The active ingredient in Can-C is N-acetylcysteine (NAC).
I tried Can-C in 2014, but I gave up after 1 month because it made my yellow cataracts more yellow. I also tried Brite-Eyes III, but it didn't work either and the same thing happened. I wondered why these products made them more yellow/brown. I read somewhere on the Net that it's because NAC goes down the same metabolic pathway as the lens proteins, so you end up with the same colored end-products. Still, some researchers say that if the cataracts are in the very early stage, then the ingredient in Can-C and Brite-Eyes (NAC) can reverse them. In fact there are lots of testimonials on the Web from people who said it worked for them, although I have read a few which said it didn't work, probably because the cataract was too far advanced.

It didn't work for me, but there are so many testimonials from people who say it did work for them that it would be difficult to call it a fake. I remember one optometrist who had tested Can-C on his cataract patients a few years back. He found that it did reverse cortical cataracts (on the edge of the lens), but that it had absolutely no effect on nuclear cataracts (in the center of the lens) or posterior subcapsular cataracts, or PSC (at the back of the lens). Although the makers of Can-C claim it does improve not only cortical, but nuclear and PSC cataracts too.