“…Cannulas in all measured sizes except 27 G required greater forces for arterial penetration compared with correspondingly sized needles 25 . Regardless, blindness has been reported both with the use of blunt cannulas and sharp needles, 26 as has sight-threatening retro-orbital hemorrhage 27 . During HA administration, care must be taken to inject slowly so as to avoid undue for that could push HA into a vascular lumen.…”