Is there a way to have a light only specular? i.e. as in Poser, to get a light that has no diffuse, no shadow, only specularity to emphasis the eyes reflects for example.

.... not in Esprit, sorry! You need the LightTune module.

So how could i do to obtain realistic eyes? I mean reflection maps not work in all case. So is there another trick to increase reality in eyes?

Maybe you could use a black & white image as a variablereflections  fonction, try any interior photo with a strong light coming from a window, the window would ideally be in the center of the photo,  turn it b&w with a very strong contrast and use it as a variable reflections function. Or paint a b&w image yourself. Then use an hdr file for lighting your scene, the hdr will reflect in the eyes according to the image you loaded as a variable reflections function.

You can maybe use the chrome studio HDR in Vue,it makes kewl reflex(;

Erm, I use VUE 6 Infinite and use this effect all the time. If you click the light settings icon on your light, and influence, you can choose specular, diffuse, or both.

Not in Esprit, Warangel.