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Sarah Moyer, CRA, OCT-CDirector of Ophthalmic Imaging

Kenneth L. Cohen, MDSterling A. Barrett Distinguished Professor

Kittner Eye CenterDepartment of OphthalmologyUniversity of North Carolina at Chapel HillSchool of Medicine

Clinical Applications of Anterior Segment OCT

No financial interest

Understanding Anterior Segment OCT

• Anatomy

• Vendors

• Clinical use of AS-OCT

• Technical aspects

• Measurements

• Artifacts

• Recent Cases

What Does Anterior Segment OCT Do?

2-dimensional cross section image of the anterior segment

Anterior Segment AnatomyLimbus Cornea

Angle

Anterior ChamberIris

LensPupil

Ciliary Body

Corneal AnatomyAir / tear interface

EpitheliumTear Film

StromaEndothelium

Kerataconus

Bullous Keratopathy

Hydrops

DSEK with fold

Cornea

Iris Cyst

Iris Neoplasm

Open Angle

Closed Angle

Courtesy Team Doheny Eye

High Pressure

Iris / Angle

Iris Cyst

LensAnterior Chamber IOL

Slipped LensCapsular Block

Imaging Lens

Conjunctiva / Sclera

Conjunctival Lesion

Scleral BucklePterygium

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Anterior Segment OCT Vendors

Bioptigen Handheld OCT

Heidelberg Spectralis with Lens

Optos Optos OCT/SLO

Optovue RT-Vue with CAM

iVue

Topcon SL Scan-1

3D OCT-2000

Zeiss Visante and Cirrus

Bioptigen

Courtesy of John CarpentierCourtesy of Sunita Sayeram and Joseph Vance

Heidelberg Spectralis

Courtesy of Tim Steffens

Optos OCT/SLO

Courtesy of Optos

Optovue RT-Vue with CAM

Courtesy of Optovue

Courtesy of Bruno Bertoni, CRA, OCT-C and Tamera Schoenholz, CRA

Corneal Scar Courtesy Team Doheny Eye

AC Tube Courtesy Ellen Redenbo and Mark Thomas

K-ProCourtesy Mark Thomas and Ellen Redenbo

Synechia Courtesy Team Doheny Eye

Courtesy Optovue

Topcon SL Scan-1

Not currently available in the US

Topcon 3D OCT-2000

Not currently available in the US

Topcon 3D OCT-2000

Photo Credit: Media Resources Centre

University Hospitals of WalesCardiff UK

Thanks Chris Tetley!

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Cirrus

Internal OpticsSoftware Upgrade needed

Two scan patterns

5-line raster 3 mm length, adjustable rotation and spacing

512x128 cube scan. 4mmx 4mm

Images courtesy of Martha Leen, M.D. & Paul Kremer M.D. Achieve Eye and Laser Specialists, Silverdale, WA

Closed Angle Glaucoma

Filtering Bleb

DSEK

Fuchs’ Dystrophy

Filtering Tube

Zeiss Stratus

Not FDA approved

Zeiss Stratus

Courtesy of Alexis Cullen, OCT-C, CRA

Zeiss Visante

Courtesy of Zeiss

Are you getting reimbursed for your AS-OCT?

Billing• 0187-T: Temporary Code, Medicare

reimbursement varied according to Medicare regions

• 92132: AMA established CPT code, Medicare covers this code. Some states may have a Local Medical Review Policy (LMRP) where only specific diagnosis are covered.

• SCANNING COMPUTERIZED OPHTHALMIC DIAGNOSTIC IMAGING, ANTERIOR SEGMENT, WITH INTERPRETATION AND REPORT, BILATERAL

1 Week After Phaco and 1-Piece Posterior Chamber IOL

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Dislocated IOLIOL in the Capsular Bag Tecnis One-Piece Causes of the Dislocted IOL

• IOL not in capsular bag but in ciliary sulcus

• Ruptured zonules

• Hole in posterior capsule

• Broken haptic

• Crimped haptic

Relationship Between the IOL and the Capsular Bag?

• How can I obtain a 2-dimensionsal cross-sectional image of the anterior segment of the eye?

Anterior segment OCT

Immersion B-scan ultrasound

Relationship Between the IOL and the Capsular Bag?

Relationship Between the IOL and the Capsular Bag?

Horizontal meridianIOL optic and posterior capsule

Relationship Between the IOL and the Capsular Bag?

Haptics located in 10-4 o’clock meridianIOL haptic at 10 o’clock proper position

Relationship Between the IOL and the Capsular Bag?

4 o’clock IOL haptic truncatedIOL optic shifted towards 4 o’clock

Ultrasound Biomicroscopy (UBM)

• 2-dimensional cross-sectional image of anterior segment

• Multiple meridians

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Dislocated IOL UBM

6:00 10:00

IOL optic IOL haptic in position

Dislocated IOL UBM

4:004:00

IOL haptic truncated

OCT Versus UBM

• 2-dimensional cross-sectional images of anterior segment

• Multiple meridians

• OCT provides more fine detail and magnified image

• OCT non-contact versus UBM contact (water-bath)

• OCT more useful to the anterior segment surgeon because easy to use

OCT Versus UBM

• MD or photographer performs UBM

• Photographer performs OCT

• OCT and UBM require communication between MD and photographer

Anatomic structure(s)

Location

Magnification

Imaging protocol

Anterior Segment OCT

Technical Specifications

Manufactuer Model Domain Scans/secAxial Res Trans Res

Scan Depth

Scan Length Lens

BioptigenEnvisu R2300 Spectral 32,000 <4 μm

21μm, 11μm, 7.5μm* 2.5mm 20mm Ext

HeidelbergSpectrali

s Spectral 40,000 3.9 μm 14 μm 1.9mm 16mm Ext

OptosOptos

OCT/SLOSpectral

27,000<6.0 μm 20 μm

2.0-2.3mm

6mmExt

Optovue iVue Spectral 26,000 5.0 μm 15 μm2-

2.3mm 12mm Ext

Optovue RT-Vue Spectral 26,000 5.0 μm 15 μm2-

2.3mm 12mm Ext

Zeiss Cirrus Spectral 27,000 5 μm 15 μm 2mm 4mm Int

Zeiss Visante Time 2,000 18 μm 60 μm 6mm 16mm Int

OCT Specifications Comparison

Not currently FDA approved with AS-OCT from the following manufactures:

Nidek, Optopol, Tomey, and Topcon (as of March 2012)

Time and Spectral Domain OCT Time and Spectral Domain OCT

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Anterior Segment Specifications

Specifications Visante Spectral

SLD Wavelength 1310 840-870

Optical Power < 6500 µW 750µW

The longer wavelength of light and stronger optical power allow TD technology to penetrate deeper into the angle.

The shorter wavelength of light and lower optical power make it possible for the SD technology to also image the retina

Anterior Segment SpecificationsSpecifications Visante Spectral

SLD Wavelength 1310 840-870

Scan Depth 3mm,6mm 1.9-2.3mm

Scan Length 10mm, 16mm

1-2,1-6*

Higher Wavelength allows for deeper scan depth and longer scan length

More scan depth is able to image cornea to lens

Longer scan length can image limbus to limbus. *Heidelberg is exception

Graphic modified from Zeiss graphic

6x16 3x10

2x6 2x1

Shorter scan length has better resolution

The following two slides show one individual wearing a +13.50 soft contact lens

Longer scan length gives

better overview

Importance of Scan Length

• DSEK– Limbus to Limbus Imaging is necessary to

ensure proper attachment of the donor tissue

• Scleral Contact Lens Fitting– Needed to view the entire lens in one image

• Glaucoma– Able to measure both angles from one image.

Slipped DSEK Comparison Longer vs Shorter Scan Length

Courtesy Team Doheny Eye

16mm 10mm

6mm6mm

Text

Scleral Contact Lens Glaucoma

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Why Do I Image the Cornea?• Analysis of new corneal transplantation

techniques

• Management of postop complications

• Document healing of surgical incisions

• Plan operations

• Management of corneal ulcers

• Evaluate extent of tumors of the ocular surface

• Measurements of the anterior segment

Fuchs’ Corneal Dystrophy

• Fuchs dystrophy

Inherited disease of corneal endothelium

Endothelium dysfunctional

Corneal edema

Vision decreases

• Guttae obscure endothelium

Specular microscopy

Corneal EndotheliumFunction

• Pumps H2O out of the cornea into the anterior chamber

• Keeps corneal stroma at 78% H2O

• Transparent at thickness 550 μ

• Pachymetry is a measurement of corneal thickness

• Gauges health of cornea

Corneal Edema

Hazy cornea Stomal and epithelial edema

Fuchs’ DystrophyTreatment

• Penetrating keratoplasy

• Full thickness recipient cornea removed

• Full thickness donor cornea sutured into place

• 360° full thickness corneal wound

• 1 year for visual rehabilitation

• Irregular healing of wound results in

variable visual results due to astigmatism

Penetrating Keratoplasty

Epithelial defect

Penetrating Keratoplasty

Irregular healing of full thickness incisionVisually disabling astigmatism

DSEK: Descemet’s Stripping Endothelial Keratoplasty

• Diseased endothelium and Descemt’s membrane removed (30 μ)

• Donor endothelium and stroma inserted (~150 μ)

• Small incision (5 mm)

• Rapid healing and visual rehabilitation in

30 to 60 days

OCT to Monitor Health of DSEK

• Position

• Attachment of graft to recipient

• Quality of interface

• Corneal thickness

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DSEK

1 D

1 W

1 M

1038 μ

687 μ

618 μ

DSEK 4 Weeks Post-op

Ultrasound pachymetry 549 μ

Ultrasound Pachymetry Incorrect

• Normal thickness 550 μ

• 30 μ endothelium and Descemet’s membrane removed

• 180 μ donor cornea implanted

• Pachymetry after DSEK should be at least 700 μ

DSEK 4 Weeks Postop Visante Flap Tool

Corneal thickness 769 μ

Detached DSEK 1 Day Postop

Anterior Segment OCT

• DESK attachment 360° would indicate primary donor failure

Require graft replacement

• DSEK detachment

Reattach graft with air

DSEK ReattachmentAir Injection

1 day postop 1 week postop

7 weeks postop 4.5 months postop

Malpositioned DSEK

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Malpositioned DSEK

180° meridian

90° meridian

Slipped inferiorly

Available Measurements

• Corneal thickness

• Anterior chamber depth

• Anterior chamber angle

• Incision

• Tumor

Automated Global Pachymetry

770 μ

Corneal Thickness

Corneal thickness 769 μ

Pachymetry Data Points

Global Pachymetry

– 16 line scans

– 2048 data points in one map

Pachmate Pachymetry

1 data point

Pachymetry Data Points

Global Pachymetry

– 16 line scans

– 2048 data points in one map

Pachmate Pachymetry

1 data point

Anterior Chamber Depth

Post-Op

5.16 mm3.61 mm

Pre-Op

Measuring Angles

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Measuring Angles

• AOD: angle-opening distance

• TIA: trabecular-iris angle

• TISA: trabecular-iris space area

Clear Corneal Incision Clear Corneal Incision

Descemet’s detachment Endothelial misalignment Epithelial misalignment

Endothelial gape Epithelial gape Lack of coaptation

Tumors / Cysts

Unable to use measurement features in Raw Mode

Must understand what is real and what is an artifact

Artifact on the Scan Artifacts

• Corneal Reflex

• Inverted Image (in Spectral Domain)

• Shadowing

• Image Averaging

• Algorithm Failure

– Pachymetry: Corneal surface lines

– Pachymetry: Lids

Corneal ReflexInverted Image

Spectral Domain Shadowing?

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Shadowing Image Averaging

Top: Non-averaged ScansBottom: Averaged Scans

Averaging

Enhanced High Res Cornea Mode

Measuring with Averaging

Enhanced High Res Cornea Mode

Dewarping

Enhanced Mode

Algorithm Failure Due to Lids

superior inferior

Algorithm Failure Due to LidsAlgorithm Failure

Due to Corneal Surface LinesAlgorithm Failure

Due to Corneal Surface Lines

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Algorithm FailureDue to Corneal Surface Lines

How Else Does Anterior Segment OCT Help Me With Patients?

Visualize Depth of Corneal Scar

DSEK with a scar

Visualize Depth of Corneal Scar

Excellent detail of cornea

Flattening of corneal surface over scar

Ocular Surface Tumors

• Does the tumor extend into the cornea, sclera, and anterior chamber angle?

• Plan operative procedure

Corneal and ConjunctivalIntraepithelial Neoplasia

Corneal and ConjunctivalIntaepithelial Neoplasia Infectious Keratitis

• Hazy cornea

• Difficult to see extent of corneal involvement

• Monitor response to medical therapy

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Fungal Corneal Ulcer Anterior Chamber Depth

• Important for IOL calculation

• Theoretical prediction formula: Haigis

• Required to predict the post-op position of the IOL

• Correct IOL power can be inserted

• 0.05 mm ACD error = 0.03 diopter IOL power error

Pre-op Phaco IOL CalculationAnterior Chamber Depth

IOLMaster Visante

4.10 mm

ACD difference = 1.8 mm = 1.08 diopters

Irregular Pupil Gonioscopy

Peripheral anterior synechiae Holes in iris

PASNormal ciliary body

OCT

UBM

Essential Iris Atrophy

Interesting Recent Cases

1 day postopLocalized corneal edema at incision

Anterior Segment OCTDetached Descemet’s Memebrane

923 µ

s

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2 Months PostopIrregular Posterior Cornea

2 Months PostopEndothelial Gape

710 µ

s

1 Day Postop DSEKCorneal Edema

Can you tell if the DSEK is attached??

Anterior Segment OCTDSEK Not Attached

2 Days After Air Injection

s

Anterior Segment OCTVisante

2011

2012

sm

Anterior Segment OCTHeidelberg

2012

sm

Fuchs’ DystrophyHeidelberg

15 degrees

20 degrees

Guttae more visible with high magnification

sm

21 Months Postop DSEKVisante vs Heidelberg

Opacities in interface

sm

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21 Months Postop DSEKHeidelberg

Opacities in interface

Avoid the corneal reflex

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Corneal Edema with Hydration

Etiology and Management?

CD: 1845

482µ

1 day post-op 1 month post-op s

541µ→525µ→534µ→581µ

Pellucid Marginal Corneal Degeneration

Center → Periphery

Keratoconus

408µ→382µ→420µ→482µCenter → Periphery

Thanks for your help!

UNC DoctorsBruce Baldwin, OD, Ph.DCraig Fowler, MDDavid Russell, MDGeorge Escaravage, MDGraham Lyles, MDIsaac Porter, MDJonathan Dutton, MDKenneth Cohen, MD

UNC PhotographersDebra Cantrell, COARona Lyn Esquejo-Leon,

CRA

PhotographersDoheny Eye Institute

Bruno Bertoni, CRA, OCT-CTamera Davis, CRA

Henry Ford Health Systems Alexis Smith, OCT-C, CRA

University of California- DavisEllen Redenbo, CRA, ROUBKarishma Chandra

University of Florida Eye Institute John Carpentier, CRA, OCT-C

Wills Eye InstituteSandor Ferenczy, CRASusan Proietta

BioptigenEric Buckland, Ph.DSunita Sayeram, MSJoseph Vance

HeidelbergTim Steffens

OptovueBill DillworthMark ThomasCarl Denis, CRA

ZeissGreg HoffmeyerRick TorneyTracy MooreGary Michalec, CRA, COACherri Ritter

Kenneth L. Cohen, MDSterling A. Barrett Distinguished Professor

Sarah Moyer, CRA, OCT-CDirector of Ophthalmic Imaging

smoyer@gmail.com

Kittner Eye Center, University of North Carolina Chapel Hill, NC