Can backpacks cause spider veins?

I am 18, and I recently noticed that I have spider veins on my shoulders. I thought maybe it was from sleeping on my side all the time, but then I realized that I carry a backpack all the time. I don't do purses, so I carry a little backpack every day even when I'm not carrying my school backpack. Can backpacks cause spider veins? Should I stop carrying a backpack?