THE HUMAN eye is a unit consisting of an image-producing apparatus—cornea, aqueous humor, lens, and vitreous body—and an image-receiving apparatus, the retina. In order to function normally, this unit has to be properly protected, nourished, and kept under optimal conditions. Among these, nutritional and oxygen supply, adequate temperature and hydrogen ion concentration, elimination of waste products, and preservation of a normal intraocular pressure are of paramount importance.
The maintenance of normal intraocular pressure depends on the elasticity and rigidity of the ocular coats, i. e., sclera and cornea, and on the contents of the eyeball. These are composed of the intraocular fluids and tissues and the quantity of blood filling the vessels of the intraocular tissues, particularly the uvea.
All over the body, fluid may leave or enter capillaries according to the relative values of tissue pressure and intravascular pressure and of osmotic and colloidal osmotic pressure which prevail
ASCHER KW. AQUEOUS VEINSTheir Status Eleven Years After Their Detection. AMA Arch Ophthalmol. 1953;49(4):438-451. doi:10.1001/archopht.1953.00920020448009