Tracking changes over time in retinal nerve fiber layer and ganglion cell-inner plexiform layer thickness in MS
Diagnosis, monitoring and biomarkers:
Eyes of people with MS provide a unique opportunity to study axonal degeneration. The retinal ganglion cells and their naturally unmyelinated axons in the eye can be evaluated in vivo using spectral domain optical coherence tomography (OCT).
This study investigated if there was progressive neurodegeneration in MS eyes without clinically evident inflammation in patients with RRMS (eyes without a history of optic neuritis (ON), and eyes with a previous history of ON but where the inflammatory event was at least six months prior to the onset of this study). OCT was used to measure retinal nerve fibre layer thickness (RNFLT) and ganglion cell-inner plexiform layer thickness (GCIPT). 93 patients were scanned at two visits. From this data, the change in RNFLT and GCIPT over time was analysed cross-sectionally and longitudinally. Relations between RNFLT/GCIPT and MS duration were assessed.
The results clearly showed that progressive loss of RNFLT and GCIPT occurs in the absence of clinically evident inflammation in RRMS eyes. There were significantly more abnormal eyes in the GCIPT measurements than in the RNFLT measurements both for non-ON eyes and ON eyes.
The progressive neuronal loss, in the absence of clinically evident inflammation, suggests a significant role for neurodegeneration in RRMS. This highlights the need for new therapies to focus on remyelination and neuroprotection in addition to reducing inflammation and relapses.
: Narayanan D, Cheng H
Mult Scler. 2014 Mar 17. [Epub ahead of print]