water content in coloured contact lenses

Water content is the amount of water present in contact lenses. Coloured contact lenses are made from a water loving plastic called “hydrogels” that is responsible to keep the lenses soft in your eyes. The higher the water content, the higher is the oxygen permeability. This makes high water content coloured contact lenses more appropriate for longer wear or extended wear contacts. However, high water content does not always translate into higher oxygen permeability unless they are “Silicone hydrogel”. Confused? Continue reading the below to broaden your understanding towards water content.

Are High Water Contacts Good for Me?

You might get into thinking that high water coloured contacts are generally better as they allow more oxygen to eyes. Unfortunately, the more the water content, the sooner they will dry your eyes. Since they are made from hydrogel material that absorbs water from its surroundings, they are not considered good for patients with dry eyes despite them being very comfortable in eyes.

Unfortunately high water content does not always translate into high oxygen permeation (the DK value). DK value is the amount of oxygen that pass through the material under the given circumstances. Since contacts lenses block transmission of oxygen partially, they may lead to a medical condition “Hypoxia”.

What are Silicone Hydrogel Coloured Contact Lenses?

Silicone hydrogel coloured contact lenses are the type of contacts that are made from an advanced material. They aim to decrease the risk of infections caused by hypoxia. The hybrid of silicone and hydrogel material allows more oxygen to eyes while preventing them from dehydration. While hydrogel absorbs water, silicone material is hydrophobic or water repelling. Silicone is also responsible for higher oxygen transmission to the eyes. As a result, you get contact lenses that do not only allow higher oxygen transmission but are also able to lock in more moisture.

What should be the Water Content of Ideal Contact Lenses?

Coloured contact lenses are available in three categories. High water content, medium and low. High water content are above 75% whereas medium is above 50% while low water content is anything below 40%. Consult your doctor to determine which material of coloured contact lenses will do the best for you.

The bottom line:

Generally, most people will do fine with high water content lenses which means more oxygen. Ironically, these type of lenses are infamous to making your eyes drier as they tend to wick away the moisture from your eyes. People need to use rewetting drops to keep eyes moist and lenses hydrated. On the other hand silicone hydrogel coloured contact lenses allow 5 times more oxygen, retain more water & resist bacteria accumulation that make them ideal for extended wear.