Railway Group D posts are classified under a medical fitness category in the notification — most Group D posts need the A-2 or B-1 standard. The medical test checks vision (with and without glasses), hearing, blood pressure and general physical fitness. Colour vision requirements are strict for posts involving signals and tracks. If you fail the medical for your allotted post, you may be considered for a lower medical category post. Wear your prescribed glasses to the medical exam and carry your medical records.