Yes, there are contact lenses designed for extended wear, some approved for continuous use for up to 30 days and nights. This type of lens offers significant convenience by removing the need for daily cleaning and handling, but it requires strict adherence to safety and hygiene protocols. The ability to wear a lens for an entire month depends on the lens material and specific regulatory approval, determined in consultation with an eye care professional.
What Makes Monthly Lenses Different
The ability for a contact lens to be worn for extended periods, especially while sleeping, is a direct result of advancements in material science. Traditional soft lenses, known as hydrogels, are made primarily of water and plastic, which do not allow sufficient oxygen to pass through to the cornea when the eyelid is closed. When the eye is shut, the cornea receives oxygen only from the blood vessels in the inner eyelid, and a low-oxygen lens material can significantly block this supply.
Modern monthly extended-wear lenses are typically made from silicone hydrogel, which incorporates silicone into the lens structure. Silicone is highly effective at transmitting oxygen, allowing for a much greater flow to the cornea, even during sleep. This high oxygen transmissibility, measured by the Dk/t value, enables these lenses to be worn safely overnight for up to 30 continuous nights. The increased oxygen flow essentially eliminates hypoxia-related complications, such as corneal swelling, common with older extended-wear lenses.
Essential Rules for Wearing Extended Lenses
Wearing monthly lenses safely requires following the specific schedule prescribed by an eye care professional. These schedules generally fall into two categories: continuous wear and flexible wear. Continuous wear means the lens is worn 24 hours a day for the full approved period (up to 30 consecutive nights), after which the lenses must be discarded and replaced with a fresh pair.
Flexible wear is a modality where the lenses are worn daily but can occasionally be worn overnight, such as for a weekend, before being removed, cleaned, and stored. The maximum replacement schedule for a monthly lens is 30 days from the day the package is opened. Exceeding this limit, even if the lenses feel comfortable, significantly increases the risk of complications due to deposit buildup and material degradation. Regular eye examinations, typically every six months, are necessary to ensure eye health remains stable while wearing the lenses.
Proper Cleaning and Storage Protocols
Strict cleaning and storage practices are necessary, even if the lens is approved for continuous wear and must be removed occasionally. For those on a flexible wear schedule, lenses must be removed nightly or every few days and undergo a thorough “rub and rinse” cleaning process. The lens should be placed in the palm of a clean hand, solution applied, and gently rubbed with a finger for several seconds before being rinsed.
The storage solution must always be fresh; wearers should never simply “top off” the old solution in the case, as this reduces disinfecting power and can harbor microorganisms. Use only the multipurpose or hydrogen peroxide solution specified for the lenses, as water or saline does not properly disinfect. The lens case is a common source of contamination and should be rinsed with fresh solution, allowed to air-dry, and replaced entirely every three months.
Increased Risks and When to Seek Help
While modern silicone hydrogel materials have reduced the risk of oxygen deprivation, wearing any lens overnight still carries a higher risk of adverse events compared to daily disposable lenses. One serious risk is microbial keratitis, a sight-threatening corneal infection. This risk is estimated to be several times higher for extended-wear users than for daily-wear users.
Other complications include giant papillary conjunctivitis (GPC), an allergic inflammation on the inner eyelid often caused by protein deposits on the lens surface. Chronic, low-level oxygen deprivation can lead to corneal neovascularization, where new blood vessels grow into the clear cornea seeking oxygen. Any persistent symptoms like noticeable pain, excessive eye redness, sudden blurred vision, or extreme sensitivity to light require immediate attention. These warning signs mean the lens should be removed, and an eye care professional should be consulted immediately.