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.
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
clinically 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.
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.