Sensitive Assessment of Acute Optic Neuritis by a New, Digital Flicker Test.

Background: The Aulhorn flicker test (AFT) previously showed promise in diagnosing acute optic neuritis (ON) albeit with suboptimal sensitivity. A new, digitalized version of the AFT (the DFT) has not previously been examined in acute ON. Objectives: To examine the sensitivity, specificity and reproducibility of the DFT in acute ON. Method: The DFT assesses the subjective brightness of a flickering field (1–60 Hz). In normal subjects, brightness enhancement occurs at intermediate frequencies, whereas in acute ON darkness enhancement (DE) is hypothesized. AFT and DFT measurements were obtained in acute ON patients (≤31 days from first symptom) with DE as a quantitative covariate. Reproducibility of the DFT end point was assessed in the form of an intraclass correlation. Results: 30 untreated first-time acute ON patients and 55 healthy controls were examined. AFT and DFT were performed 12.7 days (range: 4–30) following ON onset. The DFT showed a sensitivity of 0.93 (95% CI = 0.78–0.99) to a specificity of 0.96 (95% CI = 0.87–1.00). The AFT showed a sensitivity of 0.76 (95% CI = 0.56–0.90) to a specificity of 1.00 (95% CI = 0.93–1.00). No significant correlation was shown between DFT and visual acuity. The intraclass correlation of the DFT end point in healthy subjects was 0.84. Conclusions: We present a new DFT in acute ON displaying a high specificity of 0.96 and a sensitivity of 0.93. Our study indicates the DFT to be an accurate and easy-to-use tool in diagnosing acute ON, which may be especially helpful in atypical cases. [ABSTRACT FROM AUTHOR]