What is the Difference Between OCT Spectral and Time Domain?

Optical Coherence Tomography (OCT) is a diagnostic imaging technique used to obtain detailed, cross-sectional images of biological tissues, such as the retina. There are two main types of OCT: Time Domain (TD-OCT) and Spectral Domain (SD-OCT). The key differences between these two methods are:

1. Technology: TD-OCT uses interferometry-based technology to generate images with an axial resolution of 10 μm. In contrast, SD-OCT uses a spectrophotometer and Fourier transformation to generate images with a higher resolution, ranging from 1 to 6 μm.
2. Acquisition Time: SD-OCT has a much shorter acquisition time compared to TD-OCT, allowing for an increased retinal area to be imaged per session.
3. Measurement Repeatability: SD-OCT has better measurement repeatability compared to TD-OCT.
4. Retinal Thickness Measurements: The algorithms used by SD-OCT differ from those of TD-OCT, and the retinal thickness measurements are not directly comparable between the two methods.
5. Clinical Impact: While SD-OCT does not change the ultimate treatment decision, it increases the certainty of retina specialists in their treatment decisions.

In summary, SD-OCT offers higher resolution, faster acquisition times, and better measurement repeatability compared to TD-OCT. However, the two methods are not interchangeable, and their clinical applications may differ slightly.

Comparative Table: OCT Spectral vs Time Domain

Time Domain (TD) OCT and Spectral Domain (SD) OCT are two types of optical coherence tomography used in ophthalmic imaging. Here is a table highlighting the differences between them:

TD OCT uses interferometry-based technology to generate images with an axial resolution of 10 µm. On the other hand, SD OCT uses a spectrophotometer and Fourier transformation to generate images with a higher axial resolution than TD OCT. SD OCT also allows for faster acquisition speeds of A-scans, enabling denser sampling of the area of interest in seconds. Both TD and SD OCT are reliable for macular thickness measurements, but SD OCT has better measurement repeatability compared to TD OCT.