When i look closely i see the reflection appears to be drawn on the eyes themselves. If that is so, in a cave the eyes would still show that line of trees, which would not actually be there. Using the env_map spherical you can achieve something similar to reflection so if you had a picture of an environment that would fit most situation then yes, you can.
Just in case people reading this want to try it
{
receive_shadows off
technique
{
pass
{
lighting on
scene_blend alpha_blend
specular 0.5 0.5 0.5 1 128
cull_hardware none
cull_software none
texture_unit
{
texture Eyetextureofyourchoice.png
}
}
pass
{
lighting on
scene_blend alpha_blend
texture_unit
{
env_map spherical
texture semi-transparentReflection.png
}
}
}
That's what i'd use anyway. Yours may differ.
Edit, made the mistake of using specular on my eyes once. When the eyes were closed the eyelids were shiny.