In the UK, club breeders are looking to breed as close to the National Hamster Council’s exhibition standards as possible and these cover things like colour, type (shape), fur quality, size and the size and shape of the eyes and ears. Many of these standards have been set with health in mind as a poorly shaped head for example, can cause things like bulging eyes.
The standards for Syrians can be found:
https://hamsters-uk.org/joomla30/ind...tion-standards