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SUMMARY:Fluid dynamics of the aqueous humour of the eye - Jennifer Tweedy\
 , University of Bath
DTSTART:20260320T160000Z
DTEND:20260320T170000Z
UID:TALK243412@talks.cam.ac.uk
CONTACT:Duncan Hewitt
DESCRIPTION:Nearly 3% of people in the UK are living with some degree of s
 ight loss\, and fluid mechanics plays an important role in many of the und
 erlying conditions.\n\nThe eye is a pressurised container\, and this leads
  to several fascinating mechanical phenomena. The intraocular pressure (IO
 P) is maintained by the flow dynamics of the aqueous humour\, and constrai
 ned outflow of this fluid leads to glaucoma\, a common cause of sight loss
  affecting about 2% of those aged over 40 years. This fluid is produced in
  the posterior chamber (the region between the lens and the iris) and from
  there it flows anteriorly through the pupil (a hole in the iris) into the
  anterior chamber (at the front of the eye between the iris and the cornea
 ). It then leaves the eye by two main routes: the so-called conventional a
 nd unconventional outflows.\n\nI will start by describing my research on t
 he unconventional outflow\, which is a seeping flow through the tissues of
  the eye. The tissues are modelled as porous media\, while osmotic pressur
 e differences between the plasma in the blood capillaries in a layer of ti
 ssue (choroid) supplying the retina and the interstitial fluid in the tiss
 ue surrounding these vessels in the choroid are captured by accounting for
  albumin concentration\, and modelling the albumin transport. There is als
 o a narrow gap (suprachoroidal space\, SCS) between the choroid and sclera
  (the white of the eye)\, and its thickness is hypothesised to depend on p
 ressure differences\; we show that the fluid flow in this gap plays an imp
 ortant role. The tissues involved are thin\, and we exploit this to simpli
 fy the equations considerably\, resulting in four ordinary differential eq
 uations to describe the flow dynamics and albumin transport\, which can be
  solved numerically.\n\nDrugs to treat primary open-angle glaucoma act by 
 increasing the unconventional flow\, and we use the model to investigate t
 heir action. We also extended the model to include the presence of an impl
 anted device to treat glaucoma\, connecting the anterior chamber to the SC
 S\, which relieves the IOP by bypassing some of the tissues in the unconve
 ntional outflow. \n\nI will more briefly describe three pieces of research
  on the flow dynamics of the aqueous humour in the anterior and posterior 
 chambers. Drivers of this flow include pressure differences\, thermal effe
 cts and eye rotations. The analysis is greatly simplified by making use of
  lubrication theory\, and we use the results to investigate both the flow 
 in health and the flow in the presence of treatments for various eye condi
 tions.\n\nIf time permits\, I will describe work to understand the flow of
  the vitreous humour. This is a gel that lies in an approximately spherica
 l chamber behind the lens and in front of the retina\, constituting about 
 80% of the volume of the eye. Its flow is driven primarily by eye rotation
 s. We idealise the geometry\, fluid rheology and rotations\, and these app
 roximations permit a semi-analytical solution for the flow\, driven by sma
 ll-amplitude rotations\; the steady streaming component of this flow plays
  a key role in mass transport. In further work\, the simplifying assumptio
 ns are relaxed.\n\n
LOCATION:MR2
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