A surgical technique for decreasing intraocular pressure comprising a two-tiered approach to Schlemm's canal and the trabecular meshwork, was done in 660 heavily pigmented eyes in South Africans of colour and followed for ten years. The canal is opened and maintained with the instillation of viscoelastic, and a "clear window" is created over Descemet's membrane to facilitate continuous leakage of aqueous from the anterior chamber. The second tier is excised and the first tier is sutured tightly to the adjacent sclera, taking great care not to cauterise or injure the "collecting channels" on the surface. This technique was done on both primary and secondary glaucomatous eyes and offers excellent results and minimal complications (AU)