Silicone Hydrogel Contact Lenses

Contact lenses consisting of silicone have some features that provide a healthy environment for the eye. These lenses are designed to allow as much as five to ten times the amount of oxygen to pass through to the cornea and eye, even during sleep, in comparison to lenses made from other materials.

Millions of people enjoy healthy contact lens wear on a daily basis. However, contact lenses are not risk-free. Severe, painful eye infections causing vision loss or blindness can occur. Contact lenses that allow higher levels of oxygen to pass to the eye could potentially reduce the risk of some complications.

Contact lens on a finger
Stevica Mrdja / EyeEm / Getty Images

Oxygen Deprivation Syndrome

Overwearing regular soft contact lenses can lead to a condition called oxygen deprivation syndrome. The condition causes red eyes and fluctuating vision.

Oxygen deprivation syndrome is a swelling in the cornea due to neovascularization, or new blood vessel growth, in the eyes. These abnormal blood vessels develop as the eye attempts to obtain oxygen to the cornea through blood flow instead of from the atmosphere where the cornea normally receives its oxygen.

The swelling leads to fluctuations in vision and can make it very difficult for an eye doctor to test vision during an eye exam.

Using silicone-based lenses often helps the signs and symptoms of oxygen deprivation syndrome to resolve quickly.

The current brands of silicone hydrogel lenses available, in order of highest oxygen transmissibility to lowest:

  • Air Optix Night & Day by Alcon
  • Air Optix Aqua by Alcon (enhances comfort for people who wear lenses daily)
  • Biofinity EW by Coopervision
  • Acuvue Oasys by Vistakon (designed to be more wettable than the others, beneficial for people who have dry eyes)
  • Ultra by Bausch and Lomb

There are also toric (astigmatism correcting) silicone hydrogel lenses on the market:

  • PureVision 2 Toric by Bausch and Lomb
  • Air Optix Aqua for Astigmatism by Alcon
  • Biofinity Toric by Coopervision

Research Doesn't Show Reduced Infection Risk

Silicone lenses have not been found to reduce the risk of bacterial keratitis for contact lens wearers. Current research suggests that contact lens-related infections may be caused by factors other than oxygen deprivation.

Factors include:

  • Tear film stagnation
  • Changes in the surface of the cornea
  • Slower turnover of corneal cells induced by contact lens wear

Oxygen transmission is a large factor, but may not be the only factor that contributes to infection. The type of lenses you wear, how long you wear them, and how well you take care of them all have an impact on these factors.

Contact Lens Infection Risk Factors

The single, largest risk factor for permanent vision loss due to contact lenses is wearing lenses overnight. Your risk for developing an infection is six to eight times higher if you sleep with your contact lenses in.

Other risk factors for developing serious eye infections include smoking, purchasing lenses via the internet, low socioeconomic status, improper cleaning, extended wearing times, and young age.

One UK study found that the infection risk varied significantly depending on the brand of contact lens. In this study, researchers looked at whether single-use, daily disposable contact lenses have a lower infection rate than two-week or monthly disposable lenses. Interestingly, daily disposable lens wearers had a 1.5 times higher risk of developing keratitis. However, the type of bacteria was less harmful. The organisms that caused the infections in daily disposable lens wearers were not as likely to cause severe vision loss.

A Word From Verywell

Silicone contact lenses can help prevent certain complications of contact lens wear. However, silicone lenses come with some risks. If overworn or not cleaned properly, these contact lenses can still cause problems. And some people cannot tolerate a silicone lens due to dryness, discomfort, or infiltrative keratitis due to overwear or reaction to the material. When considering contact lens materials, talk to your eye doctor about which types are compatible with your vision correction needs, and discuss the pros and cons of the options that are available to you.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Efron N, Morgan PB. Rethinking contact lens aftercare. Clin Exp Optom. 2017;100(5):411-431. doi:10.1111/cxo.12588

  3. Lowther GE. Considerations in Contact Lens Use Under Adverse Conditions: Proceedings of a Symposium. Washington, DC: National Academies Press (US); 1991.

  4. Bowden T, Lamb J. The History of Contact Lenses. Contact Lenses. 2019. doi:10.1016/b978-0-7020-7168-3.00045-3

  5. Stapleton F, Keay L, Edwards K, Holden B. The epidemiology of microbial keratitis with silicone hydrogel contact lenses. Eye Contact Lens. 2013;39(1):79-85. doi:10.1097/ICL.0b013e3182713919

  6. Corneal Infections Associated with Sleeping in Contact Lenses - Six Cases, United States, 2016–2018. Centers for Disease Control and Prevention. Aug 16, 2018.

  7. Dart JK, Radford CF, Minassian D, Verma S, Stapleton F. Risk factors for microbial keratitis with contemporary contact lenses: a case-control study. Ophthalmology. 2008;115(10):1647-54, 1654.e1-3. doi:10.1016/j.ophtha.2008.05.003

By Troy Bedinghaus, OD
Troy L. Bedinghaus, OD, board-certified optometric physician, owns Lakewood Family Eye Care in Florida. He is an active member of the American Optometric Association.