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Federica Ristoldo, Yuyi You, Alessandro Invernizzi, Alexander Klistorner, Clare Fraser; Relationship between Uhthoff Phenomenon and demyelination in the visual pathways in multiple sclerosis. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2283.
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© ARVO (1962-2015); The Authors (2016-present)
Patients with multiple sclerosis (MS) can experience Uhthoff Phenomenon (UP). The aim of this study was to investigate the possible correlations between the presence of UP and microstructural/functional alterations in the visual pathway of patients diagnosed with MS.
Consecutive MS patients with and without history of optic neuritis (ON) were enrolled. According to their answers to a questionnaire patients were classified as UP-positive or UP-negative. A group of age- and sex- matched healthy controls was also enrolled. All subjects underwent best correct visual acuity (BCVA) assessment, optical coherence tomography (OCT) scans, and multifocal visual evoked potential (mf-VEP) recordings. Correlations between the presence of UP and structural and functional changes in the visual pathways were investigated.
Ninety-six subjects (72 females/24 males) with MS were included.Forty-four patients had unilateral ON, among whom 47.7% were UP-positive. Eyes with ON in UP-positive subjects had significantly higher mfVEP amplitude than those in UP-negative subjects (141.5±48.5mv vs 111±41.7 mv, p<0.03). These eyes also had significantly shorter mfVEP latency (163.8±14ms vs 173±16.5ms, p<0.05) and better BCVA (0.08±0.21 vs -0.05±0.21 LogMAR, p<0.03). Retinal nerve fibre layer (RNFL) and Ganglion cell inner plexiform layer (GCIPL) thicknesses in ON eyes were not different between the two groups.UP was present in 59.6% of the subjects without ON (non-visional symptoms). Eyes without ON had significantly delayed mfVEP latency in UP-positive compared to UP-negative patients (153.6±11.6ms vs 148±6.7ms, p<0.02). No other differences were found between these two groups. Both UP-positive and UP-negative patients without ON had significantly thinner RNFL compared to controls (both p<0.05). UP-positive patients also had thinner GCIPL than controls (p=0.001).
In ON eyes, patients experiencing UP had better visual outcomes and less myelin loss in the optic nerve than UP-negative subjects. Conversely, in non ON eyes, UP suggests more severe demyelination in the entire visual pathway. Therefore, UP could represent a sign of different patterns of damage in the visual system in MS.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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