CIRCULATION IN THE IRIS AND CILIARY PROCESSES: POSSIBLE RECIPROCAL RELATIONSHIP
1965; BMJ; Volume: 49; Issue: 1 Linguagem: Inglês
10.1136/bjo.49.1.6
ISSN1468-2079
Autores ResumoA RECENT observation in experimental animals suggests that there may be a reci- procal relationship between the arterial blood flow in the ciliary processes and the iris.While this process has not been conclusively proven, it appears of sufficient interest to warrant mention.In mammals, the ciliary processes and iris derive their arterial supply solely from the major arterial circle of the iris t.This circle is formed by anastomosis of the terminal branches of the medial and lateral long posterior ciliary arteries and anterior ciliary arteries.Besides the arteries subserving the ciliary processes and the iris, the major circle also provides some of the recurrent branches to the choroid though these tend to be small.There is little or no evidence to suggest a collateral arterial blood supply for the iris and ciliary processes by any other route.Thus the two tissues comprising a portion of the anterior uvea share a common vascular supply.It is difficult at present to ascertain how much blood either tissue takes from the major circle.Grossly (in rabbits, rats, and in guinea-pigs), it appears that ciliary processes have slightly wider arterial channels than the iris.However, the arterioles of the ciliary processes tend to bend obliquely backwards, whereas the vessels of the iris generally come straight forward off the circle, possibly favouring flow towards the iris.Not infrequently, a branch from the major circle supplies both iris and ciliary processes.Variations in size of the pupil with consequent change in the path of the iridic vessels would appear to modify blood flow to this tissue and perhaps secondarily affect flow to the ciliary processes.The present report stems from the following observations:In an attempt to outline the intra-ocular vascular tree of rats, Indian ink was injected into the still-beating heart of the terminally anaesthetized animal.In several instances the intra-ocular vessels, with the exception of those in the ciliary processes, filled completely, creating a rather striking picture (Fig. 1, opposite).In other instances, only a portion of the ciliary processes was filled with Indian ink, whereas blood could be seen in the uninjected portion of the process.It was noted, however, that when atropine had been instilled into the eye before injection the ciliary processes filled adequately with ink, and that the iridic vessels occasionally appeared less well filled (Fig. 2, opposite).As a consequence of the above observations, the following experiment was performed:Pilocarpine drops 4 per cent.were instilled into the right conjunctival sac and atropine
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