Several enzymes are involved in the production of aqueous humour. Energy for active transport of aqueous humour from ciliary endothelial cells mainly stems from converting adenosine triphosphate to adenosine diphosphate with the sodium-potassium enzyme (Na-K-ATPase). This enzyme can be inhibited by compounds such as cardiac glycosides, acetazolamide and dinitrophenol.⁸

Carbonic anhydrase provides bicarbonate (dependent on pH), while sodium and chloride ions, ascorbic acid and amino acids are also actively transported across the epithelium. The resulting osmotic gradient promotes the movement of other plasma components.⁸

Damage to the optic nerve is usually due to compression which blocks the flow of cytoplasm along the optic nerve fibre axons depriving it of oxygen and other nutrients.⁸