Outer Retinal Dysfunction in the Absence of Structural Abnormalities in Multiple Sclerosis

Abstract

We recorded outer retinal dysfunction without detectable abnormalities of the corresponding retinal layers in MS patients, not ascribable to retrograde degeneration following ON. The findings complement a growing body of literature reporting primary retinal abnormalities distal to the ganglion cell-inner plexiform layer complex in MS patients, with our data suggesting that this may be a more widespread phenomenon than previously thought. ERG may be of more utility in detecting retinal dysfunction in MS patients than MF-ERG. Analysis of peak times, rather than response amplitudes, is recommended.

Empirical Mode Decomposition-Based Filter Applied to Multifocal Electroretinograms in Multiple Sclerosis Diagnosis

“…Our findings show that as in previous studies [7,16], the outermost rings (R4 in our case)-as well as the nasal quadrant [18]-and therefore those close to the optic disc, show greater alteration. In the case of [18], significant affectation in mfERG amplitude and latency at the inferonasal (p = 0.045) and superonasal (p = 0.042) quadrants is reported in MS patients with and without prior ON.…”

“…Our hypothesis is that the glutamate imbalance would be transported anterogradely from the brain by the axons, reaching the optic nerve. It would be possible to detect topographical retinal dysfunction in the outer rings and the nasal quadrant in the form of an increase in mfERG amplitude in early-stage MS. With time, in later or more severe stages [7,15,[17][18][19] there would be a decline, as was detected in [17], in which 5 out of 7 patients showed decreased amplitude with predominant macular thinning when examined using optical coherence tomography.…”

“…It should likewise be noted that the studies conducted include patients with different subtypes of the disease and with or without optic neuritis (see Table 3). In MS diagnosis based on the amplitude and latency parameters of first-order kernel waves in previous studies, prolonged latency is the altered parameter found most frequently [7,15,16,18,19], and even Neroev et al [19] suggested using the latency of wave P1 in the parafovea as a marker of MS progression. The studies that detected the classical parameters with greatest alteration (lower amplitudes or higher latencies) in MS patients generally employed a 61-hexagon test [7,16,18,19].…”

“…Using electrophysiological tests, it is possible to evaluate cell function by analyzing the electrical responses that neurons generate during synaptic transmission of information. In the case of MS, this altered function can be detected and quantified by tests such as measurement of visual evoked potentials, which evaluate the integrity of the posterior visual pathway [6], or by full-field electroretinography (ffERG) [7], which evaluates total retinal response [8].…”

“…However, the few papers that have investigated the potential of mfERG analysis for diagnosing MS are based on traditional analysis of amplitudes and latencies and have produced conflicting findings [7,[15][16][17][18][19][20], perhaps because of the heterogeneity of the subjects analyzed (different types of MS and presence/absence of ON) and the use of different mfERG technologies.…”