Contact lenses are medical devices placed directly on the surface of the eye to correct vision. Adhering to the manufacturer’s and your eye care professional’s instructions for wearing time is essential for maintaining eye health. The duration a person can safely wear lenses each day is determined by the complex needs of the cornea and the physical limitations of the lens material. Wearing lenses beyond the recommended schedule can lead to discomfort, irritation, and potentially serious complications.
Recommended Safe Wearing Times
For soft daily-wear lenses, the general guideline for safe use is a maximum of 8 to 16 hours per day. This range depends on the specific lens material, the individual wearer’s tear production, and environmental factors like air quality and humidity. Modern silicone hydrogel lenses, designed for high oxygen flow, may allow for the upper end of this range.
These lenses must be removed before going to sleep, as they are not approved for overnight use. New wearers are often advised to begin with a shorter wearing time, gradually increasing the duration as their eyes adapt. The most reliable schedule is the one established by an eye care professional, considering personal eye health history and lens type.
Physiological Factors Limiting Wear
Contact lenses cannot be worn indefinitely because of the health requirements of the cornea, the clear front dome of the eye. The cornea lacks blood vessels and must draw its oxygen directly from the air. When a contact lens covers the cornea, it acts as a barrier, reducing oxygen flow.
Prolonged wear can lead to corneal hypoxia (oxygen deprivation), causing the cornea to swell and impair its function. The lens also disrupts the eye’s natural tear film, which lubricates, cleans, and protects the surface. The presence of the lens makes the tear film thinner, less stable, and prone to increased evaporation. Furthermore, the lens surface attracts deposits from the tear film, primarily proteins and lipids, which accumulate over time. This buildup increases friction with the eyelid, contributing to discomfort and irritation. These biological stresses necessitate a strict daily wearing limit.
The Critical Difference: Daily vs. Extended Wear
The wearing schedule for a contact lens is defined by its intended use, creating a distinct difference between daily wear and extended wear lenses.
Daily Wear Lenses
Daily wear lenses are designed to be inserted in the morning and removed and discarded before sleep, ensuring a fresh, sterile lens is used daily. This single-day use eliminates the need for cleaning and storage, which significantly reduces the risk of infection and deposit-related irritation. Daily disposable lenses are often recommended as the preferred option for most users due to their superior hygiene profile.
Extended Wear Lenses
Extended wear (EW) lenses are manufactured from highly permeable materials, such as silicone hydrogel, allowing a greater amount of oxygen to pass through to the cornea. This increased oxygen flow permits continuous wear, including while sleeping, for a set number of days. Depending on the professional’s recommendation, EW lenses may be approved for up to seven days of continuous wear, with some advanced types permitted for up to 30 days before mandatory removal. However, the convenience of extended wear comes with a heightened risk, as wearing any contact lens overnight increases the chance of developing serious eye infections. Continuous wear requires strict adherence to a professional’s schedule and careful monitoring for irritation or infection.
Recognizing and Responding to Overwearing Symptoms
If the recommended wearing time is exceeded, the eyes will signal distress through common symptoms of contact lens overwear syndrome.
Symptoms of Overwear
- Noticeable eye redness.
- A persistent feeling of dryness or grittiness.
- Increased sensitivity to light (photophobia).
- Blurred or fluctuating vision, excessive tearing, or pain.
The immediate action upon noticing any of these symptoms is to remove the contact lenses immediately. The eye needs a period of rest to recover from stress and oxygen deprivation. If symptoms are mild, allowing the eyes to rest and using preservative-free lubricating drops may be sufficient. If discomfort, redness, or blurred vision persists for more than 24 hours after removal, consult an eye care professional to rule out infection or corneal damage.