The vascular responses of the eye

Abstract

Injury of the iris by stroking or the suspension of the intraocular circulation produces a typical triple response similar in its main characteristics to that occurring in the skin or conjunctiva. Such a response appears to be absent in other internal organs. It is composed of: (1) a local dilatation of the minute vessels; (2) an increased permeability of the capillary walls; (3) a widespread dilatation of the arterioles of the uyeal tract. (1) and (2) are independent of the activity of the sensory nerves and appear to be due to the local effects of the liberation of an H-substance in the tissues; (3) is directly dependent upon the adequate functioning of the 5th nerve and appears to be dependent upon an axon reflex. These responses produce a rise in the intra-ocular pressure and may form a factor in the etiology of certain cases of glaucoma; they may also form a basis for some of the manifestations of herpes in the inner eye.