What is the role of optical coherence tomography (OCT) in the workup of optic neuritis in multiple sclerosis (MS)?

Updated: Feb 21, 2019
  • Author: Fiona Costello, MD, FRCP; Chief Editor: Hampton Roy, Sr, MD  more...
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Optical coherence tomography (OCT) is a noninvasive ocular imaging technique that provides high-resolution images of retinal architecture in vivo.

Changes in peripapillary retinal nerve fiber layer (RNFL) thickness represent axonal damage, whereas loss of macular volume and ganglion layer thickness provide indirect measures of neuronal injury in the afferent visual pathway. [24] In the context of acute optic neuritis, OCT-measured peripapillary RNFL thickness tends to be elevated in the optic neuritis eye initially presumably owing to axoplasmic flow stasis. [24] In contrast, macular volume and ganglion layer measures, as determined with OCT, are comparable between affected and unaffected eyes of patients at symptom onset but later decline for up to 12 months. [24]

Postacute visual outcomes including high- and low-contrast letter acuity, color vision, and visual field sensitivity correlate with the amount of OCT-measured RNFL, ganglion layer, and macular volume loss detected 6-12 months after optic neuritis. [24]

Recurrent optic neuritis has been associated with worse OCT measures. In a study of pediatric patients with CNS demyelinating syndromes, there was a 9-μm (9%) decrement in RNFL thickness for each additional optic neuritis episode. [25]

One disadvantage of OCT is that a so-called floor effect can complicate detection of new changes in RNFL thickness in the setting of pre-existing optic atrophy, since mean RNFL values do not decrease below a measure of approximately 30 μm, regardless of the extent of optic nerve injury. [24]

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