DY, contact lenses do not absorb large amounts of water. Put a contact lens in tap water and the water content will not change. The water in contact lenses is added in the manufacturing process and varies from about 24% to about 70%. (if it matters here, and it probably doesn’t, the addition of methacrylic acid will allow for huge amounts of water to be absorbed) Different lenses can have different water contents and still have the same “softness”. Natural evaporation will dehydrate a lens exposed to air, and therefore the lens must be in a water environment at all times. If constant slight water absorption to counter slight constant evaporation is a halachic problem, then we have a serious one. The lens in vivo retains its original water content by taking water from the tears, and so, putting the lens on an eye causes this process to occur and wearing lenses on shabbos would then be assur. Second, putting the lens in any solution, even saline or noncleaning solution would be assur. But all this is irrelevant.
Water is a very small molecule and will pass through the hydrogel lens. As the water passes through, it does not clean the lens, wash the lens, or remove dirt from the lens, it just keeps it at its original water content.
The halachic issue here is kibus, laundering. What needs to be removed from the lens are particles that adhere to the lens on its outer surface and not inside the matrix of the lens. There is nothing to remove from inside the lens, as protein and lipid and anything else excepting water and some ions are too large to enter the matrix of the lens.90% of these particles are removed by manual rubbing, just like rubbing dishes with water or with your fingers. The rest is removed by a cleaning agent, but again, only from the outside. This is exactly what dishwashing liquid does to a dirty dish, whether the dish is hard or soft (rubbery).
If the issur we are discussing is not kibus, then most likely “soft” contact lenses would be forbidden to wear on shabbos. I have not heard a posek say this, but if one did, I can justify the issur. Tikun kli comes to mind, but I’ll leave that alone.
Nishtdayngesheft, you have shown that you cannot contribute to this discussion on any level, halachic or scientific. Please take your Mr. Potato Head and play nicely in the corner until the adults have finished.