OCT Penlight

Sara Hanrahan

Brock Nichol

Gina Rodriguez

Areej Sajjad

University of PittsburghSenior Design - BioE1161

Outline• Background

• Objectives

• Product design specifications

• OCT Penlight design

• Results

• Budget

• Validation & verification

• Future work

What is Glaucoma?

• Damage to the optic nerve that may lead to vision loss or complete blindness

• 66.8 million people with visual impairment• 6.7 million suffering from blindness [1]

[1] http://www.ahaf.org/glaucoma/about/glabout.htm - Accessed December 4, 2007

Possible Cause of Glaucoma

• Schlemm’s canal clogged, preventing aqueous humor from escaping

• High intraocular pressure (IOP)

Cassin, B. and Solomon, S. Dictionary of Eye Terminology. Gainsville, Florida: Triad Publishing Company, 1990.

Canaloplasty: A Promising Solution

• Expand Schlemm’s canal to relieve IOP

• New, safe, and minimally invasive technique (do not have to enter anterior chamber)

• Biggest challenge: surgeon has to find Schlemm’s canal

Market Size

• In 1999, 400,320 glaucoma surgeries were conducted in the US [2]

• These patients could benefit from the OCT Penlight

• There are approximately 7,500 hospitals in the US [3]

[2] Strutten, Walt, J Glaucoma. 2004 Jun;13(3):221-6.[3]http://www.census.gov/PressRelease/www/releases/archives/

facts_for_features_special_editions/004491.html

Optical Coherence Tomography (OCT)

• Acquires a cross-sectional image of the eye

• Penetrates about 2 mm into tissue

• High resolution imaging technology

• Currently used for diagnostic purposes

OCT Handheld

Real-Time Tomographic Reflection (RTTR)

Stetten, G., Chib, V., Hildebrand, D., Bursee, J. “Real Time Tomographic Reflection: Phantoms for Calibration and Biopsy.” IEEE/ACM International Symposiium on Augmented Reality. 2001 Oct:11-19. New York City.

Objectives

• Long term goal:• Locate Schlemm’s canal with more ease

during surgery

• Short term goal:• Place a 30 gauge needle into a goat eye

guided by the OCT penlight

OCT Penlight Components

MechanicalComponent

Calibration Arm

Product Design Specifications

• Place virtual image accurately (100 µm tolerance)

• Allow a sufficient working area

• Weigh less than 2 lbs

• Clamp onto a 3 cm diameter lens

• Software and hardware capable of acquiring image from OCT device

Mechanical Design

• Virtual image plane must be placed along OCT scanning beam

• Must be structurally stable

• Must be fixed display

virtual image

mirror

Electronic System

Handheld OCT

VGA Signal Splitter

Signal Analysis

Computer

OCT Software Display

OCT Penlight Computer

OCT Penlight Display

Patient

VGA Capture Device

Handheld OCT

VGA Signal Splitter

Signal Analysis

Computer

OCT Software Display

OCT Penlight Computer

OCT Penlight Display

Patient

VGA Capture Device

Handheld OCT

VGA Signal Splitter

Signal Analysis

Computer

OCT Software Display

OCT Penlight Computer

OCT Penlight Display

Patient

VGA Capture Device

Handheld OCT

VGA Signal Splitter

Signal Analysis

Computer

OCT Software Display

OCT Penlight Computer

OCT Penlight Display

Patient

VGA Capture Device

Handheld OCT

VGA Signal Splitter

Signal Analysis

Computer

OCT Software Display

OCT Penlight Computer

OCT Penlight Display

Patient

VGA Capture Device

Handheld OCT

VGA Signal Splitter

Signal Analysis

Computer

OCT Software Display

OCT Penlight Computer

OCT Penlight Display

Patient

VGA Capture Device

Handheld OCT

VGA Signal Splitter

Signal Analysis

Computer

OCT Software Display

OCT Penlight Computer

OCT Penlight Display

Patient

VGA Capture Device

Handheld OCT

VGA Signal Splitter

Signal Analysis

Computer

OCT Software Display

OCT Penlight Computer

OCT Penlight Display

Patient

VGA Capture Device

Software

Capture Screen

Crop Display

Display our software using OpenGL + GLUT

Scale X

Scale Y

Rotate

Translate

Calibration• Purpose

• Guide user in positioning the virtual image to its accurate location on the scanning plane

• Process

• 3 pins within scanning range

• Pins scanned and image displayed

• User aligns virtual image

• Easily detached

4.5 mm

2 mm

Prototype Fabrication

• Stereolithography (SLA)

• Lightweight

• Cost-efficient

• Sufficiently sturdy

• Readily available

Final Product

A: Flexible armB: OCT Handheld DeviceC: Lens of OCTD: OLED DisplayE: Half-Silvered MirrorF: Calibration Arm

Calibration Set Up

Calibration Process

Displaying the Virtual Image

mirror

Testing the OCT Penlight

QuickTime™ and aMPEG-4 Video decompressor

are needed to see this picture.

QuickTime™ and aMPEG-4 Video decompressor

are needed to see this picture.

Validation & Verification

• Allow a sufficient working area• Approved by an experienced ophthalmologist

• Weigh less than 2 lbs• Using a scale, we weighed entire device

• Clamp onto a 3 cm diameter lens• OCT Penlight was able to clamp onto lens and

maintain position for at least two hours

Validation & Verification• Software and hardware capable of acquiring

image from OCT device• Run the software and see if image on monitor is

visible on the Penlight display

• Placement of virtual image must be accurate (100 µm tolerance)• Examine calibration process through a

microscope

• Objective must be met• Guide user in penetrating a goat eye with a 30

gauge needle using OCT Penlight

Future Work

• Use a higher quality microscope to obtain clearer pictures of the virtual image

• Attach OCT Penlight directly to surgical microscope

• Automate calibration

• Test Penlight on live specimens

• Make software faster• More efficient video capture

BudgetItem Approximate

CostAdditional Notes

Mirror $10 Already availableOLED Display $800

Rapid Prototyping

$300 Stereolithography

VGA Splitter $100VGA to USB

Video Capture Device

$300

Cow Eyes $2.50 eachFlexible Arm $38OCT Scanner $85,000 Normally available in most

hospitals and does not require purchasing

Project Management

1-Jan 11-Jan 21-Jan 1-Feb 11-Feb 21-Feb 1-Mar 11-Mar 21-Mar 1-Apr 11-AprInitial ResearchMechanical DesignPenlight PrototypingElectronics and Software DesignCalibration DesignCalibration Arm PrototypingInitial TestingDesign ExperimentLab Testing

Acknowledgements

• Sources of funding• Generous gift of Drs. Hal Wrigley and Linda Baker

• Department of Bioengineering

• Mentors• Dr. George Stetten

• Larry Kagemann

• Additional help• Andy Holmes

• Gaurav Shukla

• Dr. John Galeotti

• Dr. Bing Wu

• Dr. Gadi Wollstein

Questions