Myths and Realities about Spectral-Domain and Swept-Source OCT

The commercial introduction of swept-source optical coherence tomography (SS-OCT) technology with long wavelength lasers has triggered extensive investigation to assess the clinical diagnostic benefits that the technology’s fast acquisition speed, minimal signal roll-off, and long depth penetration may offer. Does SS-OCT technology offer diagnostically relevant advantages relative to spectral-domain OCT (SD-OCT) technology?

Current commercially available SD-OCT and SS-OCT devices use lasers of different wavelengths to acquire OCT images in the same way. The difference between these two technologies could be likened to the difference between a diesel and a gasoline engine. Both engine types are quite similar, each having distinct advantages and disadvantages, but they alone do not determine the performance of the vehicle. The same holds true for SD and SS technologies: Both can perform at varying wavelengths, speeds and powers. Each offers unique benefits, but there are trade-offs to consider.

Learn how Heidelberg Engineering has optimized these two technologies and paired them with the optimal laser wavelengths to expand its multimodal imaging platforms. This detailed whitepaper, backed by the latest scientific evidence, explains how Heidelberg Engineering combines its core technologies to deliver images that empower clinicians.

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Speed trade-offSpeed trade-off

While SS-OCT technology offers the potential advantage of fast OCT acquisition speeds, the fastest commercially available OCT device is an SD-OCT device. Acquisition speed has its advantages, but it is important to remember that there is a trade-off between sensitivity and speed.

Penetration trade-off

The sensitivity of OCT devices largely depends on laser power. A long wavelength SS-OCT laser allows for the use of more laser power, at the cost of signal attenuation due to water in the vitreous. Deeper penetration into the choroid with a longer wavelength comes at the cost of reduced contrast of retinal layers.

Optimizing technologies

SPECTRALIS® SD-OCT combines dual-beam active eye tracking technology with fast scanning speeds and a short wavelength laser to deliver high-contrast and high-resolution images of the retina. Contrast and resolution are vital for reliable segmentation of all retinal layers and resulting analytics. At the same time, SPECTRALIS choroid images are comparable to SS-OCT in visualization of clinically relevant content.

Capitalizing on the depth penetration and signal roll-off capabilities of long wavelength SS-OCT technology, ANTERION® combines eye tracking and optimized electronics technology to capture high-contrast and high-resolution images from the anterior surface of the cornea to the posterior surface of the lens, providing the most important anterior segment examinations and measurements in one modular, upgradeable platform.

Optimizing technologies
Left image acquired with SPECTRALIS OCT2 Module – With a fast scanning speed of 85 kHz for enhanced image quality from vitreous to choroid. (Image by Matteo Cereda, Milan, Italy)
Right image acquired with ANTERION – High-resolution SS-OCT image of the entire anterior segment.

Get in touch with your Heidelberg Engineering contact person to discuss how both SD-OCT and SS-OCT images can empower you to continue making confident diagnostic decisions that benefit your patients.