Well, I'm one of the people who believe that the supplements work as I've had good experiences myself. I've got the beginnings of cataracts and was suffering with glare problems in bright sunlight. The summers of 2014 and 2015 I really struggled. However, I put myself on Visual Eyes which contain Lutein and Zeaxanthin, and this summer I have had almost no problem with glare ... and in fact because my eyes seemed as normal as they used to be, I had forgotten my previous problems, and suddenly realised I no longer had to squint in bright sunlight.
MargaretX Pharmaceutical companies can't patent these supplements, hence they will not market them as they couldn't earn money from them.
I collapsed with M.E. 26 years ago, and was bedridden for 2 years with no cure via conventional medicine. Fortunately I was brought up to be open-minded and tried various alternative therapies, hand-in-hand with nutrition and supplements. One has to be discerning, of course, and I am no fool, but some of these things do indeed work, and the key (especially now we have the Net, whereas 26 years ago I only had the library!) is to do your research.