I had cataract operations on both eyes and the UK CAA requirement was that I was grounded from the day of the first operation until six weeks after the second operation, which in my case meant a total of eight weeks. The requirement to have my medical reinstated was simply that I underwent a Comprehensive Eye Examination at my local optician and submitted the results to the CAA.
Once this had been done it took the CAA less than 48 hours to contact me and wish me happy flying.