Figure 4. Photomicrograph of a highly myopic optic nerve head (staining: PAS); black stars: inner border of the optic nerve; arrows #1: pia mater of the optic nerve; arrows #2: peripapillary scleral flange as roof of the widened orbital cerebrospinal fluid space; arrows #3: dura mater of the optic nerve; arrow #4: arterial circle of Zinn-Haller; A–B: Pia mater (potentially the “peripapillary scleral ring” upon ophthalmoscopy); B–C: Delta zone (no blood vessels >50 µm diameter within gamma zone); C–D: remaining Gamma zone (peripapillary sclera without overlying choroid, Bruch's membrane and deep retinal layers).
