Point-to-point correlations can also be established with fundus photography, fluorescein angiography, and ICG angiography images. However, each machine has its own specific characteristics.

The following pages were written with the help of manu-facturers to more clearly define the advantages and disad-vantages of each machine.

14

Appendix

Commercially Available

Spectral-Domain OCT Equipment

Since the initial development of Spectral-Domain OCT, anumber of companies now manufacture equipment basedon this technology for use by ophthalmologists: cliniciansand scientists.

Each of these machines offers all of the advantages of Spectral-Domain OCT: rapid acquisition, high resolu-tion, capability of 3D reconstruction.

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SLO ICG

SLO IR

SLO FA

14

Spectralis™ HRA-OCT

Heidelberg Engineering / SanoTek

▬ Scan speed: 40,000 A-scans/second.▬ Minimum pupil diameter: 2 mm.▬ Internal and external fixation targets.

▬ Focus Range: -24.00 to +40.00 D.

▬ Scanning field: 30° for OCT - 57° for angiography.

Main technical characteristics of OCT and HRA-OCT4 light sources:

Use Type of laser Wavelength

Fluorescein angiography and Red-free Sapphire laser 488nm (blue)Sapphire laser

SLO-ICG angiography Laser diode 785nm (near infrared)Laser diode

Infrared Laser diode 820nm (infrared)Laser diode

OCT Superluminescent diode 880nm (infrared)Superluminescent diode

OCT resolution Axial Transverse

3.8 μ 14 μ

Unique functions:

▬ High acquisition speed: 40,000 scans/second.Avoids artifacts from microsaccades and increases image definition.

▬ Noise reduction technology (Heidelberg Noise Reduc-tion Technology™).Allows visualization of fine structures.

▬ Automatic real-time image averaging system (ART or Automatic Real Time).

▬ Eye-tracking (TruTrack™ Technology and Tracking La-ser Tomography™):Tracks eye movements,Maintains scan position on the retina during the ex-amination,Automatically repositions scan at the same location as a previous examination.

▬ Reference image: Infrared, high quality angiography (SLO), autofluorescence.

▬ Composite image: real-time and automated.

Retina

▬ Retinal thickness mapping (maps, color scales, ETDRS target, segmentation)

▬ 3D modeling: various sections, multiframe movie,single frame.

Disc region

▬ Optic disc ring analysis program (ultrarapid circular scans).

▬ Comparison to a normative database.▬ Analysis of asymmetry between the two eyes.

Upgradeable

▬ Glaucoma module in the final stages of development.

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Heidelberg Engineering / SanoTek

Color-coded retinal thickness mapping

Follow-up of response to treatment and enlarged images

3D modeling, multiframe movie,

single frame

Glaucoma module (in final stages of development)

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CONNECTING VISIONSTOPCON 3D OCT

3D OCT-1000

▬ Optical Coherence Tomography (OCT), using a Spectral or Fourier domain system connected, for the first time, to a non-mydriatic fun-dus camera.

▬ Simple and rapid acquisition, both for patients side and photogra-phers, allowing the ophthalmologist to capture and analyze a selec-tion of OCT sections and merge them with the color fundus image.

▬ Characteristics:

Wavelength: 840 nmHorizontal resolution: ≤ 20 μmLongitudinal resolution: 5 μm

▬ Patient positioning:

The patient is positioned on a motorized chinrest and looks at a tar-get that can be adjusted according to the level of the patient’s vision.

▬ Photographer manipulations

They are simple, either manual or automatic depending on the set-ting. In automatic mode, once the patient has been installed, anAUTO Z key is activated, and the apparatus automatically detectsthe position of the OCT section. A quality score from 0 to 100 is dis-played.

Quantification and thickness measurements:

After scanning the retinal zone, the software calculates the thicknesses of the OCT zone and displays them as a chart orEDTRS scale, providing pachymetric quantification of the various layers of the retina, including optical fibers. This informa-tion can be compared with the normative database.

▬ The color image remains the reference image to compare examinations taken at different times. The B-Scan is always positioned on the same location as the color image and is independent of the patient’s fixation point.

▬ The color image can be replaced by another image (fluorescein angiography, ICG angiography, etc.)▬ A database network can be created with multiple viewing stations to allow analysis at other locations.

Color images:

▬ This color image is obtained with a set of alignment targets and automatic flash.

▬ With an angle of 45° through a 4 mm pupil, it covers the posterior pole, optic disc, and macula.

▬ Various imaging enhancements can be done, such as separation of green, red and blue light, area measurements, and enlarged views.

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CONNECTING VISIONSTOPCON 3D OCT

OCT SCANS

▬ OCT scans are acquired before acquisition of color fundus images.▬ The software provides a large choice of scan areas (3 mm x 3 mm - 4.5 mm x 4.5 mm - 6 mm x 6 mm - 8.2 mm x 3 mm),

scan number (1 to 128),r scan resolution (512 points to 4,096 points), scan interval, and allows overlapping of the samescan (2 – 16 passages).

3D IMAGING▬ A 3D image can be obtained by reconstituting the series of scans over a zone of 6 mm x 6 mm or a zone of 8.2 mm x 3

mm. Horizontal, vertical, or oblique examinations are all possible in this 3D image.▬ The various layers can be easily studied. They are pre-identified with computer analysis (nerve fiber layer - pigment

epithelium).▬ The 3D reconstitution of all B-scans allows various applications, such as examination of the vitreoretinal interface and

ensuring that the intended area is visualized. ▬ This technique avoids the need for the patient to be present once the examination has been completed.▬ Searching capabilities:

Once the examination has been completed, the user can, with the on-screen display, review the automatic analyses (reg-istration – thickness measurements, etc.)Previous examinations are accessible in the patient list as images, allowing a rapid overview of all examinations: 3D -RASTER, etc.

▬ Able to export movies for 3D presentations.

Color image of the

optic disc

OCT scan

of the optic disc

▬ Glaucoma

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The Most Comprehensive OCT

Technical specifications

Scanner

OCT image 26,000 A-scan/second

Frame rate 256 to 4096A-scan/frame

Depth resolution (in tissue) 5.0 μm

Transverse resolution 15 μm

Scan range Depth: 2- 2.3 mmTransverse: 2 mm to 12 mm

Wavelength 840 ± 10 nm

Exposure power 750 μm

Fundus imager

Field of view 32° (H) x 23° (V)

Illumination Near IR

Type of camera IR

Minimum pupil diameter 2.0 mm

Patient interface

Working distance 22 mm

Motorized focus range -15 to +12 D

▬ The RTVue provides high-resolution imaging of the retina layers, with detail and precision.

▬ A range of scan patterns is available to fit theimaging needs of a retina practice.

▬ These patterns are designed to take advantage of the speed and resolution offered by Fourier-domain OCT technology.

▬ The Line, Cross Line, and Grid Line scans a high de-tailed slice through the targeted area of the fundus.

▬ The averaging function provides noise reduction to en-hance the overall image and increase detail.

▬ All scan presentations are user selectable for Grayscaleor Color, either as the default or at any time duringviewing.

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The Most Comprehensive OCT

EMM5 scan (5 mm Macular Map)

▬ Detailed retinal mapping (23,768 data points) in a 5 mm x 5 mm area of the macula. A dense grid of 42 scans allows reconstruction of the map.

▬ Thickness topographies available for the total retina, inner retina, outer retina, and also for an retinal pigment epithe-lium detachment.

▬ Averages per quadrant, thicknesses and volumes for each retinal layer.Localization of the lesion is facilitated by the high-contrast SLO reconstruction.

▬ For more reliable comparison of examinations over time, the measuring algorithm identifies blood vessels to registerexaminations from one visit to the next.

3D Macular scan

▬ More than 54,000 A-scans are used for the 3D display and high-contrast SLO reconstruction.▬ Overview of the 3D image and viewing from multiple angles provide a maximum of options that can be customized.▬ The creation of short full-screen video sequences provides a teaching tool for patient information.▬ The 3D C-scan option using summation of C-scans allows visualization of the deep layers of the retina and choroid.

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OCT/SLO Imaging

Spectral OCT/SLO is an imaging system which combines:▬ Optical Coherence Tomography

▬ and Scanning Laser Ophthalmoscope (SLO),

designed to:▬ image the retina, choroidal, and the vitreo-retinal inter-

face▬ provide a confocal fundus image, which is linked to the

OCT B-Scan image of the retina.

Spectral OCT/SLO –Ophthalmic Technologies, Inc.

(OTI, Toronto, ON, CANADA)

Spectral OCT/SLO is a versatile system which can be used in a wide range of clinical applications.

RETINARetinal imaging

Due to utilization of spectral technology, the OTI system generates high-resolution images in a fraction of the time requiredby temporal-domain systems.Imaging with the Spectral OCT/SLO generates an image of such high resolution that the different layers of the inner retina are clearly seen. Subtle abnormalities may be detected sooner, allowing earlier intervention.

The OTI Spectral OCT/SLO provides an axial resolution of 4-6 μm with a scan rate of up to 27,000 A-scans per second. The shorter examination time reduces patient movement artifacts and makes the examination much easier for the patient andthe operator, especially in patients with low vision, small pupils, and opaque media.The OTI system provides a wide range of B-scan options: linear scan, radial scan, retinal scanning, graphic retinal thick-ness mapping, and various visualization modes such as grayscale, color, side-by-side visualization with the SLO image, and vitreous enhancement.

REAL-TIME REGISTRATION

Spectral OCT/SLO acquires OCT and SLO images simultaneously through a single optical system using the same lightsource.This allows direct correlation between the characteristics of the retinal surface on the SLO image and the internal charac-teristics of the retina visualized on the OCT image, providing precise real-time registration and orientation.

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Remove Vitreous Hide RNFL Hide Retina

Spectral OCT/SLO –Ophthalmic Technologies, Inc.

(OTI, Toronto, ON, CANADA)

3D TOMOGRAPHY

3D TOMOGRAPHY

SLO allows exact localization of the OCT topographic mapping by using a vascular pattern.

Retinal thickness is visualized in the form of a 8 x 8 grid, a 5 x 5 grid or in as zones. With SLO, the exact localization of the topographic mapping is determined by using information contained in the patient’s vascular pattern. Topographic mapping is obtained from a sequence of parallel B-scans, captured in TV scanning mode in 1 or 2 seconds. Sections can be extracted to demonstrate internal structures under the surface of the map.Topographic maps can be visualized in the form 3D topography or 3D tomography.

Comparison and topography subtraction

Microperimetry on the OTI Spectral OCT/SLO

▬ The SLO module of the OTI apparatus allows integration of microperimetry in the Spectral OCT/SLO. This capacity to perform a functional examination of the retina is specific and unique to the OTI Spectral OCT/SLO.

▬ The results are mapped on the SLO image of the fundus and can also be overlaid onto the retinal thickness map toestablish the link between retinal function and thickness in specific points of the retina.

▬ If the patient uses eccentric fixation, the system tracks the position of fixation, allowing continuation of the examinationrather than useless repetition of stimuli when the patient’s eye moves.

GLAUCOMA 3D topography / tomography optic nerve head analysis

The RNFL program acquires a circular OCT with a 3.4 mm diameter around the Optic Disc to capture Retinal Nerve Fiber Layer Thickness and its ratio to normative values.

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Cirrus™ HD-OCT-Carl Zeiss Meditec

Spectral-Domain OCT

Stratus Time-DomainOCT

Advantages of Spectral-Domain OCT

Light source 840 nm 820 nm High resolution820 nm840 nm 820 nm

Detector Spectrometer Unique detector Faster acquisitionUnique detectorSpectrometer Unique detector

Axial resolution 5-7 μm 10 μm5-7 μmBetter visualization of retinal layers

Transverse resolution 10 - 20 μm 20 μm10 - 20 μm

Number of A-scans per B-scan 4,000 - 8,000 512 Better visualization of lesions5124,000 - 8,000 512

A-scan depth 2 mm 2 mm Slight improvement of light penetration2 mm2 mm 2 mm

Number of A-scans per second 18,000 – 40,000 400 Better registration, 3D analysis40018,000 – 40,000 400

Main technical characteristics

▬ Light source: superluminescent diode (SLD), 840 nm▬ Pupil diameter: Minimum: l 2.5 mm / Optimum: 3 mm▬ Scan speed: 27,000 A-scans per second▬ Field of view: 36° x 30°▬ Axial resolution: 5 μm in tissue▬ Transverse resolution: 20 μm in tissue▬ Fundus imaging

Light source: superluminescent diode (SLD), 750 nmLive imaging during scanning

Internal and external fixation Focus adjustment range: -20 to +20 D▬ Retinal imaging

Retinal thickness mapping3D retinal mapping3D mapping of certain retinal layers

Carl Zeiss Meditec presents the advantages of the Cirrus™ HD-OCT as:

▬ High definition - High resolution▬ Easy image capture

▬ Compact▬ Ergonomic

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Cirrus™ HD-OCT-Carl Zeiss Meditec

The yellow square on the fundus image represents the limits of the cube analyzed (6 mm x 6 mm)

Precise localization of raster lines visible on the fundus image

)Segmentation of the ILM and ddnd nddd RPE RRRRRRR (3D)Segmentation of the ILM and RPE (3D)

Segmentation of the ILM and RPE (3D)Segmentation of the ILM and ndddnd nnndd RPE RRRRR (3DSegmentation of the ILM and RPE (3D)

Segmentation of the ILM and RPE (3D)

LSLO fundus image with overlay on retinal thickness maps

Retinal fiber thickness measurements

Normative database for glaucoma

Detailed optic nerve head analysis