Neither retinal nor brain atrophy can be shown in patients with isolated unilateral optic neuritis at the time of presentation.

BACKGROUND: Acute monosymptomatic optic neuritis (ON) may be the earliest manifestation of multiple sclerosis (MS). Atrophy has been shown to be a prominent feature of MS with great impact on disability.

OBJECTIVES: The objectives of this study were to evaluate retinal and brain atrophy and possible associations at the earliest possible stages of MS.

METHODS: In a prospective observational cohort study we included 60 untreated patients with monosymptomatic ON and 19 healthy volunteers. Unaffected fellow eyes were examined with optical coherence tomography (OCT) and normalized brain volumes were calculated based on MRI. Additionally, visual evoked potentials (VEPs) were recorded.

RESULTS: Neither OCT measurements nor brain volume measures revealed signs of localized or generalized atrophy in patients compared with healthy volunteers. Stratification of patients into high risk based on the presence of white matter lesions did not reveal differences. The association between OCT measures and brain volumes previously found could not be confirmed at the time of the first clinical event. VEP latency was significantly prolonged in patients with white matter lesions compared to those without lesions. A trend towards a relationship between VEP amplitude of fellow eyes and brain volumes was noted.

CONCLUSIONS: In this cohort we were not able to show atrophic features in the retina or the brain, and the association between structural measures of the retina and the brain as indicated in the later stages of MS could not be reproduced. These findings suggest that atrophy does require time to evolve and indicate the complexity of the relationship between local and general structural measures.