Although zwitterionic material "SIB" is ionic and has high water content, it has the advantage of keeping away the proteins, which cause deposits.
CONVENTIONAL IONIC LENS
The negative ions in the material strongly repel each other, hence making the lens surface negatively charged. Therefore, it attracts the positively charged deposits, e.g. proteins.
ZWITTERIONIC MATERIAL “SIB”
There are equimolar amounts of positive and negative ions in the material. Thus, there is no deviation of charge on the lens surface. Therefore, it doesn’t attract positively charged deposits e.g. proteins.