Abstract
Abstract: :
Purpose:to investigate whether the multifocal visual evoked potential (mfVEP) can reliably differentiate among normals, optic neuritis (ON) patients and anterior ischemic optic neuropathy (AION) patients. Methods:We tested 45 healthy volunteers, 22 patients with ON and six with AION using conventional automated perimetry (CAP) with the Humphrey SITA Standard 24–2 and mfVEP (ObjectiVision Accumap). Statistical comparisons examining latency and Accumap Severity Index (ASI) were performed. The empiric probability plots for amplitude deviation (maximal peak–to–trough), amplitudes less than 90nV, and intereye asymmetry were also analyzed. Results: Using ANOVA on ASI values of the affected, unaffected and normal eyes in the three groups, statistically significant differences (P < 0.001) were manifested for the following comparisons: AION affected and normal; ON affected and normal; AION affected and AION unaffected; and ON affected and ON unaffected. The sensitivity of mfVEP using the 90nV measure in all patients was found to be 75%, for maximal peak–to–trough 79%, and for intereye 82%. The specificities were 96%, 100%, and 87% respectively. The sensitivity for CAP was 82% with a specificity of 98%. All AION patients showed concurrent defects in CAP, 90nV, maximal peak–to–trough, and intereye asymmetry evaluations. Only 50% of ON patients showed defects with both mfVEP measures. Furthermore in the ON patients, the sensitivities were CAP: 77%, 90nV: 68%, maximal peak–to–trough: 73%, and intereye: 77%. Latency analysis of the major peak revealed a statistical difference (P < 0.001) using ANOVA on ranks between the ON and normal groups; there was no significant difference between the normal and AION groups. Conclusions: The mfVEP is useful for detecting ON and AION and latency differences may be useful in distinguishing ON from AION.
Keywords: visual fields • visual impairment: neuro–ophthalmological disease • electrophysiology: clinical