During my last flare of severe dry eye, my ophthalmologist recommended that I only use the Systane preservative free individual applicators. You twist off the top and use it once, then discard. There’s about 30 in a box. I normally prop it up and use throughout the day. It’s still pricey. And, night time ointment. Also, preservative free, but in a tube. Very expensive as well, imo. And, not covered by insurance. At least with my diabetic costs, I get credit for it.