Aqueous Flow into the Perivascular Space of the Rabbit Ciliary Body

¹ Department of Ophthalmology, College of Medical Sciences, University of Minnesota, Minneapolis, Minn.

Through the use of the histochemical reagent, nitroblue tetrazolium chloride, to label anterior chamber aqueous in the eyes of living albino rabbits, we have been able to trace the pathway of aqueous leaving the anterior chamber angle. Although we could find no evidence that any of the marker had entered the trabecular veins (sometimes called Schlemm's canal) or the trabecular meshwork directly in front of the veins, there was evidence that the aqueous had moved through channels in the ciliary body posterior to the ciliary cleft. The pigmented epithelium of the ciliary body, but not the ciliary processes, was intensely stained with marker, particularly in the areas adjacent to the perivascular aqueous channels. From a detailed study of the distribution of the nitroblue formazan in serial sections of the ciliary body region of eyes injected in vivo with marker 10 minutes before excision and fixation, we have concluded that aqueous leaving the anterior chamber first enters the ciliary cleft from which it flows into the perivascular spaces and perivascular aqueous channels of the ciliary body. The aqueous channels lie adjacent to the pigmented epithelium in the posterior part of the ciliary body and some of them connect with the perivascular space of the suprachoroid. The uptake of stain by the pigmented epithelium of the ciliary body has been interpreted to mean that fluid from this channel system may be resecreted into the posterior chamber.