Readers' Forum

Electronic Disinfection - A Possible Remedy for Red Eye

readers' forum

Electronic Disinfection ­ A Possible Remedy for Red Eye

March 2001

Contact lens-associated red eye has been more prevalent since the introduction of chemical disinfection. When soft contact lenses first hit the ophthalmic market, there was only one method of disinfection ­ heat. It was very effective as long as the unit was reliable. Solution allergies were unheard of, and finding the right solution was not a big problem.

Solution Overload

Today is a different ballgame. Most grocery stores, pharmacies and "marts" devote an entire aisle to solutions. Many patients switch from one solution to another, trying to find one that will not cause some symptom that makes contact lens wear less tolerable.

Patients come in complaining of decreased lens tolerance, variable foreign body sensation, sensitivity to lights and decreased wearing time. Slit lamp examination invariably shows a chemical keratitis where a multi-purpose or some other chemical solution has leached out during lens wear and over time caused a toxic reaction that can take weeks to resolve.

Granted, some patients do just fine with a chemical regimen. However, for those who have allergies or chemical keratitis, or who want a fast, convenient, inexpensive and safe way to disinfect their contact lenses, we feel this new computer chip-controlled EarthEyes Electronic Disinfecting Unit ( is a viable option.

Low Water-Content Lenses Work Best

Several years of research have resulted in this cost-effective heat disinfecting unit driven by a computer chip. The chip turns the unit on and off. A complete cycle lasts for one hour. Plugging in the unit activates the chip. After 30 minutes at 160 degrees F, the chip turns the unit off. The cool-down cycle lasts 30 minutes. The cycle will not start again until the unit is unplugged and plugged in again, unlike heat units from the past whose on-off cycle was actually an unpredictable electrical "shorting out" process.

Patients selected to use the units varied. Some suffered from solution allergies and solution intolerance, some were noncompliant with their present disinfecting regime and some simply asked if heat units were still available. Most were already wearing a lens compatible with the heat unit. Low-water content lenses are typically the most compatible for heat disinfection, particularly polymacon and tetrafilcon. Lenses used in our study included Bausch & Lomb Optima 38 series, Soflens series U3-U4 and O3-O4 (polymacon) and Gold Medalist Toric and Optima Toric (helficon); CIBA Vision Cibasoft Softcolors and STD (tefilcon); CooperVision CooperClear, Vantage, Preference PR and Preference Toric (tetrafilcon); Ocular Sciences Edge III and Hydron Biomedics 38 (polymacon); Wesley Jessen Aquaflex (tetrafilcon), CSI and CSI Toric (crofilcon), DuraSoft 2 D2T3 and D2T4 (phenfilicon) and Softmate B (bufilcon); and Biocompatibles Proclear (omafilcon). There are many other lenses with compatible material. Our study patients used nonpreserved saline (Unisol or Lens Plus) and Pliagel or Miraflow cleaning solutions.


Vistakon Acuvue, although not a recommended material to be heated, does nicely through four heat cycles, after which it starts to discolor. This prevents patients from trying to extend the life of these lenses, encouraging more frequent replacement.

Our success rate for eliminating solution allergies and intolerance is 100 percent. The Earth Eyes Electronic Disinfecting Unit is not the next wave. But it is dependable, inexpensive and an effective addition to our contact lens disinfection arsenal.

Dr. MacDonald, is in private practice in Wilmington, OH. Dr. Martin is in private practice in Dayton, OH.