If you are enrolled in a Medicare Part C Medicare Advantage plan, the managed care plan itself, rather than Medicare, decides what is covered and what is not. The plan's decision about coverage must follow the terms set out in the plan's contract, a copy of which you receive when you enroll. And the coverage provided must be at least as extensive as the coverage provided by traditional Medicare Part A and Part B.
A Medicare Advantage plan must cover "medically necessary" care for cataracts, including surgery, plus glasses or contact lenses following the surgery. But it sounds like you are considering a special kind of surgery and the implanting of special intraocular lenses that would allow you not to need glasses following the surgery. It may be that the copayments for the lenses and the surgery that the Medicare Advantage plan says you'll have to pay out of pocket are due to the fact that the kind of surgery and lenses you are considering are not "medically necessary." In other words, there is a simpler surgery and less expensive intraocular lenses that could be implanted, though that would mean you'd need to wear glasses afterwards. Another way of looking at it is that if Medicare or a Medicare Advantage plan agrees that you need a car (cataract removal), it will pay for a Chevrolet (standard surgery plus glasses) but not a Cadillac (special surgery plus reSTOR lenses).
Check with your doctor and with the plan directly about the reasons why you would have to pay these amounts. If the reason is that the special lenses and surgery for them are not "medically necessary," you may want to discuss alternatives with your doctor.