3.1. Calculation of Visual Disability Percentage

To calculate the residual visual coefficient (RVC), the binocular VA value expressed in hundredths is multiplied by the residual binocular VF percentage using the following formula: VA × VF%/100. For example, a subject with a binocular VA of 2/10 (=20/100) and a binocular VF score of 88 (88/504 × 100 = 17.46%) will have a CVR of 20 × 17.46/100 = 3.5%

The visual disability coefficient (VDC) is then calculated using the following formula: 100 − RVC (considering the percentage of a perfectly normal subject as 100). Therefore, the subject in the preceding example would have a VDC of 100 − 3.5 = 96.5%.

Thanks to the algorithm incorporated into its software, the digital visor automatically calculates and displays on its screen the numerical value defining the disability percentage of the subject under examination.