Routine eye exams and eyeglasses are generally not a covered item under Medicare. If you have had cataract surgery, speciall corrective lenses are usually a covered medical expense with your Medicare plan.
If you contact an approved Medicare supplier, they can tell you how much Medicare will pay towards the cost of eyewear. Go to Medicare.gov and search for "Supplier Directory"
Unfortunately, Medicare does not pay for eyeglasses. The only situation in which eyeglasses are covered by Medicare is when cataract surgery is done. Then it will pay for one standard pair of glasses following surgery. To find out what amount is allowed for that expenditure you can ask your Medicare provided or call 1-800-MEDICARE.
If you contact an approved Medicare supplier, they can tell you how much Medicare will pay towards the cost of eyewear. Go to Medicare.gov and search for "Supplier Directory"