1. Group 21 Eye Muscle Prosthesis
Team Members:
Brett Boskoff Matt Patton Jeff Tse
Advisors:
Leonard Pinchuk, Ph.D., D.Sc.
Stewart Davis, M.D.
Innovia LLC

2. Problem Statement Extraocular Muscle Strabismus Double Vision
Amputation
Dysfunction
Paralysis
Strabismus
Incidence of 64.1/100,000 patients younger than 19 years old, corresponding to a prevalence of 1.0% of all children younger than 11 years of age
Double Vision
Specific problem we are designing for

3. Previous Solutions Eye patch or special (prism) spectacles
Permanently suture eye into primary position
Stretchable band made of elastic material
Previous solutions, their features, and their disadvantages

4. Design Approach Nose EYE Dacron muscle-suture platform
Titanium T-plate
Insertion of medial rectus
Tube (vertical bar of T-plate)
EYE
Design approach, features, and improvements on previous implants
Spring coil/ elastomer
Non-absorbable suture
Titanium ball

5. Prosthesis
Prosthesis

6. Component Materials / Properties
Titanium T-plate
Nitinol spring
Elastomer (QuatromerTM)
Dacron platform
Materials of prosthesis components and their properties with respect to biocompatibility, spring memory, and history as biomaterial

7. Project Goals Create a prototype of the prosthesis
Develop a proof-of-concept model

8. Completed Work
Identified the spring constant range involved with the extraocular muscles
~30g of force to keep eye in primary position
~1g per degree of eye rotation
Preliminary spring testing
Spring wire diameter= ~0.006 ± in
Mandril diameter= ~0.02 ± 0.01 in
Obtained skull for our model
Through literature research and consultations with ophthalmologists, we have identified the approximate forces involved with the extraocular muscles. Approximately 30g of force is needed to keep the eye in the primary position. Furthermore, approximately 1g of force per degree of rotation of the eye from the median is needed to turn the eye. However, it must be noted that since obtaining actual extraocular muscle forces and assuming the values apply to all humans is impractical, the validity of these values cannot be definitively substantiated. Therefore, we believe testing the eye muscle prosthesis in animals and eventually humans will ultimately predicate its function and spring force.
We have performed preliminary spring testing to determine ballpark dimensions of our springs with respect to the identified extraocular muscle forces.
You don’t have to say exactly what I wrote, and I don’t think you have to say the specific numbers from the prelim spring testing, only mention we have identified them.

9. Future Work Determine component dimensions for:
T-plate (vertical length)
Continue manufacturing springs and load testing