A functional scoring method for the field of binocular single vision.

The authors present a new method for plotting and quantitating the field of binocular single vision (BSV). They modified a Goldmann perimeter to project a fusion target in the form of a cross (+). Unlike previous methods that used a spot, which is a poor fusion target that cannot detect cyclotorsion, the authors' method permits a single tester to plot BSV fields in patients who have any combination of horizontal, vertical, and cyclotorsional diplopia. The BSV fields were plotted in 23 patients with acquired diplopia using both the fusion target and the spot. Scoring was performed using a new scoring template weighted to the functionally important areas around primary and reading positions. Nine patients (39%) had scores for the two targets that differed by more than 10%. The authors' method yields BSV scores that are reproducible and easy to perform and that can be used for preoperative and postoperative assessments, serial monitoring of changes over time, and disability evaluations.