One of the answers claim that there is no restriction for Visit Visa for a person who is 60 years or older and that the restriction is only for a Work Visa. This is incorrect unfortunately, the law does not permit Visit Visas for anyone above the age of 60, however as rightly mentioned by another user in his message, you would have to approach the Captain at the Airport Immigration and obtain his approval.

My wife's father is above 60 years of age and each time we approach the Immigration for a Visit Visa, they rejecct it and then we have to request the Captain and explain that it is only for the weekend or only a few days and that he is perfectly fine in terms of health.

There was this once when the Captain even asked us whether we are sure that the relative is physically not tired or ill. The purpose of this restriction is understandably to ensure that the residents don't bring their old relatives who are in need of medical attention to Qatar and treat them for relatively higher standard world-class medical facilities at government subsidised costs.

Hope my message has been useful to you my friend.

Cheers!