Retinopathy of Prematurity Instrument Design Team

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Retinopathy of Prematurity Instrument Design Team

• Mike Latos
• Jeff Toone

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Project Overview

• Each year about 400,000 babies are born
  prematurely
• Retinopathy of Prematurity occurs in several
  thousand cases every year
• Nearly 500 are blinded by the disease

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Retinopathy of Prematurity

• Blood vessels in eye stop growing
• Fibrous scar tissue forms (lack of oxygen)
• Scar tissue attaches itself to retina
• Scar tissue begins to retract
• Enough scar tissue will detach retina
• Infant goes blind

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What To Do?

• Doctors must examine babies retina to see if
  surgery is necessary
• The instruments used to test the babies are a
  scleral depressor and an eyelid speculum

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The Problem

• The instruments are made of high quality surgical
  steel (120/set)
• Mucosa of the eye can harbor dangerous pathogens
• Sterilization is very costly and labor intensive
• The instruments to test the babies are small and
  easily lost, thrown away, or misplaced

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The Customers

• The customers are hospitals that do Retinopathy
  of Prematurity eye examinations such as Riley or
  Methodist

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The Customers Needs

• Riley Hospital has requested the development of
  an affordable, sterile alternative to the current
  speculum and scleral depressor with the
  possibility of disposable methods.

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The Engineering Requirements

• Ease of use
• Static tension
• Low failure rate
• disposable

• Sterile production
• Smooth surfaces
• Low production costs
• Strength
• Rigidity

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Concepts and Brainstorming(Eyelid Speculum)

• Spring mechanism
• Flexible polymer
• Inflatable ring

• Screw mechanism
• Flexible ring
• Clip-on

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Concepts (Speculum)
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Speculum Black Box
Energy Out
Separated?
Separated!
Positioned?
Positioned!
Note Diagram depicts preparation and use or
Positioning and Separation steps respectively.
The conclusion Or Removal step is not shown as
it is very similar to the Position step.
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Concept Evaluation
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Concepts (Speculum)
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Polyurethane

• Good mechanical and elastic properties
• Can be produced sterilely and with smooth edges
• Good memory (return to original position)
• Recyclable

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Concepts (Depressor)

• Disposable snap-on
• Disposable one piece

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Process of Actual Design

• Actual speculum drawn in ProE and imported into
  ANSYS
• Forces analyzed to get appropriate separation of
  arms
• Stress and Strain analysis performed

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Actual ProE Model
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Actual IGS Import Model
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Actual ANSYS Model
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Actual Rotation About z-Axis
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Actual Stress
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Actual Stress contd
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Actual Strain
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Analyzing New Concept

• General shape of new speculum developed in ProE
  and imported into ANSYS
• Same force applied to new speculum
• Cross-sectional area changed until same angle
  obtained

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Conceptual ProE Design
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Conceptual IGS Import
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Conceptual ANSYS Model
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3/32 Design Rotation About z-Axis
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1/8 Design Rotation About z-Axis
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1/8 Design Stress
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1/8 Design Stress contd
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1/8 Design Strain
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Precision Manufacturing
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Precision Manufacturing
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Precision Detailing
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More Detailing
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Finished Product
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Scleral Depressor

• Same shape and size
• Made of Polyurethane polymer
• Too small to make prototype