Fig. 1
From: Optic nerve sheath diameter at high altitude: standardized measures in healthy volunteers
Ultrasound measurements technique. A–B: The transducer positioned on the transverse axis with an initial angle of 25° and tilted until the optic nerve and the papilla were visualized. C: Optic nerve and papilla with color doppler mode showing the central vessels of the retina, the ciliary vessels and measurement performed using central vessels of the retina direction and landmarks from the ciliary vessels. D–E: The transducer positioned on the vertical axis. F: Optic nerve and papilla with color Doppler mode showing the central vessels of the retina, the ciliary vessels and measurement performed using central vessels of the retina direction and landmarks from the ciliary vessels