Studies of fluid movement in the eye

Moseley, Henry (1980) Studies of fluid movement in the eye. PhD thesis, University of Glasgow.

Abstract

Although much work has been carried out on the movement of many substances into and out of the vitreous, very little is known about the transfer of water. In order to facilitate subsequent analysis, studies were performed using an inert tracer, xenon-133 dissolved in saline, as well as tritiated water. Chapter 1 forms an introduction to the thesis. It details relevant anatomy and simimarises previous work in the field, drawing attention to gaps in present knowledge. Chapter 2 describes experiments in which xenon-133 was injected into the vitreous of rabbits and subsequently collected in one of the vortex veins draining the choroid, on the sclera and in the anterior chamber. It was found that most of the xenon-133 was removed in the blood of the choroid. The experiments outlined in Chapter 3 are analogous to those of the previous chapter, hut in this case, tritiated water was the tracer under study. As with xenon-133, most of the tritiated water from the vitreous left the eye in the blood of the choroid. The rates of removal of the two isotopes were also comparable. It is evident that the ordinary water molecules in the vitreous are being changed rapidly with a mean transit time from mid-vitreous to choroid of approximately 30 minutes. A mathematical model of diffusion is developed in Chapter 4. The model is based on three-dimensional diffusion from the vitreous through the eye with removal occurring in the choroid. Because of symmetry, only a two-dimensional solution is required. The results of the mathematical model are given in Chapter 5. It is shown that xenon-133 experimental results are consistent with a diffusional explanation. The model is then applied to tritiated water where there is also good agreement between experiment and the diffusional model. The above chapters relate to fundamental properties of water in the vitreous. It has been suggested in the literature that because of hydrostatic pressure differences, a flow exists across the retina. This is examined in Chapter 6. The existing model for hydrostatic pressure-induced flow across the posterior layers of the eye is shown to be inadequate and a new model presented. No firm conclusion may be drawn concerning the magnitude and direction of this flow but it is thought that pressures are likely to equalise and prevent such a flow occurring. Aqueous humour leaves the eye through pores in the lining endothelium of Schlemm's canal. In Chapter 7, calculations of the pore fluid resistance are presented, based on different pore geometries. The contribution of the pore to the total outflow resistance is determined at different intraocular pressures and with and without treatment using pilocarpine. A final discussion and conclusions are presented in Chapter 8.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Advisers: Professor W.S. Foulds, Dr. F.C. Gillespie and Dr. R. Strang.
• Keywords: Ophthalmology
• Subjects: R Medicine > RE Ophthalmology
• Colleges/Schools: College of Medical Veterinary and Life Sciences
• Date of Award: 1980
• Depositing User: Enlighten Team
• Unique ID: glathesis:1980-72105
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 17 May 2019 12:59
• Last Modified: 15 Aug 2022 10:36
• Thesis DOI: 10.5525/gla.thesis.72105
• URI: https://theses.gla.ac.uk/id/eprint/72105