My father has cataract in both eyes. However, he refuses to get it operated. He uses some eye drops every day and says that he finds these drops really useful and there isn't a need for operation. Is it true that some eye drops can actually cure cataract? Is getting an operation done really important?

No, the drops will slow (sometimes) them from getting worst, but not stop it, only his doctor can give you his exact issues, so why not go to doctor with him, most likely at some point he will lose most of his sight without surgery

Surgery is so easy and painless. They do one eye at a time a few days apart. I'm 66 and everyone I know (practically) is getting it done, so I guess I'm next in a few years. Find family and friends his age who have had it done and get them to encourage him.