Hi tavak,
These are just the visible or permanent impressions and if this was the only issue then it probably wouldn’t be affecting you but polyfoam will also soften and have either “temporary” or “virtual” impressions that would be noticeable when you sleep on the mattress but wouldn’t be visible once you have been off the mattress for a while (see post #174 here and post #2 here).
Other than some temporary or partial effect … a topper will only help if your mattress doesn’t have any soft spots or sagging (virtual or visible) because it will “follow the sags” in your mattress. In these cases the suggestions in the post I linked earlier (post #4 here) would be the most effective options outside of removing and replacing the foam in your comfort layers or replacing the mattress.
Phoenix