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1、RTVue 100 The Next Generation OCTPrinciples of OCT Technology Optical Coherence Tomography (OCT) uses a principle called low coherence interferometry to derive depth information of various retinal structures This is performed by comparing the time difference in reflected light from the retina at var
2、ious depths with a reference standard Differences between the reflected light and the reference standard provide structural information in the form of an A scanPrinciples of OCT TechnologyAn A-scan is the intensity of reflected light at various retinal depths at a single retinal location Combining m
3、any A-scans produces a B-scanA-scanA-scan+ . . . =B-scanA-scansRetinal DepthReflectance IntensityFourier Domain OCT RTVue 100 Optical Coherence Tomography (OCT) provides cross sectional imaging of the retina Spectrometry and Fourier Domain methods allow high speed data capture (26,000 A scans per se
4、cond) Broad-band light source provides high depth resolution (5 microns)The Evolution of OCT Technology 65 x faster 2 x resolutionZeiss OCT 1 and 2, 1996 Zeiss Stratus 2002OptoVue RTVue 2006 26,00040010016105Speed (A-scans per sec)Resolution (mm)Fourier domain OCTTime domain OCTEvolution of Commerci
5、al OCT199620022006OCT 1 (Time Domain)Stratus OCT (Time Domain)RTVue (Fourier Domain)Time Domain OCTSLDLensDetectorData AcquisitionProcessingCombines light from reference with reflected light from retinaDistance determines depth in A scanReference mirror moves back and forthScanning mirror directs SL
6、D beam on retinaInterferometerBroadband Light SourceCreates A-scan 1 pixel at a timeFinal A-scanProcess repeated many times to create B-scanSlide courtesy of Dr. Yimin Wang, USCFourier Domain OCTSLDSpectrometer analyzes signal by wavelengthFFTGrating splits signal by wavelengthBroadband Light Source
7、Reference mirror stationaryCombines light from reference with reflected light from retinaInterferometerSpectral interferogramFourier transform converts signal to typical A-scanEntire A-scan created at a single timeSlide courtesy of Dr. Yimin Wang, USCProcess repeated many times to create B-scanFouri
8、er Domain OCT Simultaneous Entire A-scan at once 2048 pixels per A scan 26,000 A scans per second 1024 A-scans in 0.04 sec Faster than eye movementsTime Domain OCT Sequential 1 pixel at a time 1024 pixels per A-scan 400 A scans per second 512 A-scans in 1.28 sec Slower than eye movements512 A-scans
9、in 1.28 secMotion artifactHigher speed, higher definition and higher signal.1024 A-scans in 0.04 secSmall blood vesselsIS/OSChoroidal vesselsSlide courtesy of Dr. David Huang, USCFourier Domain OCT High speed reduces eye motion artifacts present in time domain OCT High resolution provides precise de
10、tail, allows more structures to be seen Larger scanning areas allow data rich maps & accurate registration for change analysis 3-D scanning improves clinical utility High Speed allows 3-D scanningB-scans provide high resolution detailRetinal Layers with RTVue & HistologyILM NFL GCL IPL INL OPL ONL P
11、R IS/OS RPE Choriocapillaris and choroidFoveaParafoveaTemporalNasalMacula thickness map reveals edemaRPE Elevation map reveals drusen & CNVRPE Elevation map reveals CNVChange Analysis for maculaGlaucoma Analysis RNFL Thickness Map Neural retinal rim Cup area RNFL TSNIT graph at 3.45 mm circleMeasuri
12、ng the ganglion cellsInner retinal layer provides Ganglion cell assessment: Axons = nerve fiber layer Cell Body = ganglion cell layer Dendrites = inner plexiform layerImages courtesy of Dr. Ou Tan, USCGanglion cell layer in macula analyzed for glaucomaInner Retina SegmentationProvides thickness of:
13、RNFL layer Ganglion cell layer Innerplexiform layerNormal vs GlaucomaNormalGlaucomaCup Rim RNFLInner Retina Macula MapRetina ExamplesNormalRod cone dystrophyImages courtesy of Dr. Jennifer Lim, USCCourtesy: Michael Turano, CRA Columbia University.Cystoid Macula EdemaCourtesy: Michael Turano, CRA Col
14、umbia University.horizontalverticalDiabetic RetinopathyImages courtesy of Dr. Tano, Osaka UniversityCentral Retinal Vein OcclusionImages courtesy of Dr. Tano, Osaka UniversityhorizontalhorizontalverticalverticalAMD-Classic CNVImages courtesy of Dr. Tano, Osaka UniversityIdiopathic CNVImages courtesy
15、 of Dr. Tano, Osaka UniversityhorizontalhorizontalverticalverticalMacula HoleImages courtesy of Dr. Tano, Osaka UniversityCourtesy: Michael Turano, CRA Columbia University.Diabetic Macula Edema with Epiretinal MembraneCentral Serous Chorioretinopathy with PEDearly phase FA56 year old FemaleSub-retin
16、al fluidPEDImages courtesy of Dr. Tano, Osaka UniversityOperculumCourtesy: Michael Turano, CRA Columbia University.Stage 3 Full Thickness Macular HoleCentral Serous ChorioretinopathyImages courtesy of Dr. Tano, Osaka UniversityEpiretinal MembraneImages courtesy of Dr. Tano, Osaka UniversityRetinitis PigmentosaImages courtesy of Dr. Tano, Osaka UniversityCourtesy: Michael T
