Structural examina.on: Imaging

Transcription

1 ManaMa: Glaucoma Structural examina.on: Imaging Luís Abegão Pinto, MD, PhD Department of Ophthalmology CHLC Lisbon Faculty of Medicine, Lisbon University 1

2 Structural changes Qualitative changes Quantitative changes Shape and thickness of neural rim Optic cup/disc size Nerve fibre layer evaluation Neural rim thickness Disc hemorrhages Nerve fiber layer thickness Structural changes: Imaging Confocal HRT Microscopy OpLcal Coherence OCT Tomography GDx Polarimetry GDx Polarimetry 2

3 GDx Principle based on the physical properties of the tissue to be studies (NFL) RNFL R RNFL retardation Detects earlier defects in NFL than HRT, but at cost of increasing false positives Ceiling effect in advanced glaucoma Br J Ophthalmol : GDx CORNEA Other structure in the eye with polarizing ability Correction for cornea polarization by two systems: 1. Variable Cornea compensator (VCC) 2. Enhanced Cornea Compensatior (ECC) GDx: Printout Normal Glaucoma The Fundus Image Useful for image quality 3

4 GDx: Printout Normal Glaucoma Thickness Map Presents RNFL thickness in color with thick regions in red and yellow and thin regions in blue and green GDx: Printout Normal Glaucoma Deviation Map Compares the thickness to a normative database and identifies the location and magnitude of RNFL loss GDx: Printout Normal Glaucoma TSNIT Graph Plots RNFL thickness around the optic disc 4

5 GDx: Printout Normal Glaucoma Parameters Color-coded if they fall outside the normal limits GDx: Printout Parameters and Nerve Fiber Indicator (NFI) Normal Borderline Abnormal GDx: limitations Dependent on the quality of the image Transparency of the media new baseline after cataract surgery Only RNFL thickness (no information about optic disc) Early detection balanced by a ceiling effect in advanced glaucoma 5

6 Concept of confocal microscopy Patented in 1957 Improvement of the image quality through analysis of a single confocal plane Use of a stenopeic pinhole Heidelberg ReLna Tomography (HRT) Each image: 384*384 points = Captures 3 blocks of 64 images 3D Reconstruction 64x Examination conditions Imaging angle width 15º Need for accurate fixation Collaboration of patient needed No need for pharmacological dilatation Disturbed lacrimal film disturbs imaging quality Heidelberg ReLna Tomography (HRT) Data provided 1 : Stereometrical parameters 2: Evaluation systems: - Moorfiels Regression Analysis (MRA) - Glaucoma Probability Score (GPS) 3: Progression analysis (TCA) 6

7 Heidelberg ReLna Tomography (HRT) Operator- dependent analysis: Drawing of contour line = subjeclve Reference plane: 50 microns below surface Defines: Excavation, Neural Rim Nerve fiber layer HRT: Moorfields Regression Analysis vs Glaucoma Probability Score Moorfields Regression Influenced by disc size Observator-dependent Glaucoma Probability Score Influenced by disc size Observator-Independent Better discrimination in early stages Ophthalmology 2007;114: Am J Ophthalmol 2008;145: HRT: Printout 7

8 Progression - Topographic Change Analysis (TCA) Comparison to baseline: Superpixel red/green Identifies progression earlier than functional exams or disc evaluation by specialists European Glaucoma Society A better reproducibility of progression evaluation Ophthalmology 2009;116:14 24 Invest Ophthalmol Vis Sci. 2009;50: Progression - Topographic Change Analysis (TCA) Trabeculectomy Trab HRT: limitations Collaboration of the patient needed (fixation) Dependent on the quality of the image Transparency of the media new baseline after cataract surgery Normative database : - 6D < x < +6D, disc size, age > 18 years Duration of the examination (1st exam up to 5 minutes) 8

9 Optical Coherent tomography: concept Probe Optical Coherent tomography: concept Time- Domain Spectral- Domain Super- luminescent diode Coupler Detector Optical Coherent tomography: concept Time- Domain Spectral- Domain Fast sweeping laser Coupler Detector 9

10 Optical Coherent tomography: concept Time- Domain Spectral- Domain Optical Coherent tomography: concept Type of OCT Commercial device Axial Resolu.on Time Domain Stratus (Carl Zeiss Meditec Inc, Dublin, CA, USA) 10µm Cirrus (Carl Zeiss Meditec Inc, Dublin, CA, USA) 5µm Spectralis (Heidelberg Engineering, Heidelberg, Germany) 3.9µm Spectral Domain RTVue (Optovue Inc, Fremont, CA, USA) 5µm OCT SLO (Optos plc, Dunfermline, UK) <6µm Copernicus (Optopol technology SA, Zawiercie, PL) 3µm 3D- OCT 2000 (Topcon Medical Systems, Oakland, NJ, USA) RS (Nidek Co., LTD., Aichi, Japan) 5-6µm 3-4µm OCT: optic disc anatomy Spectral domain: Bruch s membrane opening Time Domain: RPE interface Influenced by disc size Arbitrary rim calculalon (150µm above interface) IOVS 2012; 53:

11 OCT: printout Optic disc parameters RNFL Thickness RNFL Deviation map Tomographs RNFL thickness by Quadrants and clock hours OCT: printout RNFL Assimetry AddiLonal solware analysis: Assimetry between eyes RNFL progression RNFL Progression Color- coded Borderline Outside normal limits Spectral OCT outside the box Additional measurements Lamina cribosa Relevant to glaucoma pathogenesis but never before clinically assessed Spectral OCT with enhanced depth imaging measures lamina thickness Am J Ophthalmol 2011;152:

12 Spectral OCT outside the box Additional measurements Macular thickness Spectral Domain OCT allows Ganglion Cell Complex measurements Ganglion cell complex may be important in structural assessment in early glaucoma Ganglion cell complex thickness patterns may be different in NTG vs POAG J Glaucoma Apr-May;20(4):252-9 J Glaucoma Jun 22. [Epub ahead of print] Spectral OCT outside the box Additional measurements Anterior Segment New Software Qualitative imaging Non invasive angle assessment (iris plateau) Am J Ophthalmol Aug;156(2): e2. 12

13 Imaging techniques: Global Comparison GDx HRT OCT RNFL Disc morphology Macular GC Deeper structures (lamina cribrosa, choroid) Anterior Segment Confocal microscopy* Qualitative assessment Thank You 13