Because patients with visual field (VF) defects under binocular vision are more prone to car accidents, researchers in Japan have created a new self-check tool to help them recognize the problem and adjust accordingly. The clock chart binocular edition (CCBE) uses four targets displayed at 10°, 15°, 20° and 25° eccentricities. The patient rotates the chart 360° clockwise and, at every 30°, confirms the fixation and indicates if they can see all four targets.

The researchers enrolled 44 patients (88 eyes) with glaucoma and 32 visually normal individuals (64 eyes) to test the new tool. In addition to the CCBE test, they also captured static 30-2 VF testing using the Humphrey field analyzer (HFA) and binocular Esterman programs.

They found the CCBE had sensitivities of 85% and 82% with respect to the HFA and Esterman results, respectively. When using British VF standards for the glaucoma group (car/motorcycle) drivers, and a sensitivity of 88% was obtained for the CCBE.

The CCBE test had sensitivities of 85% and 82% with respect to the HFA and Esterman results, respectively. They also used the British VF standards for car and motorcycle drivers, and found the chart had a sensitivity of 88%. It had a specificity of 100% for the visually normal subjects.

“The CCBE test enables drivers with glaucoma to notice their VF abnormalities under binocular condition,” the researchers conclude. “The application of this simple self-check method appears promising for occasions such as driver licensing.”