Intraoperative Monitoring of the Integrity of the Anterior Visual Pathways: A Methodologic Review and Meta-Analysis

Diverse methods have been developed for intraoperative monitoring of the integrity of the visual pathways. We performed a review of the literature to determine the methodology of each technique as well as their recent development. The predictive power of each eligible technique was determined based on a meta-analysis. A literature review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Techniques adopted for intraoperative monitoring of the integrity of the visual pathways were extracted and described. The power of each eligible technique to predict the visual outcome was tested. Visual evoked potentials showed marked methodologic improvement in recent studies. Predictive power for visual deterioration after surgery was approximately 60% and reached 100% when coupled with simultaneous monitoring of electroretinography. The sensitivity of visual evoked potentials for detection of deterioration was 47.2%. The decrease of fractional anisotropy of the optic chiasma showed significant correlation with improvement of vision after chiasma compression and showed 100% predictive power for improvement. Each technique had limitations. Visual evoked potentials had a high predictive power for detection of deterioration but with low sensitivity. Fractional anisotropy of the optic chiasma had high predictive power for improvement of vision with low predictive power for deterioration.