It is your choice whether to have cataract surgery, however, for the majority of people it is the only treatment for the condition. For those with complex cataracts, there may be a risk if they are not treated, your team will be able to advise if this is the case.
During surgery, the cloudy lens is removed and replaced with a clear artificial lens.
For most people, once treated, vision is restored to how it was before the cataract developed and it is rare that there isn't a noticeable improvement. If your vision is more complicated, however, perhaps due to another eye condition, your consultant will be able to explain to you the level of improvement to expect.
Once treated, your vision can return to how it was before the cataract started developing (as long as no other eye conditions are affecting sight).