>>3015288
a) An appropriate additive sphere. You'll need one that's brighter on the edges and darker toward the center, but it should be pretty bright overall, directly proportional to the transparency of the lens texture.
b) AutoLuminous can give you a glare, depending on the above material properties, but it will apply to everything, so you'll need an instance with reduced strength, where the lens is not an AL_object in AL_EmitterRT or has been made to shine (null specular values, reflectivity over 105).
c) A PBR system with high material reflectivity (ClearCoat/Metallic) and texture opacity, preferably still using sphere maps (for Ray-MMD, main_ex_with_sphmap.fx), but it will reflect your skybox, which may not be desirable.
>>3015283
Another reason to start using MikuMikuMoving with its motion layers.