Document the clinical characteristics and clinical course of primary glaucoma in the beagle. Determine its mode(s) of inheritance. Evaluate the mydriatic, corticosteroid and water provocative tests in control and affected beagles. Calibrate the Schiotz, Ton-Air, Halberg & Mackay-Marg Tonometers in the dog. Determine the facility of outflow in affected dogs by Schiotz tonography & constant pressure perfusion at different stages of the disease. Using nitroblue tetrazolium chloride determine aqueous outflow from the anterior chamber of the normal & glaucomatous eye. Measure ocular fundus degeneration by serial fundus photography, electroretinography & fluorescein angiography in both chronic & acute elevations of intraocular pressure. Determine the histopathology of the ocular tissues in primary glaucoma of the beagle. Light & electron microscopy will be used. Establish a potential spontaneous biomedical model for primary open angle glaucoma in man.