Understanding patterns of retinal haemorrhage

A problem presented at the UK MMSG Cambridge 2014.

Presented by:
Richard Bonshek (Manchester Royal Eye Hospital, Central Manchester University Hospitals)
Participants:
R Bonshek, SJ Cowley, OE Jensen, P Pearce, A Ravi, JH Siggers, P Stewart, RJ Whittaker, M Zouache

Problem Description

Patterns of retinal bleeding are important as signatures of injury or disease. Certain patterns of retinal haemorrhage are considered to have significance as a marker for head trauma. In trauma, retinal haemorrhage may occur as a primary result of head injury or as a secondary phenomenon due to raised intracranial pressure, and there is disparity between clinical observations of retinal haemorrhage and most biomechanical approaches to thresholds of retinal vascular damage. Thus approaches based upon considerations of the contribution of raised intracranial pressure and intravascular pressure - and particularly the rate of increase of these quantities - are of importance.

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Study Group Report

We examine a potential mechanism of localised bleeding in the optic nerve sheath arising from head injury in infants. We consider how a rapid deformation of the skull leads to a rapid rise in intracranial pressure, which in turn creates a disturbance that propagates along the cerebrospinal fluid (CSF) in the optic nerve sheath subarachnoid space (ONSAS). The skull is modelled mathematically as a set of hinged plates and the ONSAS as a collapsible fluid-filled channel. Our model predicts that the propagating disturbance steepens into a shock at its leading edge, and that reflection of the disturbance at the closed end of the ONSAS leads to locally elevated CSF pressure. This may provide a mechanistic explanation for bleeding in the ONSAS close to the back of the eye. Our study demonstrates how mathematical modelling can provide insights into mechanisms of trauma in situations where human or animal experiments are inappropriate.

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Follow-Up Activities

The following follow-up meetings have occured to continue work on aspects of this problem:

2014 Retinal Haemorrhage Follow-Up Meeting
Friday 14th November 2014, University of Manchester