Topical instillations or parabulbar injections of corticosteroids produce an increase of insoluble polymerized acid mucopolysaccharides. These glycosaminoglycans close the intratrabecular meshes by increasing the thickness of the trabeculae. Perfusion with hyaluronidase, which depolymerizes the mucopolysaccharides, diminishes the diameter of the trabeculae, the more so that after the suppression of the corticosteroid treatment the lysosomal membranes become more permeable for the acid hydrolases.