Application Note: Optical pH measurement of contact lens solutions

Various sources estimate that more than 125 million people worldwide wear contact lenses – their popularity having grown appreciably as lenses have become safer and more effective…

To ensure contact lens safety, however, there is a caveat: to avoid eye irritation and infection, lens wearers must exercise proper care and handling of lenses and lens accessories. Yet in a 2014 study of contact lens wearers in the US, the Centers for Disease Control and Prevention reported that a remarkable 99% of lens wearers engaged in at least one hygiene-related risk behaviour,1 from sleeping overnight in their lenses to not replacing contact lens cases frequently enough.

IN THIS application note, we focus on the potentially risky practice of using contact lens solution past its expiration date, utilising optical pH measurements to demonstrate how the effectiveness of solutions changes over time and falls below healthy levels.