Hydrogel lenses

Hydrogel lenses are soft contact lenses made from a synthetic material that absorbs and retains water. The material consists of polymers that are hydrophilic, meaning they attract water. This water content ensures the lenses remain soft and flexible on your eye.

The water content in hydrogel lenses usually varies between 38 and 75 per cent. This water plays an important role in oxygen supply: oxygen dissolves in the water and thus reaches your cornea. The higher the water content, the more oxygen can, in principle, be allowed to pass through, but also the faster the lens can dry out.

Hydrogel lenses were the first soft contact lenses to come onto the market, in the 1970s. They are still widely used, particularly for daily disposable lenses and short-term wear. For people who wear lenses all day or have sensitive eyes, silicone hydrogel lenses are now also available; these allow more oxygen to pass through via the silicone rather than just through water.

Material and properties

The base material of hydrogel lenses consists of polymers such as HEMA (hydroxyethyl methacrylate) or similar substances. These polymers form a network that retains water molecules. Their soft, flexible nature makes hydrogel lenses comfortable to wear, especially at first.

As the material contains water, it is important that hydrogel lenses remain moist at all times. Dry environments, air conditioning, screen time or prolonged wear can cause the water in the lens to evaporate. The lens then draws moisture from your tear film, which can lead to a dry sensation.

Oxygen permeability

Your cornea needs oxygen to stay healthy. With hydrogel lenses, this oxygen comes from the air, dissolves into the water in the lens and thus reaches your cornea. The amount of oxygen that is allowed through depends on the water content and the thickness of the lens.

For short-term wear, such as a few hours a day, hydrogel lenses provide sufficient oxygen. For long-term or daily wear of more than eight hours, opticians often recommend silicone hydrogel lenses, as these allow more oxygen to pass through without relying on their water content.

Who are hydrogel lenses suitable for?

Hydrogel lenses are often chosen for occasional use, for example for sport, a night out or if you want to take a break from your glasses now and then. They are also popular as daily disposable lenses, as you throw them away after a single use and therefore they require no maintenance.

If you wear lenses all day, for example for eight hours or more, you may find silicone hydrogel lenses more comfortable. They allow more oxygen to pass through and are less likely to dry out. Your optician can advise you on which type best suits your wearing pattern and eyes.

Maintenance and care

Reusable hydrogel lenses, such as two-week or monthly lenses, need to be cleaned daily and stored in fresh solution. Proteins, fats and other deposits from your tear film can build up on the lens surface. Proper care helps to keep the lenses clear and comfortable.

At SMEYEL , you’ll find lens solutions and care products suitable for hydrogel lenses, such as all-in-one solutions or peroxide systems. Always follow the instructions for use provided with your solution and replace your lens case regularly.

Difference from silicone hydrogel

Silicone hydrogel lenses contain silicone as well as the water-absorbing polymer. Silicone allows oxygen to pass through much more effectively than water, making these lenses suitable for extended wear and sometimes even for overnight wear (only on the advice of your optician or ophthalmologist).

Silicone-free hydrogel lenses are often thinner, softer and may feel more comfortable at first. They are also often cheaper. The main difference lies in oxygen permeability: silicone hydrogel lenses score higher in this respect, whilst hydrogel lenses are sufficient for shorter wearing times.

Tips for comfortable wear

• Do not wear your lenses for longer than the recommended time; for most hydrogel lenses, this is a maximum of eight to ten hours a day.
• Keep your hands clean and dry before inserting or removing your lenses.
• Only use fresh lens solution and never reuse old solution from your lens case.
• Do your eyes feel dry whilst wearing them? Moisturising eye drops can help to rinse the surface of the eye and maintain comfort.
• Are you experiencing irritation, redness or blurred vision? Remove your lenses and have your eyes examined by your optician or ophthalmologist.