Relationship between Optical Coherence Tomography and Electrophysiology of the Visual Pathway in Non-Optic Neuritis Eyes of Multiple Sclerosis Patients

Abstract

PurposeLoss of retinal ganglion cells in in non-optic neuritis eyes of Multiple Sclerosis patients (MS-NON) has recently been demonstrated. However, the pathological basis of this loss at present is not clear. Therefore, the aim of the current study was to investigate associations of clinical (high and low contrast visual acuity) and electrophysiological (electroretinogram and multifocal Visual Evoked Potentials) measures of the visual pathway with neuronal and axonal loss of RGC in order to better understand the nature of this loss.MethodsSixty-two patients with relapsing remitting multiple sclerosis with no previous history of optic neuritis in at least one eye were enrolled. All patients underwent a detailed ophthalmological examination in addition to low contrast visual acuity, Optical Coherence Tomography, full field electroretinogram (ERG) and multifocal visual evoked potentials (mfVEP).ResultsThere was significant reduction of ganglion cell layer thickness, and total and temporal retinal nerve fibre layer (RNFL) thickness (p<0.0001, 0.002 and 0.0002 respectively). Multifocal VEP also demonstrated significant amplitude reduction and latency delay (p<0.0001 for both). Ganglion cell layer thickness, total and temporal RNFL thickness inversely correlated with mfVEP latency (r = −0.48, p<0.0001 respectively; r = −0.53, p<0.0001 and r = −0.59, p<0.0001 respectively). Ganglion cell layer thickness, total and temporal RNFL thickness also inversely correlated with the photopic b-wave latency (r = −0.35, p = 0.01; r = −0.33, p = 0.025; r = −0.36, p = 0.008 respectively). Multivariate linear regression model demonstrated that while both factors were significantly associated with RGC axonal and neuronal loss, the estimated predictive power of the posterior visual pathway damage was considerably larger compare to retinal dysfunction.ConclusionThe results of our study demonstrated significant association of RGC axonal and neuronal loss in NON-eyes of MS patients with both retinal dysfunction and post-chiasmal damage of the visual pathway.

How strong is the relationship between glaucoma, the retinal nerve fibre layer, and neurodegenerative diseases such as Alzheimer’s disease and multiple sclerosis?

“…These findings are further supported by Sriram et al 113 who demonstrated a significant latency delay and amplitude reduction in multifocal VEPs of 62 MS patients with no previous history of ON, and an inverse correlation of GCL, total and temporal RNFL thickness with multifocal VEP latency. 115 Macular OCT segmentation shows a significant decrease in GCL thickness 113 and volume in eyes of MS patients when compared with disease-free controls. GCL and inner plexiform layer thickness measurements may predict generalised axonal damage in MS more sensitively than RNFL analysis in MS. 116 Histological studies 117 have corroborated OCT findings, identifying involvement of the inner nuclear layer, with significant atrophy noted in 40% of MS eyes, with no atrophy in control eyes.…”

Pathophysiological basis of low contrast visual acuity loss in multiple sclerosis

“…The channel with the largest amplitude (difference between min and max within the interval of 70–200 msec) was selected for each segment of the visual field. The second peak of the wave of maximum amplitude for the selected channel of each segment in the visual field was used for latency analysis of the baseline test, as previously described 31. Figure 1 demonstrates examples of mfVEP recording.…”

Optical Coherence Tomography for the Radiologist

“…Although the loss in neuronal tissue is greatest on the side with clinically symptomatic optic neuritis, MS patients without optic neuritis also have reported decreases in RNFL thickness. 40,41 This finding suggests that there are attacks of clinically silent optic neuritis or there is a progressive RFNL degeneration over time. Changes in inner retinal thickness of the macula region have also been reported in patients followed up with longitudinally, illustrating the importance of RGC analysis for progression analysis in this patient group.…”