Which is the best filter to remove poisson noise?

I have the image attached and I should remove noise/noises. Observing image histogram (attached) I supposed that it is affected by poisson noise. I used wiener filter to remove noise, but in my opinion it isn't the best solution. Can you suggest me a better filtering method to improve the image visualization?

[Silvia Caruso]

This is the result of the wiener2 filtering.