The Radiesse filler should last up to one year or longer in an area such as the bridge of the nose, where there is no muscle movement. (However, for some Senior Citizens it may dissipate sooner)
It is hard to understand why in your case it lasted only a little over 5 months. (Unless you are a Senior Citizen)
Do you have preinjection photos? Ifd not, ask the Dr who injected the Radiesse to give you copies and to also take post injection photos and compare them to your present appearance.
Why did the Radiesse dissipate so fast?
1-Did you massage it a lot?
2- Are you wearing very heavy eyeglasses or poorly fitting eyeglasses?
It is possible that your second injection may last longer, beacuse the first Radiesse implant must have caused some extra collagen production by stretching the collagen fibers.