I had never noticed the fogging of my headlights until I had my car parked next to a friend's '85, and what a difference! With much help from the Search function here, I found the advice (from John Walker as I remember, among others) to remove the assembly and clean the inside using Isopropyl alcohol (91%) and some dry rice to shake around inside, to do the scrubbing. It worked like a charm!
Be sure to remove the dessiccant pack that attached to the bottom of each lamp assembly first, once you have the lights out of the car. I then used my thumb to plug up that hole, filled the reflector / lens assembly with about 1/3 cup of the alcohol and probably 1 Tablespoon of dried rice (long grain brown rice, actually!). Shake it around for a while, then quickly pour out the fluid to get as much rice out as possible. I then rinsed the assembly out with clean cold water until all the rice was out, shook out as much water as possible, and finished with another 1/3 cup of rubbing alcohol, shaken around vigorously. I let them air dry overnight, and what a difference! See the photo below of my before and after.
Hope that this helps someone else.
