Experimental investigations of the fluid dynamics of vitreoretinal surgery

IRENE NEPITA
2021
Vitrectomy is a surgical procedure by which the vitreous humour is removed from the vitreous chamber of the eye and is replaced with a tamponade fluid. Vitrectomy is performed by means of a system consisting of several components, including the vitreous cutter, which aspirates the vitreous body, a viscoelastic fluid that occupies the vitreous chamber of the eye. The vitreous cutter port geometry may have great influence in vitrectomy surgery from the fluidics and safety standpoints. For this
more » ... son, there has been an increase interest from ophthalmic companies in optimising the fluidics within the vitreous chamber during surgical maneuvers, in order to avoid retinal tractions and intraocular pressure (IOP) variations. Once removed, the vitreous is often replaced with Silicone Oils (SOs), which, however, inevitably tend to emulsify in the aqueous solution present in the eye, limiting the chances of using SOs as long term vitreous substitutes. Many months are indeed often required for complete healing of retinal damages. Moreover, formation of emulsions triggers local inflammatory processes, which can cause further complications. This thesis is an experimental work related to the physics of ocular surgical procedures and it consists of two main parts. The first part concerns the fluid mechanics of the vitrectomy procedure. In particular, experiments with different approaches have been performed on the fluidics of various vitrectomy systems, with the objective of identifying ideal working conditions that minimise the risks of retinal damages, while keeping the surgical procedure efficient. The second part is related to the characterisation of the interfacial rheology between SOs and aqueous solutions containing endogenous proteins released by the ocular tissue as a response to an inflammatory state. Aim of this part is to investigate to what extent biomolecules present in the aqueous solution can modify the rheological properties of the interface between the two fluids and, in turn, facilitate the formation of an em [...]
doi:10.15167/nepita-irene_phd2021-06-08 fatcat:wep3wipvwvccjpkhf7vo5w4hlu