The study aimed
was to create and validate a computational model
that describes the deformation characteristics of the corneas mounted in an
artificial anterior chamber in response to an air puff. 

A
2-D (COMSOL Multiphysics model) of an air jet impinging on cornea mounted in an
artificial anterior chamber was created. The CorVis ST, a device that used to
evaluate deformation response in the corneas, was generated the physical air
jet. This air jet was characterized with hot wire anemometry to acquire spatial
flow velocity data. The hot wire was placed at the jet exit on the CorVis, and
then moved outward with micrometer control to distances of 3, 6, 9, 12, 15, 20,
and 25 mm along the centerline. The duration of the hot wire anemometry
recordings continued 40 ms. Initial data of the temporal profile shows that the
peak velocity along the centerline during the air puff at distance 0 is over
100 m/s. On the other hand, the peak velocity reaches above 90 m/s at distances
between 9 and 12 mm from nozzle of the CorVis ST. Accordingly, the model inlet
velocity representing the CorVis ST was set at 100 m/s. Corneal dimensions were
modeled by constructing an ellipse inside an 8mm sphere that was sectioned to
have a width of 12 mm. The cornea section was mounted onto a rigid body within
the model, representing the Barron’s Artificial Anterior Chamber. Intraocular
pressure (IOP) was manipulated to be 10, 20, 30, 40, and 50 mmHg. Deformation
data from a corneal-scleral rim mounted on an artificial anterior chamber at
these pressures was used to validate the model. The model was run iteratively
at each pressure to determine the Young’s modulus required to produce
experimentally determined deformations.

 The
result show that maximum deformation amplitude for the model was matched to
experimental deformation data within 0.01% error. The Young’s moduli were
1.569, 1.740, 1.899, 2.099, and 2.250 MPa for pressures of 10, 20, 30, 40, and
50 mmHg, respectively.

The model supports the
relationship between the IOP and the cornea that as IOP increases, the cornea
will become stiffer. Future studies will develop a 3D model as well as modeling
the whole globe.

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