OCT can be used to determine axonal damage and optic nerve atrophy by measuring retinal nerve fiber layer (RNFL) thickness and macular volume (MV) in patients with MS.¹  RNFL thinning may be predictive of future axonal damage, and decrease in MV has been associated with optic neuritis (ON).¹  The thinning of RNFL and decrease in MV are more marked in progressive forms of MS compared with relapsing types.

In ON and MS, axonal loss is an early pathologic feature, regardless of clinical recovery and lack of clinical symptoms. Axonal degeneration in the RNFL of patients with MS observed by OCT can be detected in some patients before any visual signs or symptoms of ON appear. Therefore, by detecting axonal loss and ON, OCT may help to identify patients who have early-stage MS.²

A recent study³ found that, even in the absence of ON, progressive RNFL thinning occurs as a function of time in some patients with MS and is associated with clinically significant visual loss. These findings are consistent with subclinical axonal loss in the anterior visual pathway, and support the use of OCT as a method of measuring the efficacy of potential neuroprotective agents. OCT technology may provide a promising biomarker in future trials that measure neuroprotection in MS.

1. Trip SA, Schlottmann PG, Jones SJ, et al. Optic nerve atrophy and retinal nerve fibre layer

thinning following optic neuritis: evidence that axonal loss is a substrate of MRI-detected

atrophy. Neuroimage. 2006;31:286-293.

2. Pulicken M, Gordon-Lipkin E, Balcer LJ, Frohman E, Cutter G, Calabresi PA. Optical

coherence tomography and disease subtype in multiple sclerosis. Neurology. 2007;69;2085-2092.

3. Talman LS , Bisker ER, Sackel DJ, Long DA Jr, et al. Longitudinal study of vision and retinal nerve fiber layer thickness in multiple sclerosis. Ann Neurol. 2010;67:749-60.