The medical standards for Group 2 licence entitlement (LGV/PCV) are higher than Group 1 (Car). As a result of this, the DVLA requires a medical report form ‘D4’ form to be completed by a registered medical practitioner as part of the application process. This link explains how the DVLA set the medical standards for a variety of driving licences:
The following are required at the examination:
The D4 form will be completed after the medical examination ready to return to the DVLA. The individual will be told if there have been any abnormal findings that might affect the issue or renewal of the license.