Schlemm's Canal Basal Lamina: A Variable Resistor?

Used aqueous humor leaves the eye through a specially designed filtration tissue known as the trabecular meshwork (TM). The part of this filter with the finest mesh is called the Juxtacanalicular region or simply the JCT. After flowing through the JCT, aqueous humor passes through the cells of the inner wall lining Schlemm’s canal into the venous system. Most clinicians and most researchers believe that the principal site of the resistance to aqueous humor outflow is between the inner aspects of the JCT and the lumen of Schlemm’s canal. Dr. Gong is focusing on the possible role of the basement membrane of Schlemm’s canal in fluid outflow resistance. The basement membrane of Schlemm’s canal exhibits focal discontinuities. She has hypothesized that the normal flow of fluid might “dissolve” little holes in the basement membrane, because the basement membrane becomes more discontinuous in normal eyes when the flow pressure is increased. She is now investigating whether these changes fail to occur in glaucomatous eyes. If this is the case, a new cause for increased flow resistance will have been identified, setting the stage for additional studies to understand the molecular basis for increased resistance.