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The eye is a window to the brain; but who’s looking?

As an extension of the central nervous system, the eye offers a window to the brain. Since the advent of optical coherence tomography (OCT) imaging, in vivo cross-sectional imaging of the human retina has become commonplace, facilitating quantitative measurements of neuronal layer thicknesses at the micron scale.

Pioneering work by the group led by Professor Calabresi at the Johns Hopkins University School of Medicine has shown that intra-cranial volumes are associated with OCT-derived parameters in Multiple Sclerosis (MS) patients and healthy controls[1]. In particular:

  • Retinal nerve fiber layer (RNFL) and ganglion cell complex (GC-IPL) thicknesses correlate with whole-brain volume.
  • Inner nuclear layer (INL) thickness correlates with T2 lesion volume.
  • Outer nuclear layer (ONL) thickness “may reflect the global nature of neurodegeneration in MS”.
  • These findings create direct associations between brain and retinal structures that may be used clinically.

But what of other neurodegenerative diseases as seen using retinal OCT imaging? The associations there are more than compelling:

  • In Alzheimer’s disease, the correlates are measures of the RNFL, GC-IPL and INL [2,3].
  • In Parkinson’s, its the GC-IPL, ONL and OPL [4,5].
  • In amyotrophic lateral sclerosis (ALS), the RNFL and the INL are used [6].

And this is likely just the tip of the iceberg because the issue here is that, although the eye may indeed be a window into the brain, who exactly is looking? A brief survey of OCT instrumentation available in the US reveals the following dearth of analytical functionality:

Available Oct Analysis Software
Comparison of layer segmentation functionality offered in the U.S.

Of course, we’ve added our own software, Orion™, to the list as we do offer such functionality.  At Voxeleron we are committed to addressing these technology gaps to help advance the capabilities of OCT analysis software, with the goal of accelerating the pace of discovery in this critical area of medicine.

[1] Saidha S, Sotirchos ES, Oh J et al. JAMA Neurol. 2013 Jan;70(1):34-43.
[2] Marziani et al., IOVS September 2013 54:5953-5958.
[3] Chang et al., Program No. 710.13, Society for Neuroscience, San Diego, 2013.
[4] Bayhan et al., Current Eye Research, 2014.
[5] Schneider et al., Journal of Neural Transmission, January 2014, Volume 121, Issue 1, pp 41-47.
[6] Ringelstein et al., Annals of Clinical and Translational Neurology, Volume 1, Issue 4, pp 290-7, April 2014.