Silicone is a group of flexible, plastic materials that contain silicon, carbon and oxygen amongst other chemicals, while hydrogel is used for contact lenses as it retains a lot of moisture. When contact lenses are made with silicone hydrogel, they have a high oxygen permeability, allowing up to 5 times as much oxygen to reach the eye than traditional hydrogel lenses, while still retaining plenty of moisture. 

One reason silicone hydrogel contact lenses work so well is their adaptability. When they're dry, they're firm and hard but when they're introduced to moisture they soften and become flexible, making them fit comfortably and securely. 

There's often confusion between what is silicone and ‘silicon'. Silicon is one of the components in silicone, (as well as the name of a valley full of rich tech companies) but needs to be combined with other elements to create silicone. 

As silicone hydrogel is a popular material in modern contact lens manufacturing, silicone hydrogel contact lenses can correct a wide range of vision problems: 

• Myopia: Short-sightedness can be easily corrected with silicone hydrogel lenses, making it easy to see far away objects. 

• Hyperopia: Long-sightedness makes it tricky to focus on close objects and can be treated with silicone hydrogel contacts. 

• Astigmatism: If your eye has more of an elongated shape than a perfect sphere it can result in blurry vision and discomfort. Toric contact lenses are specially designed to fit securely, and many brands of toric lenses are made from silicone hydrogel. 

• Presbyopia: As you get older, your eye can struggle to focus on nearby objects, making reading tricky. Multifocal lenses provide a convenient solution to this problem, allowing you to focus on objects at all distances without needing to use glasses. Several brands of multifocal lenses are made from silicone hydrogel. 

As contact lenses cover a part of your eye, they reduce the amount of oxygen that can reach your cornea. If this amount is too low it can cause discomfort and, in extreme cases, a condition called hypoxia. As contact lens wear became more and more popular, silicone hydrogel contact lenses were introduced to help make wearing contact lenses for long hours more comfortable.

This also helped to make extended wear contact lenses safer, ensuring that this wearing pattern doesn't starve your eye of oxygen and keep your eyes feeling and looking healthy. This high level of performance makes silicone hydrogel contact lenses a great choice for those who work long hours or in dry or air-conditioned environments.

If you have been told by an eye doctor that you have hypoxia or have symptoms related to the condition, then silicone hydrogel lenses are most likely to be the right choice for you. Also, if you do find yourself wearing contact lenses for long hours, they'll help to prevent discomfort caused by the lack of oxygen reaching your eyes.

The most important thing to remember is that everyone's eyes are different. What works for one person might not work for another, and some people still find it more comfortable to wear soft hydrogel lenses. Which is better for you depends on how your eyes feel when you wear them and what your optician recommends as being the best option.

If you normally wear Boots’ own brand or Specsavers’ easyvision silicone hydrogel contact lenses, then you can still get your contact lenses online. These lenses have branded equivalents, and we've put together some tables so you can see what they are.

• See our Boots own brand equivalent contact lenses table

• See our Specsavers easyvision equivalent contact lens table

Silicone hydrogel daily contact lenses
There are a number of silicone hydrogel daily contact lenses available from the leading manufacturers. Products such as Dailies Total 1, Clariti 1 Day and everclear ELITE are all popular 1 day silicone hydrogel lenses that are among the most convenient and hygienic available. Daily lenses free you from the routine of cleaning and storing your contacts each night, providing crisp, clear vision every day with no hassle.

Silicone hydrogel monthly contact lenses
Monthly lenses provide great value for money as each pair lasts up to 30 consecutive days. All that you need to do is clean and store them in a multipurpose solution each night for perfect eyesight all day. CooperVision silicone hydrogel monthly lenses include Biofinity, Biofinity Toric and Avaira Vitality, which all make use of CooperVision's advanced technologies for high levels of comfort and performance.

Silicone hydrogel 2-weekly contact lenses
2-weekly contact lenses offer the great value of monthly lenses with a more regular replacement schedule of every fortnight, meaning that you can wear fresh lenses on a more frequent basis. Acuvue Oasys are popular silicone hydrogel lenses that can be worn for up to 14 consecutive days and are also available for other vision correction requirements: Acuvue Oasys for Astigmatism and Acuvue Oasys Multifocal.

Extended wear silicone hydrogel contact lenses
Because silicone hydrogel lenses are so breathable, they're often recommended by opticians for extended wear. Extended wear means you can keep your contact lenses on for anything between a week and 30 days without having to remove them, meaning that they don't need cleaning and can be slept in. If recommended by your optician, Air Optix Aqua Night & Day Aqua and Biofinity are silicone hydrogel lenses that are suitable choices for extended wear. Always make sure that your optician has approved your lenses for extended wear if you’re interested in wearing your contacts for longer.

Our most popular silicone hydrogel contact lenses

Acuvue Oasys

These 2-weekly lenses from Johnson & Johnson use Hydraclear Plus technology to keep your eyes moist throughout the day. Acuvue Oasys is designed with a smooth lens surface that prevents protein build ups that cause irritation in your eyes and UV blocking for an extra layer of defense from sun exposure.

Biofinity

Biofinity are one of CooperVision's most popular silicone hydrogel contact lenses and make use of Aquqaform™ technology to ensure that the optimum amount of oxygen can reach your eye. As monthly lenses they can be worn comfortably for up to 30 consecutive days.

Biofinity Toric

Biofinity Toric monthly contact lenses for astigmatism are designed to retain moisture and allow oxygen through for a healthy and comfortable feel. Their toric design also means that they will fit your eyes securely and provide consistently clear vision for the entire time that you're wearing them.