Hydrogel vs silicone hydrogel contact lenses: benefits & disadvantages
Every contact lens wearer – especially those who are affected by dry eye syndrome, or digital eye strain – at some point faces the question: “What’s the best material for contact lenses?”
- “How important is water content in contact lenses?”
- “Shall I choose hydrogel or silicone hydrogel lenses?”
- “Which material is the best for my delicate eyes?”
We receive your enquiries on a daily basis, so we decided to address them in this article, to make things a bit clearer for you.
What type of soft contact lenses are there?
Nowadays most contact lenses are either made of hydrogel or silicone hydrogel.
Hydrogel contact lenses
Hydrogel lenses are made from gel-like, water-containing plastics called hydrogels. These lenses are very thin and pliable and conform to the surface of the eye.
Introduced in the early 1970s, hydrogel lenses made contact lenses much more popular, thanks to the improved comfort and ease of use.
When it comes to dry and delicate eyes, hydrogel material – thanks to its unique biocompatibility with the human eye – is quite often the most suitable choice.
A recent study that compared hydrogel lenses to silicone hydrogel lenses 1 reported that, in some subjects, there's a connection between the presence of silicone and the rise of eye allergies.
The disadvantage of hydrogel lenses appears when the water gradually evaporates (e.g. after many hours of wearing, or when in challenging environments) making the material less comfortable.
- Great comfort and durability
- Highly biocompatible with the human eye
- Suitable for delicate eyes
- Lower oxygen permeability
- Less comfortable after many hours of wearing
- Less elastic than silicone hydrogel
Silicone hydrogel contact lenses
Silicone hydrogel lenses are an advanced type of soft contacts that are more porous than regular hydrogel lenses and allow even more oxygen to reach the cornea. Introduced in 2002, it's a combination of hydrogel and silicone in which is possible for the manufacturer to increase the oxygen permeability, even with a low volume of water. Modern silicone hydrogel lenses offer the advantage of a higher oxygen transmissibility, which reduces the risk of eye hypoxia2. This feature makes them a great choice for extended wear. The disadvantage of these lenses, however, is the lower level of wettability and tendency to collect more deposits.
- High oxygen permeability
- Reduce hypoxia-related symptoms
- Allow extended wear
- Less comfortable on delicate eyes
- Collect more deposits
- Not suitable for silicone intolerants
In conclusion, what’s the best material for contact lenses?
As we like to stress to our customers, there is no such thing as “the best contact lens material on the market”. It's a matter of finding the best option for your own eyes.Speaking again of the differences between hydrogel and silicone hydrogel,
Neither material types showed superiority in comfort and adverse event rates were low with both material types. These findings suggest that the choice of material depends entirely on the agreement between practitioner and patient3.
First rule, as always, is to discuss the matter with your eye doctor. As much as each model of contact lenses has different features, every eye is different and therefore has different necessities. And, of course, one of the most important parameters to consider when choosing quality contact lenses is precisely the water content. Water moisturizes the lenses, it makes them softer and more comfortable to wear.
Let’s talk about water content in contact lenses
Depending on water content, contact lenses can be divided into three groups. Each group holds a slightly different quality. Do you know which group your contacts belong to?
- Low water content (up to 45%) – silicone hydrogel contact lenses, usually intended for continuous wear. They have almost 100% oxygen permeability.
- Mid water content (up to 60%) – hydrogel contact lenses, suitable for most users.
- High water content (up to 90%) – hydrogel contact lenses for more sensitive eyes.
Water Content and Oxygen transmissibility (Dk/t)
As you can see in the chart below, the ratio of permeability of your lenses depends directly on their water content.
The higher the water content, the more difficult it is for oxygen to get to the cornea where the surface is dependent on atmospheric oxygen. And it works the other way around: the more the material is permeable to oxygen, the less water can bind to it.
So, if your contacts are moist, they will surely be comfortable and easy to apply.
But remember that water gradually evaporates from your contacts during the day.
If this occurs, your eyes could become dry.
Discomfort may occur, and you may get itchiness and burning sensation. This is why a lot of contact lens users think that the more water, the better for their eyes.
As a matter of fact, though, moisture is not the only thing our eyes need to stay healthy. Our eyes need to breathe. This is why it’s always important to use the help of an ophthalmologist, when choosing the right contacts. Wettability and breathability are both equally important. It’s a matter of balance.
If what's written above sounds just “too theoretical”, have a look at the next chart.
Chart of Contact Lenses According to their Water Content and Oxygen transmissibility (Dk/t)
Here you can see some of the most popular contact lenses on the market and their wettability/transmissibility ratios. As a contact lens wearer, you might have experience with one or more of these lenses. Here you can easily compare their features. From theory to practice!
Bestselling hydrogel contact lenses
Lenjoy 1 Day Comfort (30 lenses)
Lenjoy 1 day Comfort contact lenses offer amazing visual performance, long-lasting wearing comfort and optimum health for the eyes thanks to their aspheric design. Biologically compatible hydrating technology, non-slip surface, UV radiation protection and light-blue tint for easier manipulation are the main features of these lenses. Made with Omafilcon, currently one of the most suitable materials for dry eye syndrome, according to doctors.Lenjoy 1 Day Comfort
Bestselling silicone hydrogel lenses
1-DAY Acuvue Moist
1-Day Acuvue Moist are daily disposable contact lenses that provide amazing comfort and freshness all day long thanks to their moisture lock technology that makes them easy and comfortable to wear.1-DAY Acuvue Moist lenses
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