PROGNOSTIC VALUE OF MAGNETIC-RESONANCE-IMAGING IN MONOSYMPTOMATIC OPTIC NEURITIS

Purpose: Magnetic resonance imaging is able to depict lesions in the o ptic nerve in the acute stage of monosymptomatic optic neuritis. Most patients have lesions located intraorbitally, intracanalicularly, and/ or intracranially. The goal of this study is to determine whether thes e lesions resolve after visual recovery, change in length or localizat ion, or could be correlated to the visual function. Methods: Between 1 987 and 1992, the authors examined 22 patients with acute optic neurit is using magnetic resonance imaging short-time inversion recovery sequ ences. Additionally, the authors determined visual acuity, visual fiel d, color vision, contrast sensitivity, and visual-evoked responses. Al l patients were re-examined between 1993 and 1994 in the same manner. Visual recovery in the re-examination was divided into three groups: g roup 1 with complete visual recovery (visual acuity better than 20/25) ; group 2 with incomplete recovery (visual acuity better than 20/25 bu t defect in at least one of the other tests: visual field, color visio n, and contrast sensitivity); and group 3 with partial recovery (visua l acuity remained less than 20/25, defect in all the other tests). Res ults: All group 1 patients initially had lesions less than 17.5 mm, gr oup 2 patients had lesions greater than 17.5 mm (44%) and/or lesions l ocated intracanalicularly (66%), and most of group 3 patients initiall y had lesions greater than 17.5 mm (79%). Conclusion: Eyes with lesion s less than 17.5 mm in the optic nerve in acute optic neuritis have a good prognosis for visual recovery. Lesions greater than 17.5 mm or le sions involving the intracanalicular portion of the optic nerve lead t o incomplete or partial visual recovery.