Corneal Membrane Transplant Injector

Kristen BergerPaul BieniekDavid Brooks

Marie Gill

Dr. Ahmed Al-Ghoul

April 13, 2007

Cornea Surgery

• Keratoplasty is used to treat many cornea diseases

• 2005 – Over 100,000 surgeries performed in U.S.

• More efficient surgical techniques have recently evolved (DSEK)

http://sarajdoktor.blogger.ba/

Current Surgery Techniques: DSEK

• 50% of keratoplasty procedures

• Advantages• Only replaces diseased tissue• Smaller incision• Fewer stitches

• Disadvantages• Donor tissue folded and

inserted• Damage to endothelial cells • Interface haze• Loss of intraocular pressure

Gorovoy, M. S., Francis, W. P.

Eye Anatomy

ANTERIOR C

HAMBER

Design Objectives

• Safely deliver donor tissue to anterior chamber

• Minimize contact with endothelium

• Reduce incision size (<4mm)

• Maintain intraocular pressure

Requirements

• Compatible with existing equipment• Functions:

• Irrigation• Aspiration

• Easy to operate • Sterilizable • Biocompatible• Life in service - 5 years at 5

procedures/week

Competitive Analysis

• Currently, no device performs the same function

• Similar devices• Irrigation/ aspiration

devices• Lens implant devices

http://www.hsc.wvu.edu/som/eye/servicesCataract.asp

Design Alternatives

• Curled membrane• Translatable suction

platform• Too much friction

1.) 2.)

• Wrapped membrane• Translatable oval suction tip• Triple lumen design

Design – End of First Semester

• Three component system

• Stainless steel injector

• Clear plastic cartridge

• Stainless steel case

• Fabrication

• “If you guys think you can make

this, you’re crazy!” – Andy Holmes

• Injector too complex to be machined as one piece

Redesign Issues

• Design for Production – Consider Assembly

• Vacuum and irrigation tubes; luer fittings

• Simplification

• Merging of case and cartridge

Prototype Fabrication

• Cartridge – SLA

• Injector parts

• Stainless steel, SLA, PVC

• Used lathe and mill

• Hand-assembled

Features

Pin and guidance track to allow precise alignment of parts

Luer fittings for attachment to emulsifier

O-rings for water-tight seal between parts

Clear plastic cartridge for visualization during use

Surgical grade stainless steel for injector

Ergonomic grips

Potential Hazards

• Damage to donor endothelial cells Category III

• Inability to maintain the anterior chamber Category III

• Failure to achieve suctionCategory III

• Negative reaction of tissue to the device Category IV

• Damage to patient’s eyeCategory IV

Severity:Category I - Catastrophic

Category II - Critical

Category III - Marginal

Category IV - Minor

Concept Model

• Testing of suction and irrigation on silicone corneas and contact lenses

Preliminary Prototype Testing

• Test functions:

• Suction

• Irrigation

Future Prototype Testing

• Qualitative using animal cadaver eyes• Ease of use - ergonomics • Function

• Works with phacoemulsification machine• Holds corneal membrane on injector• Maintains anterior chamber pressure• Safely transports the corneal membrane

• Histology testing of corneal membrane and recipient eye

Qualitative Testing Matrix

Prototype Feature

Poor Fair Marginal Good Excellent

Ease of use/ ergonomics

Needed incision size

Attaches corneal membrane properly

Maintains anterior chamber pressure

Corneal transplant procedure time

FDA – Classification I

Similar Devices:Intraocular lens guide• 21 CFR 886.4300

• “… a device intended to be inserted into the eye during surgery to direct the insertion of an intraocular lens and be removed after insertion is completed.”

Ocular surgery irrigation device• 21 CFR 886.4360

• A device used “… during ophthalmic surgery to deliver continuous, controlled irrigation to the surgical field.”

FDA – Classification I

• General Characteristics

• Non-life sustaining

• Least complicated

• Failure poses little risk

• Premarketing submission 510(k)

• Substantially equivalent to a legally marketed device not subject to a premarket approval (PMA)

• Intraocular lens guide is exempt from 510(k) unless “ . . . if used as folders and injectors for soft or foldable IOL's.”

FDA – Classification I

• General Controls:

• Quality assurance program

• Suitable for intended use

• Adequately packaged

• Properly labeled

• Establishment registration

• Device listing forms

Economic Considerations• Cartridge

• ~50,000 DSEK procedures per year in US• $1.10/cartridge production cost1

• Injection mold: $15,000-25,0002

• ABS: $2.00/lb2

• Revenue = ($100 – $1.10)*50,000 = $5M per year

• Injector• ~2,500 Hospitals and Surgery Centers• $100/injector3 (CNC)• $20/injector4 (MIM)• Injection mold: $25,0004

• Revenue = ($1500 - $20)*(2,500 hospitals)*(3 units/hospital)/(5 yrs)

= $2.2M per year

1) http://www.geplastics.com/gep/eng/webted/webted.html

2) http://kazmer.uml.edu/Software/JavaCost/index.htm

3)http://www.jobshoptechnology.com/features/0302/mim.shtml

4) http://news.thomasnet.com/IMT/archives/2004/05/the_benefits_of.html?t=archive

Project Management

Initial Research and Design

Proof of Concept

Redesign

Fabrication

Prototype Testing

Prototype Completed 4/6/07

Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May

Concept proved 2/8/07

Team Contributions

• Dave – Initial SolidWorks design, background research

• Paul – Initial SolidWorks design, cartridge development, fabrication

• Marie – Concept model testing, preliminary prototype testing, FDA regulatory research

• Kristen – SolidWorks redesign, injector development and fabrication

• All – DHF and SBIR

Future Directions

• Biocompatibility Testing

• Plastic tip redesign

• Decrease size

• Conduct stress tests

• Make tip slanted

• Durability Testing

• Upscale to mass production

Acknowledgements

• Dr. Ahmed Al-Ghoul

• Andy Holmes

• Generous gift of Drs. Hal Wrigley and Linda Baker

• Department of Bioengineering

Thank You!

• Questions?