Eye problems with PPMS

My husband went to the optician’s today and they think he may have double vision, she wants to see him next week again to test further, she thought it may be double vision, even though my hubby says he’s not seeing double. He does tend to close one eye a lot of the time. Anyone else had this and what treatment is there for it? He has PPMS, diagnosed 4 years ago, but never had any issues with his eyes , as I was led to believe this was one of the first signs of MS. Anybody else had the same?