APAO 2016 Heidelberg Engineering Special Report

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OCT2 Module

Next generation OCT module OCT2 is a next generation OCT module for the SPECTRALIS platform, offering enhanced image quality and the faster scan speed needed for advanced imaging technologies such as OCT angiography*.

Imaging methods, such as fundus

auto-fluorescence (FAF) and optical coherence tomography (OCT), represent pivotal milestones in the diagnosis and monitoring of retinal diseases, allowing objective and quantitative assessment of structural eye damage. The development of OCT technology has undergone major advancements in recent years, from time-domain OCT (TD-OCT) to spectraldomain OCT (SD-OCT), as well as the recent introduction of OCT angiography (OCT-A) and other modifications in OCT technology.1 Comprehensive diagnostic made easier OCT is a multimodality imaging technology that involves the utilization of more than one wavelength of light in the simultaneous imaging of the eye. Using this technique, a comprehensive diagnostic picture is created as each image offers unique data, facilitating disease diagnosis and monitoring.2,3 The SPECTRALIS platform (Heidelberg Engineering, Heidelberg, Germany) incorporates several imaging modalities, such as the SD-OCT, the anterior segment module, infrared reflectance, BluePeak autofluorescence, MultiColor fundus imaging, fluorescein and ICG angiography and widefield and ultra-widefield imaging, making a variety of options needed to optimize diagnosis available to clinicians.4 SPECTRALIS provides cross-sectional imaging of eye tissue morphology in situ and in real time. Multimodal imaging allows for infrared retinal imaging, cross sections and auto-fluorescence, which is especially useful in examining layers of the eye such as the photoreceptors and retinal

* OCT Angiography is under development and not for sale yet.

SPECIAL REPORT on Multimodal Imaging

pigment epithelium which are strongly associated with visual function. OCT imaging is useful in the clinical diagnosis of commonly encountered eye conditions like glaucoma, diabetic macular edema, geographic atrophy, age-related macular degeneration and rare conditions.5 OCT2: next generation OCT OCT2 is a next generation OCT module specially developed for the SPECTRALIS platform, offering enhanced image quality and faster scan speeds of up to 85,000 Hz.6 A high scanning speed of this nature is important for advanced imaging technologies like the OCT angiography* and high-resolution imaging sequences in glaucoma. SPECTRALIS has optimized the functions of spectral domain OCT by incorporating confocal scanning laser ophthalmoscopy, with a specially developed, high speed TruTrack active eye tracking technology, to avoid motion-related artefacts. The AutoRescan feature places follow-up scans at the precise location for

the initial scan, thereby facilitating accurate comparison between visits, and to detect changes as small as 1 micron.

Cost effective, upgradeable platform approach A variety of options are available on the SPECTRALIS. It allows clinicians to make accurate diagnoses at the earliest time. It features a cost-effective modular design to meet the specific needs of every practice, while allowing for future inclusion of new modules and hence new clinical applications and technologies when needed.

Enhanced diagnostic accuracy of glaucoma The glaucoma module on the SPECTRALIS includes a proprietary system known as the anatomic positioning system (APS). The system utilizes unique scans of the optic nerve head, retinal nerve fiber and ganglion cell layer, and compares the patient’s eye data with that of a reference database, and then flags even the smallest deviations of the eye structures. The proven 1-micron precision of the auto rescan function allows clinicians to accurately identify and monitor structural changes from visit to visit. This is immensely important in the establishment of individualized treatments for patients.7

References: 1. Fang PP, Harmening WM, Müller PL, et al. Technical principles of OCT angiography. Ophthalmologe.

2016;113(1):6-13. [Article in German] 2. Rebolleda G, Diez-Alvarez L, Casado A, et al. OCT: New perspectives in neuro-ophthalmology. Saudi J Ophthalmol. 2015;29(1):9-25.

3. Charbel Issa P, Finger RP, Holz FG, et al. Multimodal imaging including spectral domain OCT and confocal near infrared reflectance for characterization of outer retinal pathology in pseudoxanthoma elasticum.

Invest Ophthalmol Vis Sci. 2009;50(12):5913-5918.

4. Fung TH, Yusuf IH, Xue K, et al. Heidelberg Spectralis ultra-widefield fundus fluorescein angiography in infants. Am J Ophthalmol. 2015;159(1):78-84.e1-2.

5. Huang D, Swanson EA, Lin CP, et al. Optical Coherence Tomography. Science. 1991; 254(5035): 1178-1181.

6. Witmer MT, Parlitsis G, Patel S, et al. Comparison of ultra-widefield fluorescein angiography with the Heidelberg Spectralis® noncontact ultra-widefield module versus the Optos® Optomap®. Clin Ophthalmol.

2013;7:389-394.

7. Wojtkowski M, Srinivasan V, Fujimoto JG, et al. Three-dimensional retinal imaging with high-speed ultrahigh-resolution optical coherence tomography. Ophthalmology. 2005;112(10):1734-1746. * Under development, not for sale yet.

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Retinal and choroidal vascular

involvement is a feature of many posterior segment ocular diseases, with characteristic pathologies such as geographic atrophy, neovascular age-related macular degeneration and diabetic macular edema.

These pathological changes in the retinal vasculature are temporally related and vital to optimal monitoring of disease progression.1 Current methods of diagnosis and assessment, such as fluorescein (FA) or indocyanine green (ICG) fluorescence angiography, are fraught with inherent challenges.2 For example, systemic intravenous administration of fluorescein or ICG can lead to systemic adverse events such as nausea and anaphylactic reactions, which may be potentially life threatening. Furthermore, this method is cumbersome and time-consuming for both patient and clinician.3 In this context, recent research and development efforts aimed at producing an innovative, non-invasive method to examine the eye’s vasculature have been a great source of excitement.

How OCT-A works Optical coherence tomography angiography (OCT-A) is expanding the frontiers of retinal and choroidal vascular imaging.

OCT-A is an application of optical coherence tomography (OCT) that captures minute differences in optical reflectivity within tissues such as the retina. OCT-A works by analyzing both the intensity of the reflected signal and the temporal changes in the reflection caused by particles in motion, such as intravascular erythrocytes. The OCT signal flux, measured by repeatedly recording OCT images (B-scans) at each point on the retina, creates an image contrast between the perfused vessels and the surrounding tissues.4 OCT-A offers some advantages over conventional fluorescence angiography.

Notably, OCT-A does not require the use of a contrast agent, so the associated risks of dye injection are eliminated.

Therefore, repeated imaging using OCT-A can be performed non-invasively.

Furthermore, with OCT-A, it is possible to visualize distinct vascular networks, allowing clinicians to move through the vascular networks of the retina layer by layer, at a resolution which is impossible to achieve by conventional angiographic methods.2 OCT-A is poised to augment,

OCT Angiography Module

and in many cases, replace traditional methods of examining the retinal and choroidal vasculature.

At Heidelberg Engineering, OCT-A* is based on the established SPECTRALIS imaging platform. To achieve the scanning speed needed for OCT-A, a new OCT module called OCT2 has been introduced.

OCT2 is capable of delivering an improved image quality across the whole depth of field at a considerably higher capture speed of 85,000 Hz. Thus, OCT2 is well suited for advanced applications such as OCT-A. The SPECTRALIS OCT Angiography Module* produces detailed threedimensional images of the retinal and choroidal microvasculature in a noninvasive manner.

Non-invasive vascular imaging The OCT Angiography Module* non-invasively produces detailed three dimensional illustrations of the retinal and choroidal microvasculature.

*OCT Angiography is under development and not for sale yet.

SPECIAL REPORT on OCT Angiography

use of multimodal imaging enables a more targeted approach needed for individualized treatment.

Despite the enthusiasm, it is important to recognize that the technology does have some limitations. Static or very slow flow phenomena such as capillary leakage and polyps are not well visualized on OCT-A. In such cases, it is not possible to generate sufficient motion contrast.

With OCT-A, it is also not possible to differentiate between arteries and veins in the same way as with the inflow of dye in fluorescence angiography. In addition, interpreting the 3D images may pose a challenge as this is still a relatively new technique.

Diagnostic potential and current limitations OCT-A is poised to help improve diagnosis and monitoring of eye diseases, specifically in identifying and classifying degenerative changes in the perfusion behavior of the retinal vasculature and monitoring these changes over time.4 It offers new, treatment-relevant information in a wide range of applications. The

References: 1. Zhang Q, Lee CS, Chao J, et al. Wide-field optical coherence tomography based microangiography for retinal imaging. Sci Rep. 2016;6:22017.

2. Puliafito CA. OCT angiography: the next era of OCT technology emerges. Ophthalmic Surg Lasers Imaging Retina. 2014;45(5):360.

3. Fang PP, Lindner M, Steinberg JS, et al. Clinical applications of OCT angiography. Ophthalmologe.

2016;113(1):14-22. [Article in German] 4. Fang PP, Harmening WM, Müller PL, et al. Technical principles of OCT angiography. Ophthalmologe.

2016;113(1):6-13. [Article in German] * Under development, not for sale yet.

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SPECIAL REPORT on Widefield Imaging Conventional methods of screening and assessment of peripheral retinal diseases, such as diabetic retinopathy, retinal vein occlusions, choroidal masses and vasculitis, have relied upon the use of images obtained from normal angle fundus cameras.1 However, with recent methods incorporating widefield and ultra-widefield (UWF) fundus and OCT imaging, a wider area of the retina can be imaged with fewer images, and with less dependence on a photographer’s experience and skills.

Widefield images can detect peripheral pathology not typically seen in standard photographs, which could certainly broaden our understanding of disease severity and guide new indications for treatment.

The epidemiology of diabetes mellitus is rapidly changing, and consequent upon the increasing prevalence of diabetes mellitus, the demand for diabetic retinopathy (DR) screening platforms has risen sharply in recent years. Early detection and treatment of DR are key public health interventions that have the potential to greatly reduce the likelihood of preventable loss of vision.

How SPECTRALIS OCT fits in the retinal imaging picture Currently, hospital based DR screening programs typically employ retinal fundus photography, which relies on skilled and experienced readers for manual DR screening. However, this is labor-intensive and suffers from inconsistency across sites. Hence, there has been a recent proliferation of retinal image analysis platforms, such as the SPECTRALIS (Heidelberg Engineering, Heidelberg, Germany), that may potentially alleviate this burden in a cost-effective manner.

Furthermore, conventional screening programs that rely on 2-dimensional fundus photography do not effectively screen for diabetic macular edema (DME).

Optical coherence tomography (OCT) is becoming increasingly recognized as the reference standard for DME assessment and can potentially provide a costeffective solution for improving DME detection in large-scale DR screening programs. Current screening techniques also are unable to image the peripheral retina, and require pharmacological pupil dilation; ultra-widefield imaging and

Widefield Imaging Module Widefield fundus and OCT The Widefield Imaging Module provides the standard field of view of a mydriatic fundus camera for all SPECTRALIS fundus and OCT imaging modalities, simplifying diagnostic protocols and facilitating detection of peripheral pathology.

MultiColor

confocal scanning laser ophthalmoscopy, which address these important drawbacks, are urgently needed as effective screening and diagnostic tools.

The Widefield Imaging Module available on the SPECTRALIS multimodal platform provides the standard field of view of a mydriatic fundus camera for all SPECTRALIS fundus and OCT imaging modalities, thereby simplifying diagnostic protocols and facilitating detection of peripheral pathology.

The SPECTRALIS Ultra-Widefield Angiography Module captures an extremely wide field-of-view in one shot. It delivers evenly illuminated, undistorted, high-contrast images even in the periphery. The Module is compatible with SPECTRALIS® highspeed video angiography, ultra-widefield fluorescein and ICG angiography and can

Infrared

be performed as single procedures or simultaneously. The non-contact design makes peripheral imaging with the UltraWidefield Angiography Module convenient for both patient and operator. This easy-to-use module further extends the broad range of the SPECTRALIS imaging platform.

References: 1. Saine PJ. Focusing The Fundus Camera: A Clinical Approach. J Ophthalmic Photogr. 1992;14(1): 7-24.

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SPECIAL REPORT on OCT

SPECTRALIS MultiColor Scanning Laser Imaging:

A New Level of Diagnostic Power Multi-modality MultiColor Imaging

Multiple small to mid-size drusen appear well delineated in the MultiColor image. The simultaneous SD-OCT image confirms the confluent drusen pattern.

The key features and advantages of MultiColor imaging: • Identification of fine anatomic details is made possible by the high contrast and quality of the MultiColor image.

• The presence and extent of multiple reticular drusen is readily visible.

• The full extent of subretinal and RPE alterations is revealed.

Fundus Camera

MultiColor

SD-OCT

Traditional diagnostic imaging

tools such as the color fundus camera may not be sufficient anymore in determining retinal diseases.

In screening for diabetic retinopathy and diabetic macular edema, for example, detection of early features is critical to ensure timely intervention. The shortcomings of traditional fundus photography are being addressed with the utilization of newer technologies such as scanning laser fundus imaging, optical coherence tomography (OCT) and widefield imaging.1 Compared to its predecessors, spectral domain OCT (SD-OCT) is known for a much faster acquisition time and in delivering a largely increased amount of data that can be obtained during a given scan duration.2 SD-OCT acquires all information in a single axial scan through the tissue simultaneously through evaluation of the frequency spectrum of the interference between the reflected light and a stationary reference mirror.

The SPECTRALIS MultiColor Scanning Laser Imaging (Heidelberg Engineering, Heidelberg, Germany) combines simultaneous and selective color fundus imaging and gives detail and contrast that can better help clinicians in identifying pathologies that are unclear or difficult to see in the corresponding fundus image.

Providing a new dimension in multi-modality fundus imaging with the SPECTRALIS platform, MultiColor Scanning Laser Imaging uses multiple laser colors simultaneously to selectively capture and display images of different retinal structures in one examination.

The resulting diagnostic information can then be extracted out of high contrast, detailed fundus images even in cases of difficult patients (i.e. those with cataracts, nystagmus, etc.). Simultaneous imaging using multiple laser colors provides diagnostic information that originates from various structures at different depths within the retina.

References: 1. Tan CS, Chew MC, Lim LW, et al. Advances in retinal imaging for diabetic retinopathy and diabetic macular edema. Indian J Ophthalmol. 2016;64(1):76-83.

2. Drexler W. Ultrahigh-resolution optical coherence tomography. J Biomed Opt. 2004;9(1):47-74.

• Since the MultiColor image is composed of three simultaneously acquired selective color laser images, users have the option to view both the MultiColor image and the individual color images. This versatile feature provides additional diagnostic power by highlighting structural detail from different depths within the retina.

In diagnostic imaging of DR and DME, the fundus camera and MultiColor image reveal multiple areas of fibrotic tissue due to laser photocoagulation. Areas of abnormal structure in the macula, which may be difficult to identify from the fundus camera image, are clearly visible in the MultiColor image. Furthermore, the corresponding OCT image shows diffusive thickening of the retina and cystoid macular edema.

Out of Heidelberg Engineering’s core strengths including the confocal scanning laser, active live eye tracking and noise reduction technology, the new MultiColor imaging modality of the SPECTRALIS platform was born. Experts agree that the combination of MultiColor fundus imaging and OCT in a single device puts the SPECTRALIS multi-modality platform on a whole new level of diagnostic power.