You have to differentiate between red eye and enlarged blood vessels.Healthy people can have white eye but with enlarged blood vessels. There are no eye drops that can be used in these healthy eyes to shrink these blood vessels permanently.
Red eye with enlarged blood vessels is another issue and you should find the cause of it. There are many causes of it such as viral, bacterial, allergic or autoimmune conjunctivitis. Each cause has its own eye drops and treatments.