I deal with lights and IES files on a daily basis. My work method is to go from Revit to 3ds max for rendering with iray.

I've noticed a few potential issues going from MR to iray.

My strategy in MR for realistic lights that glow is as follows:
Place IES file in (lighting) fixture
Set fixture to not cast shadows
Add a self illumination to fixture material and make sure it does not actually emit light

This makes fora good rendering since the glowing fixture throws accurate light. Normally you do not want the IES file to send any light that would touch the fixture itself since IES files are calculated as the result of the fixture output including the body, reflectors, collimators, etc.

Now with iray, I can't seem to make the IES file not be interrupted by the fixture geometry. As well, any self illuminating surface actually emits light.

The purpose of iray is to create a fully photorealistic rendering solution. However, right now, it is preventing me from achieving this realistic effect.

Does anyone have any tips on creating accurate light fixtures that:
Accurately emits IES file light without the light touching the geometry
Has a glowing aperture without the glowing surface casting light

I do come from Revit rather than from 3ds, so some 3ds technicalities and subtleties are likely to have been ignored. Thanks.