Evaluation of retinal nerve fibre layer thickness and visual evoked potentials in optic neuritis associated with multiple sclerosis

Background: The aim was to compare the retinal nerve fibre layer (RNFL) thickness and visual evoked potentials (VEP) among eyes with multiple sclerosis (MS)-associated optic neuritis, unaffected eyes of the same patients and eyes of disease-free controls. Changes in RNFL thickness, visual acuity (VA) and VEP over time are evaluated in MS-associated optic neuritis. Methods: Forty-six eyes of 23 patients (six male and 17 female), who suffer from MS and were diagnosed with unilateral or bilateral optic neuritis, participated in the study. Forty eyes of 20 age-and gender-matched controls were tested. VA measurement, optical coherence tomography and VEP were performed in all patients at presentation and at one, three and six months thereafter. Results: There was a statistically significant difference in VA between MS eyes with optic neuritis and controls (p < 0.0001), as well as between MS eyes with and without optic neuritis (p < 0.005). VA improved over time. Average RNFL thickness was reduced in MS eyes with or without optic neuritis in comparison to control eyes. This reduction in RNFL thickness was more marked over time. The amplitude of P-100 was significantly decreased in MS eyes with optic neuritis in comparison to controls (p < 0.0001) and there was a statistically significant delay in peak time of P-100 in MS eyes with optic neuritis versus the eyes of normal subjects (p < 0.0001), which improved over time. Conclusion: The present study suggests that there is a progressive decrease in RNFL over time in eyes with optic neuritis associated with MS. The amplitude and latency of P-100 in VEP examination returned to normal ranges over time.