What's Inside: Bausch and Lomb ReNu
Contact lens solution has to strike a balance between killing germs and not burning your eyes when you pop the lenses in. Dymed (polyaminopropyl biguanide) is an antimicrobial agent that attaches to bad little bugs and rips open their cell membranes, letting their guts spill out. Fortunately for your eyeballs, it only works on single-celled organisms.
Known by chemists as hydroxyalkylphosphonate, it removes protein deposits, eliminating the hassle of a separate enzyme treatment. The eye's lubricating fluid contains mucus protein, which over time can build up and cloud your vision like a snot cataract. Hydranate is a compound that traps the mucus molecules and lifts them off the surface of the lens.
It's a fire retardant, a nuclear-reaction controller, and the stuff that turns silicone oil into Silly Putty. Grandma knew it as an antiseptic eyewash; here it's also a pH buffer. But boric acid has been tagged by the feds as an infant-killing poison. There's only a dash in ReNu, so don't worry—unless you experience one of the more memorable symptoms of boric acid toxicity: blue-green vomit.
This commonly used compound sequesters metallic ions (calcium from tears or possibly particles from air pollution) that might otherwise react with the lens.
Made of multiple oxyethylene and oxypropylene segments, poloxamine is used in gene therapy as an alternative to artificial viruses for carrying DNA into cells. In this solution, it's just a surfactant that ensnares lipids so they can be washed away.
More widely recognized under the alias Borax, it's the same crystalline alkali dust found in Death Valley. It's added to ReNu as a buffering agent, keeping the solution at a comfy pH of 6.5 to 7.8, so you never have to utter the words "Ahhh, my eyes!"
Since soft lenses are liquid permeable, you want to make sure that your cleaning fluids are as osmotically close to tears as possible. That calls for a pinch of salt—otherwise, the lenses would dry out. Add too much, of course, and your lenses will suck all the moisture out of your eyes, get oversaturated, and start to weep. Creepy.