Formation Of The Aqueous Humor

Abstract

1. Glaucoma is a worldwide disease affecting approximately 1-2% of the population aged over 35 years in industrial countries and is a major cause of blindness. 2. Glaucoma is usually associated with an increased intraocular pressure reflecting an imbalance between the rate of production of fluid (the aqueous humor) by the ciliary epithelial cells and its drainage from the eye. Therefore, it is important to understand how this secretion is produced. This requires a knowledge of ciliary epithelial cell composition, which has, in the past, proved difficult to obtain in mammalian preparations. 3. We have recently used the technique of electron-probe X-ray microanalysis 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.

Protective effect of free-radical scavengers on corneal endothelial damage in phacoemulsification

“…35,39,54 These levels of ascorbic acid are higher in ocular tissue than other water-soluble antioxidants. The free-radical scavenging process by ascorbate in the eye was demonstrated by Rose et al 23 Several studies provide evidence that ascorbic acid offers significant antioxidative protection to the eye by scavenging reactive oxygen species 35,36,39 and may be an important factor in endothelial cell healing, migration, and regeneration.…”

Fluid transport phenomena in ocular epithelia

“…Following this, several investigators were able to isolate the ciliary body epithelia of toad, shark, rabbit, and bovine with which active transport mechanisms for Cl -, Na + and HCO 3 -were described . Complementing this work, other investigators have used the isolated tissue to look for transporters with intracellular electrodes (Chu and Green, 1990;Wiederholt and Zadunaisky, 1986), fluorescent probes (Butler et al, 1994;Wolosin et al, 1991), electron probe (Bowler et al, 1996;Macknight et al, 2000), and patch clamp techniques (Chen and Sears, 1997;Chen et al, 1998;Edelman et al,1995;Wang et al, 2000), or have used cultured CE cells to look for channels using microelectrodes (Helbig et al, 1989c) or patch-clamping CoCa-Prados et al,1995,1996Yantorno et al, 1992), and for transporters using radioisotopes (Helbig et al 1988(Helbig et al ,1989a(Helbig et al ,1989b, or fluorescent techniques (Tao et al, 1998;Hou et al, 1998Hou et al, ,2000. As a result of this wealth of information, several models have been proposed to explain aqueous humor production by the ciliary epithelium (Civan, 1997;Civan and Macknight, 2004;Jacob and Civan, 1996).…”

Flufenamic acid enhances current through maxi-K channels in the trabecular meshwork of the eye

“…1 Despite extensive research for neuroprotective agents that might prevent degeneration of the ganglion cells directly, 2 the major treatment option continues to revolve around normalization of intraocular pressure, either by reducing inflow, or increasing outflow of aqueous humor, as elevated levels of intraocular pressure aggravate the course of the disease. 3 The major part of outflow resistance is determined by the trabecular meshwork, a filter-like structure between the anterior chamber and Schlemm's canal. 4,5 This structure contains smooth muscle-like myofibroblasts and is not only passively distended by the ciliary muscle, but has been shown to contract and relax actively.…”