• CSLO
  • What information
    does CSLO provide?
• SLP
  • What information
    does SLP provide?
• OCT
  • What Information
    does OCT provide?
    • Limitations
    • Imaging Artifact

OCT

OCT is a non-invasive technology that provides high-resolution images (10–17 microns) of retinal structures (peripapillary NFL and ONH). OCT analyzes the interference pattern created when light reflected back from the retina is combined with light reflected from a reference mirror. The back-scattered light from the retina is affected by the depth of retinal structures. This means that the interference pattern can be used to assess structural features of the ONH/RNFL.

The application of optical coherence tomography (OCT) in imaging the eye was first described in 1991. The first generation commercial device was released by Humphrey Instruments (now Carl Zeiss Meditec, Inc.) in the mid 1990s. Upgrades (models 2000 and 3000 [OCT3]), giving faster scanning and greater sampling in depth, followed. The current version (OCT3 or Stratus OCT) gained FDA approval in January 2002.

OCT technology is rapidly progressing. The Stratus OCT is an example of “time domain” OCT. Newer instruments are “frequency (or spectral) domain” and permit more rapid data acquisition and generate 3-dimensional image blocks, compared with the 2-dimensional line scans of the Stratus OCT. Several manufacturers produce frequency domain OCT devices, and these will become widely available.

Figure: Stratus OCT (Carl Zeiss Meditec, Inc.)