I went to my optometrist years ago and decided to be honest. I told him I was only using saline because of the cost.
He picked up a bottle of the solution I should have been using and walked me over to the Hydrogen Peroxide. (Yes the brown bottles for 50 cents!) They have the same ingredients! The only difference is the label, check it out.
This system works well with the Aosept cups that have the hole in the top. It is very important to let the air out overnight. You will see and here the bubbles. The air will convert the Peroxide (H2O2) into water (H2O)
Remember to rinse with saline. This was just before the multi-purpose solutions came out so it was always two steps.
I used this for many years with no ill effects before I went back to glasses.