You didn’t. If you get a retinal tear and then don’t get treatment you’ll end up with permanent vision loss. It’s a major medical emergency. If all you had was a flash and nothing else, it wasn’t a retinal tear.

Your doctors might be concerned about retinal detachment which can be just as serious though. If they think you’re a high risk for it it’s worth getting anything abnormal checked out.

There are many causes, so possibly nothing you’d even be aware of.