Disc swelling and mild initial visual acuity loss predict a better short-term visual acuity outcome in bilateral acute optic neuritis.

Bilateral acute optic neuritis (AON) is rare in adults in Western countries, but is relatively common in Asian populations. We aimed to document clinical features in Chinese patients with bilateral AON, and to identify factors that are predictive of visual acuity outcome. We reviewed 41 patients (23 males, 18 females; age 18-74 years) diagnosed with bilateral AON from three centers between 2003 and 2009. Demographic and clinical data were compared to a group of patients with unilateral AON. Univariate analysis and multivariate linear regression were used to identify prognostic factors. We found that the median visual acuity (expressed as the logarithm of the minimal angle of resolution [LogMAR] scores) in our patients was 1.55 at presentation and 0.72 at discharge (p<0.001). There was a higher proportion of males (56% compared to 34%, p=0.015), a higher percentage with disc swelling (71% compared to 48%, p=0.014), and poorer visual acuity at presentation (median LogMAR scores: 1.55 compared to 1.70, p=0.001) in patients with bilateral AON than in those with unilateral AON. Both disc swelling (p=0.036) and visual acuity at presentation (p=0.023) were significantly associated with visual acuity at discharge. Our study suggests that bilateral AON has some clinical differences to unilateral AON, and that disc swelling and initial visual acuity may predict a short-term visual acuity outcome in bilateral AON.