My cataracts are yellow nuclear cataracts. I excerpted the following from an article which appeared in 2011:
"The ageing lens and cataract: A model of normal and pathological ageing"
"(b) Nuclear cataract
Strictly defined, a nuclear cataract is a lens opacity confined to the true nucleus of the lens whose shape is determined by the concentric arrangement of the fibres that compose it. Since the light-scattering properties of the lens nucleus increase progressively after the fourth decade, the point at which an increase in light-scatter may be designated a nuclear cataract becomes a matter of clinical judgement. While in some respects the molecular basis of nuclear cataract may be seen as an extension of those age-related events responsible for increased stiffness, light-scattering and coloration of the lens nucleus, it is the oxidative events discussed above, facilitated by the lack of nuclear GSH, that are the hallmark of nuclear cataract . These are responsible for the formation of mixed disulphides and PSSPs, high molecular weight aggregates and increasing protein insolubility, which lead to lens opacity and the augmented accumulation of chromophores. These changes occur within the fibres of the lens nucleus with limited structural effect, which explains the gross morphology of the cataract".
In the same article, we find:
"With increasing levels of oxidative stress, proteins become thiolated by GSSG, cysteine and to a lesser extent γ-glutamyl cysteine, to form the mixed disulphides, PSSG, PSSC and PSSγGC . These mixed disulphides may be further oxidized to form protein–protein disulphides (PSSPs), which are found increasingly in the high-molecular-weight, water-insoluble (WIS) fraction of the lens proteins, containing large, light-scattering, protein aggregates ".
First we remark that "disulfide bonds" can be broken by sulfites (the preservatives found in wine), and by a "sugar alcohol" known as "erythritol" (which is used as an artificial sweetener). There are even eye drops for dry eye which contain erythritol. Such eyedrops also contain electrolytes like potassium citrate that would interfere with the electrical attraction between proteins. It is this electrical attraction that causes the proteins to aggregate and form a cataract (so electrolytes are a very good idea), but sometimes also calcium chloride (I don't like the idea of dosing the eye with calcium salts, especially since calcium salt microspheres trigger macular degeneration). This more or less disqualifies these eye drops. But the next paragraph gets more interesting:
"Mixed disulphides and protein disulphides of this kind can be partially restored to their native state by two key redox repair systems. The GSH-dependent enzyme system, TTase, also known as glutaredoxin, exists in cytosolic and mitochondrial forms and catalyses the dethiolation of PSSG. The GSSG formed is recycled to GSH. Lens epithelial glyceraldehyde-3-phosphate dehydrogenase (G3PD) activity can be restored by TTase after H2O2 challenge, as may other SH-sensitive glycolytic enzymes such as hexokinase and pyruvate kinase .
The NAPDH-dependent enzyme TRx, present in both cytosolic and mitochondrial forms, reduces intra- and inter-molecular protein disulphides (PSSP). TRx is restored to its reduced state by TRx reductase (TR), with NADPH acting as a hydrogen donor. TRx works cooperatively with TTase to restore protein structure, conformation and function. Like TTase, TRx activity is also upregulated in response to oxidative stress. Both TTase and TRx systems can reactivate G3PD oxidized during the exposure of human epithelial cells to H2O2. Their activity, together with that of GR, falls with age ."
Therefore, apart from sulfites and erythritol, we see that the two enzymes TTase and TRx can at least "partially restore the protein disulfides to their native state". As noted in other posts, those two enzymes are found in brewer's yeast, which explains why brewer's yeast supplements are used to treat cataract.
When it boils down to it, this 40-page article is a thorough, in-depth evaluation of nearly all aspects of our problem - although the fact that cataract aggregations are largely the result of electrostatic interactions between lens proteins (Murugappan, 2010) is not mentioned. What is frustrating, as usual, is that the authors, despite having a complete understanding of cataract and the tools to reverse it at their disposal, MAKE NO ATTEMPT TO DO SO.
What is even more amazing: This article is published in the "Royal Society - Philosophical Transactions". But our lives depend on this information - there is nothing 'philosophical' about it.
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