Table 1 Comparing methods and percentage of patients with isolated optic neuritis with baseline abnormalities on magnetic resonance imaging (MRI) and nearest regional prevalence estimate of multiple sclerosis.
| Years of recruitment | MRI slice thickness (mm) | Age range (years) | Maximum time from symptom onset to MRI | Percentage with abnormal MRI | Multiple sclerosis prevalence (per 100 000)7 | |
|---|---|---|---|---|---|---|
| London, England, n = 135 | 1995–2004 | 3 | 16–49 | 3 months | 77 | 104 |
| Stockholm, Sweden, n = 1163 | 1990–1995 | 5 | 12–57 | 24 weeks | 65 | 96 |
| Copenhagen, Denmark, n = 1204 | 1987–1993 | 4 | 12–59 | 4 weeks | 53* | 112 |
| North America, n = 3892 | 1988–1991 | 5 | 18–46 | 8 days | 54† | 858 |
| Barcelona, Spain, n = 1235 | 1995–2001 | 5 | 14–50 | 3 months | 51 | 57 |
| Japan, n = 706 | 1991–1996 | Not specified | 15–55 | 14 days | 14 | 1–4 |
*In the Danish study, abnormal MRI was defined as the presence of at least two lesions, and data for one or more lesions were not given; therefore, these data were not included in fig 1. †Data represent the 90% Optic Neuritis Treatment Trial cohort in whom MRI findings are reported.