Utility of CLOCK CHART binocular edition for self-checking the binocular visual field in patients with glaucoma.

Background/aims: Car accidents caused by drivers unaware of their visual field (VF) defects under binocular vision have become an issue. We developed a simple self-check chart (CLOCK CHART binocular edition (CCBE)) to help patients with glaucoma recognise their abnormalities in the binocular VF and evaluated its usefulness.

Methods: The chart has four targets displayed at 10°, 15°, 20° and 25° eccentricities. The examinee gradually rotates the chart 360° clockwise. At every 30°, the examinee confirms the fixation and indicates if all four targets can be seen. This study enrolled 88 eyes of 44 patients with glaucoma (mean age, 64.4±13.1 years) and 64 eyes of 32 visually normal individuals (mean age, 32.0±8.4 years). Except the CCBE test, static VF testing using the Humphrey field analyser (HFA) Swedish Interactive Threshold Algorithm-Standard 30-2 and binocular Esterman programmes was also performed for the subjects with glaucoma.

Results: VF abnormality was defined as two or more contiguous points with a sensitivity of <10 dB within the central 30°. The CCBE test had sensitivities of 85% and 82% with respect to the HFA and Esterman results, respectively. We also used the British VF standards for Group 1 (car/motorcycle) drivers, and a sensitivity of 88% was obtained for the CCBE. The chart had a specificity of 100% for the visually normal subjects.

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