how frequently does Lucentis need to be given?

Frequently!
The good news is that Lucentis works very well...and in most patients...vision can at least be stabilized...but often improved...dramatically.
The bad news...is that Lucentis eventually gets absorbed from the eye...and the effect wears off.
When the initial studies were published in 2005...showing the great success of Lucentis...patients had received MONTHLY injections for TWO YEARS
In 2009...most retinal specialists try to tailor treatment to the individual patient...and to his or her response to treatment...in most patients...significantly less than 24 injections are required in the first two years