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An Extended Wear (EW) lens is a contact lens specifically approved by the regulatory bodies (like the FDA) to be worn continuously for multiple days and nights without removal. This lens is designed for maximum oxygen permeability.
read more about extended wear lens ...The primary material used for extended wear is silicone hydrogel. This material is highly porous, allowing up to five times more oxygen to reach the cornea than older hydrogel lenses, which is necessary to prevent severe swelling and corneal damage during sleep.
The regulatory standard requires the lens material to have a very high oxygen transmissibility rate (Dk/t) to be approved for overnight use. This high rate is needed because the closed eyelid already reduces the eye's oxygen supply.
The main safety guidelines state that the maximum approved wear time (usually 6 nights/7 days or 29 nights/30 days) should never be exceeded. The lenses must be removed and cleaned as directed by the eye doctor to prevent protein buildup and infection.
Sleeping in contact lenses greatly increases the risk of serious eye infection, making careful hygiene and strict adherence to the replacement schedule very important. Ignoring the wear schedule can lead to corneal ulcers.
Continuous wear affects eye health by mildly reducing the oxygen available to the cornea, even with silicone hydrogel. This chronic low-grade hypoxia can rarely cause blood vessels to grow into the cornea (neovascularization), which severely threatens vision. Regular exams are needed to monitor for this condition. The lens must be removed immediately if any redness or discomfort is felt.
Diagnosis for suitability relies on a extensive eye exam. The eye doctor assesses the health of the cornea and tear film. Patients with dry eye or active allergies are often deemed unsuitable for continuous wear due to the increased risk of complications.
The difference is the approved duration of use. Daily wear lenses must be removed every night. Extended wear lenses have regulatory approval for occasional or continuous overnight use due to their superior oxygen permeability.
No, only lenses specifically labeled and approved for extended wear (EW) should ever be worn overnight.
Yes, sleeping in any contact lens significantly increases the risk of serious eye infections, including corneal ulcers.
The maximum duration is set by the specific brand and the eye doctor, typically 6 nights or up to 30 nights.
If you wear extended-wear lenses and your eye becomes red, painful, or you see a "white spot" on your cornea, seek emergency care immediately. This could be a "Microbial Keratitis" (corneal ulcer). Extended wear requires more frequent checkups to ensure your cornea is receiving enough oxygen.
CDC. Contact Lens Wear and Care (cdc.gov). 2024.
FDA. Contact Lenses: Risks and Safety (fda.gov). 2024.
AAO. Extended Wear Contact Lenses (aao.org). 2024.
AOA. Contact Lens Safety (aoa.org). 2024.