Formation of the aqueous humor

1. Glaucoma is a worldwide disease affecting approximately 1-2% of the popu lation aged over 35 years in industrial countries and is a major cause of b lindness. 2. Glaucoma is usually associated with an increased intraocular pressure re flecting an imbalance between the rate of production of fluid (the aqueous humor) by the ciliary epithelial cells and its drainage from the eye. There fore, it is important to understand how this secretion is produced. This re quires a knowledge of ciliary epithelial cell composition, which has, in th e past, proved difficult to obtain in mammalian preparations. 3. We have recently used the technique of electron-probe X-ray microanalysi s to determine this composition under a variety of in vitro conditions. 4. Our results have led to a new model for this secretion that emphasizes the potential secretory role of the Na+/K+/2Cl(-) cotransporter.