Understanding What Does Anterior Segment OCT Do? Anterior ... · technology to penetrate deeper...
Transcript of Understanding What Does Anterior Segment OCT Do? Anterior ... · technology to penetrate deeper...
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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
Kittner Eye Center, University of North Carolina Chapel Hill, NC