Tap Water Effectively Rinses RGPs, But Presents Ocular Surface Disease Risks

Tap water demonstrates superiority to contact lens rinsing saline solutions for removing cleaning debris from rigid gas permeable (RGP) lenses, according to a study published in Eye & Contact Lens. However, it presents an increased risk for ocular surface disease and inflammation and should not be used in contact lens care, the report asserts. 

Researchers used 1 of 2 commercially-available contact lens cleaners to clean a corneal (Plano sphere; base curve [BC], 8.0 mm; diameter, 9.6 mm) and scleral RGP (Plano sphere; BC, 7.85 mm; diameter, 15.88 mm) and rinsed the anterior and posterior surfaces for 30 seconds each with 1 of 5 saline solutions or tap water. After air drying the lenses for 15 seconds, the team used high resolution imaging to capture the solution film forming on the RGP surface and determine light transmission. The team used a venous pressure transducer system to measure the exiting fluid pressure of each solution, and tested each product until obtaining a minimum of 10 separate pressure measurements. 

The investigators noted variations in lens surface opacity following rinsing with the different saline solutions. Tap water, which had the highest exiting fluid pressure, demonstrated the best ability to remove RGP cleaners from the lens surfaces. There was no significant difference between cleaner brands across rinsing methods with the corneal or scleral lenses (P =.06), according to the report.  

While tap water most effectively removed debris from the RGP surfaces, the researchers do not suggest using it in the rinsing process. 

“Although tap water was the most effective lens rinsing option tested, tap water is not sterile, and relying on its use during cleaning and disinfection of contact lenses can be problematic and is unequivocally not recommended,” the study authors caution. “These results demonstrate the importance of developing alternative products, methods, or tools to effectively remove abrasive cleaners from the surface of [gas permeable] contact lenses.”

Study limitations include an inability to measure fluid pressure of the faucet tap and an inability to determine whether tap water tap pH affects its ability to remove lens surface cleaner.