I finally got to speak with the researcher who found the cause of senile cataract back in 1996 (see link in previous post). She told me that the only way to get rid of the damaged lens proteins in cataract, is for the immune system to recognize them and destroy them. In a normal lens, there are two enzymes that "mark" damaged proteins for deletion: Ubc4, and Ubc5. They form part of what is known as the "ubiquitin-proteasome system".  

https://www.researchgate.net/publication/10803755_Lens_fibers_have_a_fully_functional_ubiquitin-proteasome_pathway

 Quote: The finding that supplementation of Ubc4 or Ubc5 partially restored the ubiquitin conjugation activity and presumably ubiquitin-dependent degradation capability prompts us to speculate that targeted expression of Ubc4 or Ubc5 may enhance the degradation of abnormal proteins in lens fibers and prolong the transparence of the lens .(2003)

In addition to these, there is one protein, thioredoxin (TRx), its reducing enzyme, TRx reductase, and yet another enzyme, thioltransferase (TTase), which together repair the damaged lens and maintain lens clarity.

http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0420.2007.01063_3156.x/full

Quote: Conclusions: TTase (thioltransferase) and TRx (thioredoxin) systems can repair oxidation damage and restore protein/enzyme functions in the lens. TTase is essential to lens clarity. ​(2007)

Thus, all these factors: Ubc4, Ubc5, TRx and TTase, are found in a normal lens, but their levels decline with age.  This explains why humans get senile cataracts, because the damaged proteins simply can no longer be removed, therefore they accumulate unchecked. Amazingly, the same four anticataract factors: Ubc4, Ubc5, TRx and TTase, are all present in live yeast cultures.

https://www.ncbi.nlm.nih.gov/pubmed/2154373

Quote: We have cloned the genes for two novel ubiquitin-conjugating enzymes, UBC4 and UBC5, from the yeast Saccharomyces cerevisiae. These enzymes mediate selective degradation of short-lived and abnormal proteins. (1990)

http://aem.asm.org/content/73/5/1672.long,

Quote: We demonstrated in this study that thioredoxin can be extracted from yeast cells with 20% ethanol.(2007)

But, it is not possible to safely consume live yeast. Now brewer's yeast tablets were sometimes used in Europe to treat cataracts, but yeast contains significant amounts of tyramine, which if consumed together with monoamine oxidase (MAO) inhibitor drugs or some common foods with similar activity, can cause dangerously high blood pressure, and contains purines which can raise uric acid levels. I also don't think dry yeast tablets contain enough of these enzymes. It is interesting though that around the year 2000, it was found that beer drinkers had 50% less cataracts, and in 2005, red wine drinkers also had 50% less. However, this benefit was seen only in those who consumed 1 glass/day, and no more.