Eye2Brain Level 0 Application

Eye2brain Level 0 is a lumped-parameter model developed in OpenModelica, which simulates the blood circulation in the retina and in the lamina cribrosa.

1. Model

The model describes the the blood circulation from the central retinal artery (CRA) through the lamina cribrosa and the retinal arterioles till the capillaries. Therefore the blood is drained via the venules and finally collected in the central retinal vein (CRV).

The retinal circulation (Fig. 1) is described using the analogy between the flow of a fluid in a hydraulic network and the flow of current in an electric circuit. In particular resistors represent the resistance to flow offered by blood vessels, whereas capacitors model the deformability of vessel walls and theiability to store blood volume.

Level0 circuit scheme
Figure 1. Retinal circuit scheme

2. Input

The input of this model are

  • the intraocular pressure (IOP) that is modelled as a ramp voltage source;

  • the retrolaminar tissue pressure (RLTp) that is represented by a constant voltage source;

  • the central retina artery (CRA) pressure that is characterized by a voltage source and it is univocally defined by the heart rate (HR), the systolic blood pressure (SBP) and diastolic blood pressure (DBP).

It is possible to modify the values (in mmHg) of the simulation in the config file:

[eye2brain]
level0=true
IOP=16.0
RLTp=7.0
HR=60
SBP=120
DBP=80

3. Output

Currently available output in Feel++ model:

  • blood velocities in retinal circulation. Those values are exported in a [time,value] .csv file. For example the blood velocity in CRA/CRV. The results by default are in e2b_level_zero/np_4/fmu_values.csv

4. Running the case

mpirun -np 4 feelpp_e2b_omvs --config-file eye2brain/level0.cfg

5. Advanced Usage

5.1. Advanced Numerical Inputs

Here we list the main important numerical input:

  • output directory:

directory=e2b_level_zero/

  • start/step/stop time:

[ts]
time-initial=0
time-step=0.1
time-final=1

  • fmu circuit input/output data:

[fmu]
filename=$cfgdir/retina_final.fmu
solver.time-step=0.0002
#blood pressure drop on the lamina
exported-variables=lcR.v
# blood flow within the lamina
exported-variables=lcR.p.i
# CRA blood flow
exported-variables=R1a.p.i
# CRV blood flow
exported-variables=R5a.n.i