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Understanding Anterior Segment OCT Clinical Applications of Anterior Segment OCT • • • • • • • Sarah Moyer, CRA, OCT-C Director of Ophthalmic Imaging Kenneth L. Cohen, MD Sterling A. Barrett Distinguished Professor Kittner Eye Center Department of Ophthalmology University of North Carolina at Chapel Hill School of Medicine What Does Anterior Segment OCT Do? 2-dimensional cross section image of the anterior segment Anatomy Vendors Clinical use of AS-OCT Technical aspects Measurements Artifacts Recent Cases No financial interest Anterior Segment Anatomy Limbus Iris Cornea Cornea Corneal Anatomy Air / tear interface Anterior Chamber Tear Film Epithelium Stroma Endothelium DSEK with fold Pupil Bullous Keratopathy Angle Lens Hydrops Kerataconus Ciliary Body Iris / Angle Lens Iris Cyst Imaging Lens Conjunctiva / Sclera Anterior Chamber IOL High Pressure Pterygium Scleral Buckle Iris Cyst Open Angle Capsular Block Slipped Lens Conjunctival Lesion Closed Angle Iris Neoplasm Courtesy Team Doheny Eye 1 Anterior Segment OCT Vendors Bioptigen Heidelberg Optos Optovue Topcon Zeiss Bioptigen Heidelberg Spectralis Handheld OCT Spectralis with Lens Optos OCT/SLO RT-Vue with CAM iVue SL Scan-1 3D OCT-2000 Visante and Cirrus Courtesy of Sunita Sayeram and Joseph Vance Optos OCT/SLO Courtesy of John Carpentier Courtesy of Tim Steffens Optovue RT-Vue with CAM Synechia Courtesy Team Doheny Eye AC Tube Courtesy Ellen Redenbo and Mark Thomas Courtesy of Bruno Bertoni, CRA, OCT-C and Tamera Schoenholz, CRA Corneal Scar Courtesy Team Doheny Eye Courtesy of Optos Courtesy Optovue Courtesy of Optovue Topcon SL Scan-1 K-Pro Courtesy Mark Thomas and Ellen Redenbo Topcon 3D OCT-2000 Topcon 3D OCT-2000 Photo Credit: Media Resources Centre University Hospitals of Wales Cardiff UK Thanks Chris Tetley! Not currently available in the US Not currently available in the US 2 Closed Angle Glaucoma Cirrus 512x128 cube scan. 4mmx 4mm Internal Optics Software Upgrade needed Two scan patterns Zeiss Stratus Fuchs’ Dystrophy 5-line raster 3 mm length, adjustable rotation and spacing Filtering Tube Filtering Bleb DSEK Images courtesy of Martha Leen, M.D. & Paul Kremer M.D. Achieve Eye and Laser Specialists, Silverdale, WA Zeiss Stratus Not FDA approved Zeiss Visante Are you getting reimbursed for your AS-OCT? Courtesy of Zeiss Courtesy of Alexis Cullen, OCT-C, CRA Billing 1 Week After Phaco and 1-Piece Posterior Chamber IOL • 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 3 Dislocated IOL IOL 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? Relationship Between the IOL and the Capsular Bag? Relationship Between the IOL and the Capsular Bag? • How can I obtain a 2-dimensionsal crosssectional image of the anterior segment of the eye? Anterior segment OCT Immersion B-scan ultrasound Horizontal meridian IOL optic and posterior capsule Relationship Between the IOL and the Capsular Bag? Relationship Between the IOL and the Capsular Bag? Ultrasound Biomicroscopy (UBM) • 2-dimensional cross-sectional image of anterior segment • Multiple meridians Haptics located in 10-4 o’clock meridian IOL haptic at 10 o’clock proper position 4 o’clock IOL haptic truncated IOL optic shifted towards 4 o’clock 4 Dislocated IOL UBM 6:00 Dislocated IOL UBM 10:00 IOL optic 4:00 4:00 IOL haptic truncated IOL haptic in position 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 OCT Specifications Comparison Manufactuer Model Bioptigen Envisu R2300 Spectral Heidelberg Spectrali s Spectral Optos Optos OCT/SLO Spectral iVue Spectral Optovue Domain Time and Spectral Domain OCT Axial Res Trans Res Scan Depth Scan Length 32,000 <4 μm 21μm, 11μm, 7.5μm* 2.5mm 20mm Ext 40,000 3.9 μm 14 μm 1.9mm 16mm Ext Scans/sec 27,000 <6.0 μm 20 μm 2.02.3mm 26,000 5.0 μm 15 μm 22.3mm 15 μm 22.3mm 6mm Lens Ext 12mm Ext Optovue RT-Vue Spectral 26,000 12mm Ext Zeiss Zeiss Cirrus Spectral 27,000 5 μm 15 μm 2mm 4mm Int Visante Time 2,000 18 μm 60 μm 6mm 16mm Int 5.0 μm Time and Spectral Domain OCT Not currently FDA approved with AS-OCT from the following manufactures: Nidek, Optopol, Tomey, and Topcon (as of March 2012) 5 Anterior Segment Specifications Specifications Visante Spectral SLD Wavelength 1310 840-870 Optical Power < 6500 µW 750µW Shorter scan length has better resolution Anterior Segment Specifications Specifications Visante Spectral SLD Wavelength 1310 840-870 Higher Wavelength allows for deeper scan depth and longer scan length Scan Depth 3mm,6mm 1.9-2.3mm More scan depth is able to image cornea to lens Scan Length 10mm, 16mm 1-2,1-6* Longer scan length can image limbus to limbus. *Heidelberg is exception 6x16 3x10 Graphic modified from Zeiss graphic 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 2x6 2x1 Importance of Scan Length • DSEK Longer scan length gives better overview The following two slides show one individual wearing a +13.50 soft contact lens Slipped DSEK Comparison Longer vs Shorter Scan Length 16mm 10mm 6mm 6mm – 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. Courtesy Team Doheny Eye Scleral Contact Lens Glaucoma Text 6 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 dystrophy Inherited disease of corneal endothelium Endothelium dysfunctional Corneal edema Vision decreases • Guttae obscure endothelium Specular microscopy • • • • • • Stomal and epithelial edema Penetrating Keratoplasty Irregular healing of full thickness incision Visually disabling astigmatism • 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 Fuchs’ Dystrophy Treatment Corneal Edema Hazy cornea Corneal Endothelium Function Fuchs’ Corneal Dystrophy Penetrating Keratoplasty 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 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 Epithelial defect OCT to Monitor Health of DSEK • • • • Position Attachment of graft to recipient Quality of interface Corneal thickness 7 DSEK DSEK 4 Weeks Post-op 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 1D 1038 μ 1W 618 μ 1M 687 μ DSEK 4 Weeks Postop Ultrasound pachymetry 549 μ Visante Flap Tool Detached DSEK 1 Day Postop Corneal thickness 769 μ Anterior Segment OCT • DESK attachment 360° would indicate primary donor failure Require graft replacement • DSEK detachment Reattach graft with air DSEK Reattachment Air Injection 1 day postop 7 weeks postop Malpositioned DSEK 1 week postop 4.5 months postop 8 Malpositioned DSEK Available Measurements • • • • • 180° meridian Corneal thickness Anterior chamber depth Anterior chamber angle Incision Tumor 90° meridian Slipped inferiorly Automated Global Pachymetry Corneal Thickness Pachymetry Data Points Global Pachymetry – 16 line scans – 2048 data points in one map Pachmate Pachymetry 1 data point 770 μ Corneal thickness 769 μ Pachymetry Data Points Global Pachymetry – 16 line scans Anterior Chamber Depth Pre-Op Measuring Angles Post-Op – 2048 data points in one map Pachmate Pachymetry 1 data point 3.61 mm 5.16 mm 9 Measuring Angles Clear Corneal Incision Clear Corneal Incision • AOD: angle-opening distance • TIA: trabecular-iris angle • TISA: trabecular-iris space area Descemet’s detachment Endothelial gape Tumors / Cysts Artifact on the Scan Must understand what is real and what is an artifact Endothelial misalignment Epithelial misalignment Epithelial gape Lack of coaptation Artifacts • • • • • Corneal Reflex Inverted Image (in Spectral Domain) Shadowing Image Averaging Algorithm Failure – Pachymetry: Corneal surface lines – Pachymetry: Lids Unable to use measurement features in Raw Mode Corneal Reflex Inverted Image Spectral Domain Shadowing? 10 Shadowing Image Averaging Averaging Enhanced High Res Cornea Mode Top: Non-averaged Scans Bottom: Averaged Scans Measuring with Averaging Dewarping Enhanced High Res Cornea Mode Enhanced Mode Algorithm Failure Due to Lids Algorithm Failure Due to Corneal Surface Lines Algorithm Failure Due to Lids superior inferior Algorithm Failure Due to Corneal Surface Lines 11 Algorithm Failure Due to Corneal Surface Lines How Else Does Anterior Segment OCT Help Me With Patients? Visualize Depth of Corneal Scar Visualize Depth of Corneal Scar Flattening of corneal surface over scar DSEK with a scar Corneal and Conjunctival Intraepithelial Neoplasia Ocular Surface Tumors • Does the tumor extend into the cornea, sclera, and anterior chamber angle? • Plan operative procedure Excellent detail of cornea Corneal and Conjunctival Intaepithelial Neoplasia Infectious Keratitis • Hazy cornea • Difficult to see extent of corneal involvement • Monitor response to medical therapy 12 Fungal Corneal Ulcer Anterior Chamber Depth Pre-op Phaco IOL Calculation 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 IOLMaster Visante 4.10 mm ACD difference = 1.8 mm = 1.08 diopters Irregular Pupil Essential Iris Atrophy Gonioscopy OCT PAS Normal ciliary body UBM Peripheral anterior synechiae Holes in iris Interesting Recent Cases 1 day postop Localized corneal edema at incision Anterior Segment OCT Detached Descemet’s Memebrane 923 µ s 13 2 Months Postop Endothelial Gape 2 Months Postop Irregular Posterior Cornea 1 Day Postop DSEK Corneal Edema 710 µ Can you tell if the DSEK is attached?? s Anterior Segment OCT DSEK Not Attached Anterior Segment OCT Visante 2 Days After Air Injection 2012 2011 s Anterior Segment OCT Heidelberg 21 Months Postop DSEK Visante vs Heidelberg Fuchs’ Dystrophy Heidelberg 2012 sm 15 degrees Guttae more visible with high magnification 20 degrees Opacities in interface sm sm sm 14 21 Months Postop DSEK Heidelberg Corneal Edema with Hydration 482µ CD: 1845 Avoid the corneal reflex Etiology and Management? Opacities in interface sm Pellucid Marginal Corneal Degeneration Keratoconus 1 day post-op UNC Photographers Debra Cantrell, COA Rona Lyn Esquejo-Leon, CRA Center → Periphery Kenneth L. Cohen, MD Sterling A. Barrett Distinguished Professor s Thanks for your help! UNC Doctors Bruce Baldwin, OD, Ph.D Craig Fowler, MD David Russell, MD George Escaravage, MD Graham Lyles, MD Isaac Porter, MD Jonathan Dutton, MD Kenneth Cohen, MD 541µ→525µ→534µ→581µ 1 month post-op Photographers Doheny Eye Institute Bruno Bertoni, CRA, OCT-C Tamera Davis, CRA Henry Ford Health Systems Alexis Smith, OCT-C, CRA University of California- Davis Ellen Redenbo, CRA, ROUB Karishma Chandra University of Florida Eye Institute John Carpentier, CRA, OCT-C Wills Eye Institute Sandor Ferenczy, CRA Susan Proietta Bioptigen Eric Buckland, Ph.D Sunita Sayeram, MS Joseph Vance Heidelberg Tim Steffens Optovue Bill Dillworth Mark Thomas Carl Denis, CRA Zeiss Greg Hoffmeyer Rick Torney Tracy Moore Gary Michalec, CRA, COA Cherri Ritter 408µ→382µ→420µ→482µ Center → Periphery Sarah Moyer, CRA, OCT-C Director of Ophthalmic Imaging [email protected] Kittner Eye Center, University of North Carolina Chapel Hill, NC 15
