Peroxide neutralisation time

The peroxide neutralisation time is the period required to convert hydrogen peroxide in a lens solution into water and oxygen. Peroxide solutions are used to clean and disinfect contact lenses, but hydrogen peroxide itself is too harsh for the surface of your eye. It must therefore be neutralised before you put the lens back into your eye.

Neutralisation usually takes place via a catalyst, such as a platinum disc in the lens case or a neutralising tablet that you add. During this process, the hydrogen peroxide breaks down into harmless substances. The time this process takes varies depending on the system and is always stated in the solution’s instructions for use.

Most peroxide systems have a neutralisation time of four to six hours. Some faster systems are ready in two to three hours, but this depends on the type of catalyst and the concentration of peroxide. It is important that you adhere to the specified time, as a neutralisation period that is too short can lead to a stinging sensation or irritation when you insert the lens.

You can tell whether neutralisation is complete by the colour of the liquid, if the system includes a colour indicator, or by the time that has elapsed. Some cases have a built-in timer or coloured ring that changes from red to green. Never insert the lens into your eye before neutralisation is complete.

Why is the neutralisation time important?

If you insert a lens before the peroxide has been fully neutralised, hydrogen peroxide will still come into contact with your eye. This can cause a sharp stinging sensation and irritate the surface of your eye. The neutralisation time is therefore not merely a suggestion, but a necessary waiting period before the lens can be worn safely.

Difference between systems

There are broadly two types of peroxide systems: one-step and two-step systems. With one-step systems, the catalyst is already in the container and neutralisation begins immediately as soon as you place the lens in the solution. With two-step systems, you add a neutralising tablet after a few hours. The neutralisation time depends on which system you are using, so always read the instructions for your specific solution.

What if you shorten the time?

Some people try to save time by removing the lens from the solution earlier than recommended. This is not a good idea, as the peroxide will not yet have been fully neutralised. Rinsing the lens with water does not help either, as water does not neutralise hydrogen peroxide. You should therefore always adhere to the minimum neutralisation time stated on the packaging.

Peroxide solutions at SMEYEL

At SMEYEL , you’ll find various peroxide solutions, each with its own neutralisation time and system. Always check the package leaflet before use, so you know how long you need to wait before you can safely wear the lens.