson & Matchett (1951, 1953 indicated that carotid occlusion decreases, and acute sympathotomy increases, the rate of flow of aqueous humour.In an attempt to reconcile these divergent opinions, the concentration of lactate in the aqueous humour after carotid occlusion and after sympathotomy has been studied. This metabolite is present in higher concentration in the aqueous humour than in the plasma owing to its continuous formation by the lens and cornea (Fischer, 1931; Kinsey, 1950Kinsey, , 1953Langham, 1952); a decrease in the rate of renewal of the aqueous humour might therefore be expected to cause an increase in the concentration of lactate and vice versa. The effect of carotid occlusion and of sympathotomy on the lactate of the aqueous humour when the concentration of ascorbate in the plasma was above the saturation level has also been investigated.The concentration of lactate in the anterior aqueous after carotid occlusion and after sympathotomy showed well-defined changes, the nature of which it was difficult to explain on the basis of changes in the rate of flow of aqueous. An alternative explanation supported by a study of the chloride and bicarbonate of the anterior aqueous and the lactate of the posterior aqueous was founded on differences in the rate at which substances exchanged with the plasma across the iris capillary walls. These experiments led to an extension of Linner's original work on ascorbate.