RTVue 100The Next Generation OCT

Principles 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 various depths with a reference ‘standard’

• Differences between the reflected light and the reference standard provide structural information in the form of an ‘A’ scan

Principles of OCT Technology•An A-scan is the intensity of reflected light at various retinal depths at a single retinal location

• Combining many A-scans produces a B-scan

A-scan A-scan

+ + . . . =

B-scanA-scans

Re

tina

l De

pth

Reflectance Intensity

Fourier 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 second)

• Broad-band light source provides high depth resolution (5 microns)

The Evolution of OCT Technology

• 65 x faster• 2 x resolution

Zeiss OCT 1 and 2, 1996

Zeiss Stratus 2002

OptoVue RTVue 2006

26,000

400

100

16 10 5

Speed(A-scansper sec)

Resolution (m)

Fourier domain OCT

Time domain OCT

Evolution of Commercial OCT

1996

2002

2006

OCT 1(Time Domain)

Stratus OCT(Time Domain)

RTVue(Fourier Domain)

Time Domain OCT

SLD

Lens

Detector

Data Acquisition

Processing

Combines light from reference with reflected

light from retina

Distance determines depth in A scan

Reference mirror moves back and forth

Scanning mirror directs SLD

beam on retina

Interferometer

Broadband Light Source

Creates A-scan 1 pixel

at a time

Final A-scan

Process repeated many times to create

B-scan

Slide courtesy of Dr. Yimin Wang, USC

Fourier Domain OCT

SLD

Spectrometer analyzes signal by

wavelength FFT

Grating splits signal by

wavelength

Broadband Light Source

Reference mirror stationary

Combines light from reference with reflected

light from retina

Interferometer

Spectral interferogram

Fourier transform converts signal to

typical A-scan

Entire A-scan created at a single timeSlide courtesy of Dr. Yimin Wang, USC

Process repeated many times to create

B-scan

Fourier 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 movements

Time 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 movements

512 A-scans in 1.28 sec

Motion artifact

Higher speed, higher definition and higher signal.

1024 A-scans in 0.04 sec

Small blood vessels

IS/OS

Choroidal vessels

Slide courtesy of Dr. David Huang, USC

Fourier Domain OCT

• High speed reduces eye motion artifacts present in time domain OCT

• High resolution provides precise detail, 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 scanning

B-scans provide high resolution detail

Retinal Layers with RTVue & Histology

ILMNFLGCLIPLINLOPLONLPR IS/OSRPEChoriocapillaris and choroid

Fovea ParafoveaTemporal Nasal

Macula thickness map reveals edema

RPE Elevation map reveals drusen & CNV

RPE Elevation map reveals CNV

Change Analysis for macula

Glaucoma Analysis

• RNFL Thickness Map

• Neural retinal rim

• Cup area

• RNFL TSNIT graph at 3.45 mm circle

Measuring the ganglion cellsInner retinal layer providesGanglion cell assessment:

• Axons = nerve fiber layer• Cell Body = ganglion cell layer• Dendrites = inner plexiform layer

Images courtesy of Dr. Ou Tan, USC

Ganglion cell layer in macula analyzed for glaucoma

Inner Retina Segmentation

Provides thickness of:• RNFL layer• Ganglion cell layer• Innerplexiform layer

Normal vs Glaucoma

Normal Glaucoma

CupRim

RNFL

Inner RetinaMacula Map

Retina Examples

Normal

Rod cone dystrophy

Images courtesy of Dr. Jennifer Lim, USC

Courtesy: Michael Turano, CRAColumbia University.

Cystoid Macula Edema

Courtesy: Michael Turano, CRAColumbia University.

horizontal vertical

Diabetic Retinopathy

Images courtesy of Dr. Tano, Osaka University

Central Retinal Vein Occlusion

Images courtesy of Dr. Tano, Osaka University

horizontalhorizontal verticalvertical

AMD-Classic CNV

Images courtesy of Dr. Tano, Osaka University

Idiopathic CNV

Images courtesy of Dr. Tano, Osaka University

horizontalhorizontal verticalvertical

Macula Hole

Images courtesy of Dr. Tano, Osaka University

Courtesy: Michael Turano, CRAColumbia University.

Diabetic Macula Edema with Epiretinal Membrane

Central Serous Chorioretinopathy with PED

early phase FA

56 year old Female

Sub-retinal fluid PED

Images courtesy of Dr. Tano, Osaka University

Operculum

Courtesy: Michael Turano, CRAColumbia University.

Stage 3 Full Thickness Macular Hole

Central Serous Chorioretinopathy

Images courtesy of Dr. Tano, Osaka University

Epiretinal Membrane

Images courtesy of Dr. Tano, Osaka University

Retinitis Pigmentosa

Images courtesy of Dr. Tano, Osaka University

Courtesy: Michael Turano, CRAColumbia University.

Vitreomacular Traction Syndrome with CME

Patient MB – Neovascular AMD

Fundus Photograph FA

Case courtesy of Dr. Nalin Mehta, Colorado Retina Center

Patient MB – Neovascular AMD

Fluid accumulation

CNVCase courtesy of Dr. Nalin Mehta, Colorado Retina Center

Patient MB – Neovascular AMDFull Retinal Thickness Map RPE Elevation Map

RPE elevation due to CNVLarge area of abnormally thick retina from intraretinal

fluid accumulation Case courtesy of Dr. Nalin Mehta, Colorado Retina Center

Patient WB – Neovascular AMD

Fundus Photograph FA

• 86 year old male

Case courtesy of Dr. Nalin Mehta, Colorado Retina Center

Patient WB – Neovascular AMD

CNV

Date: 1/10/07

3-D Evaluation reveals extent of CNV

Case courtesy of Dr. Nalin Mehta, Colorado Retina Center

Patient WB – Neovascular AMDFull Retinal Thickness Map RPE Elevation Map

RPE / choroid disruption identifies presence of CNV

Some abnormal thickening and thinning

Case courtesy of Dr. Nalin Mehta, Colorado Retina Center

Patient WB – Neovascular AMD

1/10/07

2/23/07

B-scan comparison Full retinal Thickness RPE Elevation

Treatment• 2/7 – Lucentis• 2/14 – PDT

Thinning of retina and improvement in RPE in response to treatment

Case courtesy of Dr. Nalin Mehta, Colorado Retina Center

Patient ED – Neovascular AMD• 84 year old male, initial exam 12/13/2006

FA shows leakage just superior to fovea

Full retinal thickness shows no thickening

RPE elevation map clearly shows area of CNV superior to fovea

FA Full retinal thickness map RPE elevation map

Case courtesy of Dr. Nalin Mehta, Colorado Retina Center

Patient ED – Neovascular AMD

Initial Exam:12/13/2006

Follow-up Exam:3/20/2007

RPE/Choroid shows some reduction in height, but overall retinal thickness increases due to intra-retinal fluid accumulation

Treatment1/17 – Macugen3/14 - Macugen

Case courtesy of Dr. Nalin Mehta, Colorado Retina Center

Patient ED – Neovascular AMD

Case courtesy of Dr. Nalin Mehta, Colorado Retina Center

Total Retinal Thickness increases RPE elevation decreases

Patient WW – AMD• 76 year old male.

Drusen

PEDs

Case courtesy of Dr. Nalin Mehta, Colorado Retina Center

Patient WW – AMD

Full Retinal Thickness Map RPE Elevation Map

Localized elevations reveal location of PED and Drusen

Full Retinal thickness map normal

Case courtesy of Dr. Nalin Mehta, Colorado Retina Center

Comparison of Stratus OCT to RTVue OCT

ComparisonRTVue Stratus• Fourier Domain OCT

• 26,000 A scans per second

• 5 µm depth resolution

• Retina Assessment• Dense Full Retinal Thickness map• RPE elevation map• 3-D macula scans

• Glaucoma Assessment• RNFL map• Inner Retinal Thickness map (Ganglion cell assessment -> axon+cell body+dendrites)• Optic disc

• RTVue is 65 times faster

• RTVue has twice the depth resolution

• Time Domain OCT

• 400 A scans per second

• 10 µm depth resolution

• Retina Assessment• Sparse retinal thickness map for retina (97% interpolated)

• Glaucoma Assessment• RNFL ring for glaucoma (TSNIT curve)

Comparison of Stratus OCT to RTVue OCTGlaucoma ComparisonRTVue Stratus

• Data Captured: 9510 A scans (pixels)• Time: 370 msec• Area covered: 4 mm diameter circle • RTVue has 97% more data

• RTVue is over 5 times faster

• Data Captured 256 A scans (pixels)• Time: 1.92 seconds• Area Covered: ring at 3.45 mm diameter

Provides •Cup Area• Rim Area• RNFL Map• TSNIT graph

Provides• TSNIT graph

• RTVue provides comprehensive glaucoma information

Plus, RTVue has exclusive Retinal Ganglion Cell layer assessment• Data Captured: 14,810 A scans (pixels)• Time: 570 msec• Area covered: 7 x 7 mm

Provides• Inner Retina Map• Ganglion cell assessment in macula

• No Comparison

• RTVue provides direct ganglion cell information

• Inner retina analysis:• RNFL• Ganglion cell body• Inner plexiform layer

RTVue can provide 3-D imaging of the optic disc and RNFL

• No Comparison

• Data Captured: 51,712 A scans (pixels)• Time: 2 seconds• Area covered: 4 x 4 mm

Provides•3 D map

• RTVue provides 3 D image of optic disc and parapapillary RNFL

Comparison of Stratus OCT to RTVue OCTRetina ComparisonRTVue Stratus

• Data Captured: 19,496 A scans (pixels)• Time: 780 msec• Area covered: 5 x 5 mm

• RTVue has 96% more data• RTVue is over 2.4 times faster

• Data Captured 768 A scans (pixels)• Time: 1.9 seconds• Area Covered: circle 6 mm diameter

Provides • Dense Retinal thickness map

Provides• Sparse Retinal thickness map• 97% interpolated between lines

• RTVue provides more data and a more detailed thickness map

RTVue has 3 D imaging of the macula• Data Captured: 51,7212 A scans (pixels)• Time: 2 seconds• Area covered: 4 x 4 mm

Provides• 3 D map of the macula

• No Comparison• RTVue provides 3-D

image of macula for a comprehensive review of B-scans over large area

Plus, RTVue has RPE elevation map for Drusen and CNV• Data Captured: 19,496 A scans (pixels)• Time: 780 msec• Area covered: 5 x 5 mm

Provides • RPE Elevation map

• RTVue RPE elevation map reveals location and extent of Drusen and CNV which is missed by retinal thickness maps

• No Comparison

RTVue Details• Scan Speed: 26,000 A scans per second• Depth Resolution: 5 microns• Transverse Resolution: 15 microns• Frame Rate: 256-4096 A-scans per frame• Scan Depth 2 mm – 2.3 mm• Scan length 2 mm – 12 mm• SLD wavelength: 840 +/- 10 nm• Focus Range: -15 D to +12 D• Retina scans: Glaucoma Scans

High res line scanHigh res cross scanMacula Map over 5 mm x 5 mm3-D macula scan

Nerve Head Map over 4 mm DiameterMacula Map over 7 mm x 7 mmRNFL 3.45 scan circle3-D Optic Disc

Scan Details: Line and CrossType # Ascans, # Bscans Scan Time Transv. Res

Line 1024 1 39 msec 5.9 µm line length: 6 mm (adj. 2-12mm)

Cross 1024 2 78 msec 5.9 µm line length: 6 mm (adj. 2-12mm)

HD Line 4096 1 156 msec 1.5 µm line length: 6 mm (adj. 2-12mm)

HD Cross 4096 2 312 msec 1.5 µm line length: 6 mm (adj. 2-12mm)

line

horizontal vert

ical

High density line

HD horizontal HD

ver

tica

l

Scan Details: 3-DType # Ascans, # Bscans Scan Time Transv. Res

3-D Macula 512 101 2 sec 7.8 µm size: 4x4 mm

3-D Disc 512 101 2 sec 7.8 µm size: 4x4 mm

Scan Details: MapsType # Ascans, # Bscans Scan Time Transv. Res

MM5 (Retina) 668 22 7.5 µm 400 12 total 780 msec 7.5 µm macula map size: 5x5 mm

NHM4 (Glaucoma) 452 12 7.5 µm587 & 775 6 total 390 msec 4.3-5.2 µm map size: 4 mm diameter circle

MM7 (Glaucoma) 467 1 15.0 µm 400 15 total 580 msec 17.5 µm macula map size: 7x7 mm