Night myopia is often difficult to assess in routine refraction. The myopic shift under scotopic conditions is often bothersome to many of our patients. Since the extent of the shift is variable from one person to another we have put together flippers to establish an overcorrection for each individual.
You can loan your patients a set of flippers to determine if more minus is needed while driving or star gazing before making a second pair of glasses for use at night. University Lowbrow Astronomers Naked Eye Observer’s Guide