Schematic representation and spectral domain optical coherence tomography (SD-OCT) examples of optic nerve head delineations. Black dots (white arrows) in the B-scans indicate the SD-OCT structure corresponding to the clinically visible optic disc margin. A, The Bruch’s membrane opening (BMO) corresponding to the optic disc margin when BMO was coincident with the innermost edge of Bruch's membrane and border tissue (A1 and A2) or when there was a Bruch's membrane overhang (A3). B, Bruch's membrane/border tissue corresponding to the optic disc margin when the innermost edges of Bruch's membrane and border tissue did not coincide. C, Border tissue alone corresponding to the optic disc margin.