Do lazy eyes as a child usually lead to bad vision as an adolescent?

Sometimes. It also depends on what you mean by lazy eyes. It can mean amblyopia to some people, which means poor vision, but it can also mean eyes that are not straight. I'll assume you mean the latter. Some children alternate seeing with each eye, so they develop both eyes. Some children ignore one eye, and the brain that connects to that eye never develop, causing amblyopia..