I had cataract surgery 2years ago. but now at night the headlights from other cars have halos around yhem. what is happening?

Haloes: If the haloes are new, then i would see an eye doctor to determine the cause. I would be suspicious of a secondary cataract or posterior capsular opacification. If this is the cause, it can be removed with a laser in clinic. Other issues can also cause this problem so be sure to get this evaluated.

Capsule clouded: One of the most common causes of blurred vision and halos after cataract surgery is clouding, or opacification of the capsule behind the new lens. If this is the case the fix is an easy, in office laser procedure. See your ophthalmologist to determine the cause of your symptoms.

Could be scar tissue: After cataract surgery, sometimes scar tissue can grow behind the lens implant and cause symptoms similar to the original cataract. Its very common. A yag laser can be used to polish the lens by blasting the scar tissue.