AQUEOUS HUMOR

 Aqueous humor and its production volum the aqueous humor as a clear watery fluid filling the anterior chamber 0.25 milliliters and posterior chamber 0.06 milliliters of the eyeball functions of aqueous humor are it maintains a proper intraocular pressure it plays an important metabolic role by providing substrates and by removing metabolites from the avascular cornea and lens it maintains optical transparency.

It takes the place of limp that is absent within the eyeball refractive index of aqueous humor as 1.33 6 composition constituents of normal aqueous humor are on water 99.9 and solids 0.1 percent which include proteins colloid content because of blood aqueous barrier the protein content of aqueous humor 5 to 16 milligrams % is much less than that of plasma 6 to 7 GM percent however in inflammation of UV EA irid osek lightest the blood aqueous barrier is broken and the protein content of aqueous has increased plasmoid aqueous amino acid constituent of aqueous humor as about 5 milligrams per kilogram water oxygen is present in aqueous in dissolved state note thus composition of aqueous is similar to plasma except that it has high concentrations of ascorbate pyruvate and lactate and low concentration of protein urea and glucose aqueous humor anterior chamber versus posterior chamber the composition of accuse humor in anterior chamber differs from that of the aqueous humor in posterior chamber because of metabolic interchange the main differences are in posterior chamber aqueous is higher than in the anterior chamber CL concentration in posterior chamber is lower than in the anterior chamber ascorbate concentration of posterior aqueous is slightly higher than that of anterior chamber aqueous production aqueous humor is derived from plasma within the capillary network of ciliary processes.

The normal aqueous production rate is 2.3 micro liters per minute the three mechanisms diffusion ultra filtration and secretion active transport play a part in its production at different levels the steps involved in the process of production are summarized below one ultra filtration first of all by ultra filtration most of the plasma substances pass out from the capillary wall loose connective tissue and pigment epithelium of the ciliary processes thus the plasma filtrate accumulates behind the non pigment epithelium of ciliary processes to secretion the tight junctions between the cells of the non pigment epithelium create part of blood aqueous barrier certain substances are actively transported secreted across this barrier into the posterior chamber the active transport is brought about by na+ k+ activated ATPase pump and carbonic anhydrase enzyme system substances that are actively transported include sodium chlorides potassium ascorbic acid amino acids and bicarbonates 3 diffusion active transport of these substances across the non-pigmented ciliary epithelium results in an osmotic gradient leading to the movement of other plasma constituents into the posterior chamber by ultra filtration and diffusion sodium is primarily responsible for the movement of water into the posterior chamber control of aqueous formation the diurnal variation in intraocular pressure certainly indicates that some endogenous factors do influence the aqueous formation the exact role of such factors as yet to be clearly understood vasopressin and adenyl cyclase have been described to affect aqueous formation by influencing active transport of sodium ultra filtration and diffusion the passive mechanisms of aqueous formation are dependent on the level of blood pressure in the ciliary capillaries the plasma osmotic pressure in the level of intraocular pressure drainage of aqueous humor aqueous humor flows from the posterior chamber into the anterior chamber through the pupil against slight physiologic resistance from the anterior chamber the aqueous is drained out by two roots one trabecular conventional outflow.