Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK.
Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
Acta Ophthalmol. 2021 Mar;99(2):e209-e214. doi: 10.1111/aos.14539. Epub 2020 Jul 23.
Emulsification of silicone oil (SiOil) in a vitrectomized eye was investigated using a 3D model of the vitreous cavity to test the hypothesis that oil droplet formation arises from the breakdown of the bulk SiOil-aqueous interface during eye saccadic movement.
Round bottom flasks filled with SiOil and a saline phase modelled the vitrectomized SiOil-filled eye. A stepper motor imposed saccadic movements and the oil/aqueous interface was monitored with digital cameras. A range of SiOil viscosities, flask diameters, motion scenarios and levels of fill were studied. Estimates of velocity profiles in the fluid on the equatorial plane of a sphere subject to saccadic motion were obtained from an analytical solution to the Navier-Stokes equations.
Interfacial waves were observed at saccadic motions with higher acceleration, amplitude and frequency. Low interfacial tension between the two fluids, lower oil viscosity and smaller level of SiOil fill all promoted large deformations of the interface. No droplets were formed at the bulk SiOil-aqueous interface. However, formation and detachment of oil droplets were observed at the three-phase contact line under certain conditions.
The stresses generated at the liquid-liquid interface are not large enough to form droplets in the bulk region for conditions representative of these in the eye. Bulk emulsification of the SiOil, reported as the main formation mechanism by some workers, is not responsible for droplet formation in a vitrectomized SiOil-filled eye set-up. This result confirms recent finding on droplet formation driven by a surface emulsification mechanism.
通过玻璃体腔的 3D 模型研究硅油（SiOil）在玻璃体切割眼中的乳化作用，以验证以下假设：油滴的形成源于眼跳动运动过程中 bulk SiOil-水界面的破裂。
填充有 SiOil 和盐水相的圆底瓶模拟了玻璃体切割填充 SiOil 的眼睛。步进电机施加眼跳动运动，并用数字摄像机监测油/水界面。研究了一系列 SiOil 粘度、瓶径、运动方案和填充水平。从纳维-斯托克斯方程的解析解中获得了球体赤道平面上流体在眼跳动运动下的速度分布估计。
在具有更高加速度、幅度和频率的眼跳动运动中观察到界面波。两种流体之间的界面张力较低、油粘度较低和 SiOil 填充水平较低都会促进界面的大变形。在 bulk SiOil-水界面处没有形成液滴。然而，在某些条件下，在三相接触线处观察到油滴的形成和脱离。
在代表眼部条件的情况下，在 bulk 区域产生的液体-液体界面的应力不足以形成液滴。一些研究人员报道的 bulk SiOil 乳化作用是主要的形成机制，但不能解释玻璃体切割填充 SiOil 的眼中液滴的形成。这一结果证实了最近关于由表面乳化机制驱动的液滴形成的发现。
