Purpose: Optic neuritis (ON) observed during neuromyelitis optica (NMO) is in most cases very severe and with poor prognosis. This study's objective was to analyze visual field (VF) abnormalities observed in the absence of ON and post-ON episode.
Methods: Twenty-seven cases of both NMO and multiple sclerosis (MS) were selected. Thorough ophthalmologic exam was performed at least 6 months post-ON attack. The VF was collected using the Humphrey 750 perimeter. We used the central threshold tests 24-2 with FASTPAC strategy. The abnormalities were categorized based on the Optic Neuritis Treatment Trial classification.
Results: After one ON, 40% of the NMO group's eyes showed total VF loss (P = 0.01), 21% showed abnormalities of neurologic aspect, and 27% showed fascicular abnormalities of which 12% were altitudinal. Given the total VF loss, the positive predictive value in favor of an NMO was 92.8% and the negative predictive value was 47.3%.
Conclusion: Alterations of the VF during the NMO differ from those observed in the course of the MS. One ON, blinding from the first attack, must call to mind an NMO. The altitudinal deficits point to a vascular mechanism.
Keywords: multiple sclerosis; neuromyelitis optica; optic neuritis; visual field.