For something similar but diferent: I actually remember a kid who needed to wear an eyepatch because said eye had far better sight to the other, to the point that it caused him headaches. The idea behind the treatment was that by only using his worse eye, it would eventually "catch up" to the other.Which was what I was arguing in the first place: it's a made-up disease (or a fictional variant of an existing one) that's specifically tailored for Nova so she can have some sort of limiter to an advantage that would absolutely be OP if it didn't come with said limiter.
Thinking about it, wouldn't it be hilarious if eventually, we discover that nova's condition is actually some kind of superpower she has yet to master ? Wouldn't be too far-fetched given the supernatural element present in their world.