I humbly suggest getting those after market pull-down shades. I got them for my city. advantages are 1. you don't get the defogger lines busted 2. you can remove them when u want and simply put it back on for the freaks with HIDs trying to blind you. 3. uncompromised vision at nigh time.
Otherwise, if you have a run-of-the-mill car like a khyber cultus etc, you can get yourself one of those black blinds with metallic boundaries that you fix on the side windows. they have them for the rear window now too. Saves the hastle of a permanent change to your rear screen and is cost effective.
Just my two cents worth. Hope it helped. My civic vti defogger got busted after the previous owner got it tinted. i hated him for doing that to an otherwise wonderful car.