Convergence insufficiency after prk?

Latent muscle proble: This sounds like something present but hidden prior to the surgery. I have never heard of refractory surgeries causing muscle imbalances.

Not caused by it: Prk does not cause convergence insufficiency. It was probably there before, and just showed up after surgery.

Unlikely: Convergence insufficiency is not usually associated with prk although it is possible with corrected hyperopia since accommodation is stimulated less once hyperopia is corrected. If the hyperopia was previously corrected with glasses or contact lenses it should not worsen with prk.