nicole gullatt_project engages presentation (spring semester presentation)

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Modeling the Effects of Bruch’s Membrane Opening Shape on the Biomechanics of the Rat Model of Glaucoma Nicole Gullatt Dr. C. R. Ethier’s Lab Mentor: Stephen Schwaner May 16, 2016

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Page 1: Nicole Gullatt_Project Engages Presentation (Spring Semester  Presentation)

Modeling the Effects of Bruch’s Membrane Opening Shape on the Biomechanics of the Rat Model of Glaucoma

Nicole GullattDr. C. R. Ethier’s LabMentor: Stephen SchwanerMay 16, 2016

Page 2: Nicole Gullatt_Project Engages Presentation (Spring Semester  Presentation)

Glaucoma Overview: What is it?

• Glaucoma is a group of eye diseases involving optic nerve damage and usually involving an increase of intra-ocular pressure (IOP)

• Elevated IOP causes increased stressed and strain in the optic nerve head (ONH) tissues resulting in retinal ganglion cell death and preventing the transmission of visual information to the brain

• Treatment for glaucoma is centered around preventing further loss because eye damage and vision loss that has already occurred is irreversible

• Medications and surgical treatments for glaucoma focus on lowering a patient’s IOP, but are not always effective

Why the rat model is studied for glaucoma research: It is unethical to conduct scientific experiments on humans.

Rodent models are necessary for high throughput studies due to their low cost and ease of caring for

Rats present similar optic nerve head damage patterns to humans after experiencing elevated IOP

Page 3: Nicole Gullatt_Project Engages Presentation (Spring Semester  Presentation)

Biomechanics of the Optic Nerve Head (ONH)

• The complex pathophysiology of glaucoma is driven by biomechanics

• Elevated IOP leads to stress and strain in the ONH.

Stress: force per unit area

Strain: ratio of an object’s deformation to its original shape

• IOP related stress and strain can affect the delivery of nutrients to the RGC axons and axonal transport, and the activation of astrocytes in the ONH

• Distribution of stress and strain in the ONH is complicated

Page 4: Nicole Gullatt_Project Engages Presentation (Spring Semester  Presentation)

My Research Focus: Computer Modeling

1. Use design program Multiview to obtain 3-D point clouds of tissue geometry

2. Create 2-D circular plane (radius: 1 mm) with BMO shape in Rhino

3. Import 2-D plane into Abaqus and assign material properties:

Young’s Modulus: 3 MPa

Poisson’s Ratio: 0.49

Multiview Delineations of Histology Slide MR4-OD

BMO shapes acquired in Multiview

Circular Plane Rhino

Circular Plane with material properties in Abaqus

Page 5: Nicole Gullatt_Project Engages Presentation (Spring Semester  Presentation)

My Research Focus: Computer Modeling

4. Create polar coordinate system for 2-D Plane Section in Abaqus

Biaxial Displacement: 10 µm in radial direction

Boundary Condition: constrained in z direction

5. Mesh 2-D Plane in Abaqus

Meshing breaks geometrical figures into elements

6. Simulate stress and strain levels at locations in the eye using Abaqus

2-D Plane with loads and boundary conditions in Abaqus

Meshed 2-D Plane with elements in Abaqus

Solve the model in Abaqus to simulate strain levels around BMO

Page 6: Nicole Gullatt_Project Engages Presentation (Spring Semester  Presentation)

Results

Page 7: Nicole Gullatt_Project Engages Presentation (Spring Semester  Presentation)

Conclusion

Differences in 95th percentile strain of up to 30% were predicted between models.

This suggests that BMO shape could be an important factor in the rat model of glaucoma and that a more irregular BMO shape could potentially increase susceptibility to IOP-related damage in glaucoma.

Page 8: Nicole Gullatt_Project Engages Presentation (Spring Semester  Presentation)

Summer Research: Saponin Treatments for Pig TM Cells

• The trabecular meshwork is an area of tissue in the eye located around the cornea, responsible for removing the aqueous humor from the eye.

• Project Goal: Find the appropriate concentration of saponin to kill approximately 80% of pig trabecula meshwork cells to develop a glaucoma model.

Page 9: Nicole Gullatt_Project Engages Presentation (Spring Semester  Presentation)

Acknowledgments

• I wish to acknowledge Dr. C. R. Ethier, Stephen Schwaner, Eric Snider, and members of the Either Lab for their assistance with this research.

• Thank You!