Changes of structures of anterior chamber angle in rabbit chronic high intraocular pressure model

Abstract

To observe the anterior chamber angle changes occurred in compound Carbomer-induced chronic high intraocular pressure (IOP) model in rabbit eyes. It was an experimental study. Thirty two rabbits were randomly divided into eight groups. Compound Carbomer (0.3%, 0.3 ml) was injected into the left anterior chamber. A group of rabbits were randomly killed after 1, 2, 3, 4, 6, 8, 10 and 12 weeks. The anterior chamber of the rabbit eye specimens was observed. IOP increased slowly following the application of the drug, high IOP lasted for 3 months. The drug-induced changes of anterior chamber angle consisted of early inflammatory response and late fibrous changes. Inflammatory response occurred in early stage and reduced or disappeared after 3 weeks. Fibrous degeneration and adhesion obstruction occurred in the anterior chamber angle after 4 weeks. Under the electron microscope, the trabecular was expanded and deformed, with hyperplasia of collagen and elastic fibers. Endothelial cells were separated from the trabecular, and showed the morphology of lymphocytes, with the function similar to the macrophages. Phagocytized Carbomer particles were transported through the vacuoles of Schlemm's canal endothelial cells. Large vacuoles gradually reduced. Excessive Carbomer particles were accumulated in the endothelial cells and obstructed the Schlemm's canal. This induced the fibrous proliferation and the destruction of anterior chamber angle structures. The obstruction of aqueous humor outflow induced by compound Carbomer in rabbit high IOP model is caused mainly by the changes in trabecular endothelial cells.