A visura is simply a land search. Its what you get on paper at the land registry office, though the visura itself may be misleading.
If you need to do a land search go through a specialist. Usually notaries have their own specialists. If in doubt ask a notary or his secretary, he'll usually be able to come up with someone competent.
If you contact a geometra he'll probably say that he is capable. This is often true, but if the property is very old the land registry may not be up to date, therefore ask an expert to search.