Fig. 1From: Vitreoretinal instruments: vitrectomy cutters, endoillumination and wide-angle viewing systemsFlow rate of a pure/aqueous fluid according to the “Poiseuille’s law”; ∆P is the pressure difference across the length of the probe needle, r is the inner radius of the vitrectomy probe, η is the viscosity of the fluid and L corresponds to the length of the vitrectomy tubeBack to article page