Wearing contact lenses beyond their recommended schedule poses a significant threat to eye health. “Too long” means exceeding the daily maximum wear time, typically 8 to 16 hours, as specified by the eye care professional or manufacturer. It also includes the habit of sleeping in lenses not approved for overnight or extended wear. Overwear disrupts the eye’s natural physiology, compromising the intricate balance of oxygen, lubrication, and cleanliness when the lens acts as a barrier for extended periods. This article explores the consequences of contact lens overwear, detailing the immediate discomfort and the severe, long-term conditions that can arise, along with prevention and emergency care steps.
Immediate Discomfort and Symptoms
The first signs of overwearing contacts are often mild and reversible, acting as the body’s warning system. A gritty or scratchy feeling, known as a foreign body sensation, indicates irritation of the corneal surface. This irritation is frequently accompanied by conjunctival hyperemia, which is the noticeable redness or bloodshot appearance of the eye.
Overwear causes the lens material to dry out and accumulate debris, disrupting the natural tear film. When the lens is less hydrated, it increases friction and discomfort because it no longer floats smoothly on the tear layer. This dryness can also cause temporary blurriness in vision as the irregular lens surface affects light entry.
These short-term symptoms are primarily a reaction to reduced oxygen supply and the accumulation of deposits on the lens surface. When lenses are promptly removed, the cornea regains direct access to oxygen, and comfort is often restored. However, persistent symptoms that do not resolve shortly after removal indicate potential tissue damage requiring professional attention.
Serious Eye Health Conditions
Prolonged contact lens wear causes oxygen deprivation in the cornea, which is the clear, dome-shaped front surface of the eye. The cornea normally receives most of its oxygen directly from the air. When a contact lens restricts this supply, a condition known as corneal hypoxia develops.
Hypoxia forces corneal cells to switch to anaerobic respiration, a less efficient process that produces lactic acid as a byproduct. This metabolic waste disrupts the fluid balance, causing water to be drawn into the tissue. The resulting swelling, or corneal edema, can lead to a cloudy appearance and blurred vision. Swelling exceeding 15% of the cornea’s normal thickness is considered pathological and threatens its transparency.
Chronic oxygen deprivation can trigger neovascularization, where new blood vessels grow from the white of the eye (sclera) into the clear cornea. The cornea is naturally avascular, and this invasion is a biological response to find an alternative oxygen source. If these vessels grow into the central visual axis, they can permanently compromise vision by blocking light.
A lack of oxygen also compromises the integrity of the corneal epithelium, the outermost protective layer, making the eye highly susceptible to infection. The lens can trap bacteria, fungi, and other microorganisms against the weakened surface. This combination can quickly lead to a severe infection called microbial keratitis, commonly known as a corneal ulcer.
Corneal ulcers are sight-threatening open sores that cause intense pain, light sensitivity, and permanent scarring. Even with treatment, the resulting scar tissue can leave a lasting opaque mark on the cornea, leading to irreversible vision loss. Another long-term consequence is Giant Papillary Conjunctivitis (GPC), an allergic reaction where small bumps, or papillae, form on the inner surface of the eyelids due to irritation from deposits that build up on the lens. GPC often makes continued lens wear intolerable until the condition is fully resolved.
Emergency Steps and Safe Wear Practices
If you have worn your contact lenses too long and are experiencing discomfort, gently remove them immediately. The eye needs relief from the oxygen-blocking barrier and trapped debris. Do not rub your eyes, as this can worsen any existing irritation or corneal abrasion.
If the eyes feel dry or irritated, applying preservative-free artificial tears can help soothe the surface and restore the natural tear film. Avoid using eye drops that claim to reduce redness, as these can mask the underlying problem and prevent you from recognizing the severity of the issue. If pain, severe redness, light sensitivity, or persistent blurred vision continues for several hours after lens removal, contact an eye care professional immediately, as these are signs of a developing infection or serious corneal damage.
Safe Wear Practices
Preventing contact lens overwear requires strict adherence to a prescribed routine:
- Never wear lenses longer than the maximum daily duration specified by your eye doctor.
- Never sleep in lenses unless they are specifically designed and prescribed for extended overnight wear, as eye closure drastically reduces oxygen transmission to the cornea.
- Always follow the manufacturer’s replacement schedule (daily, bi-weekly, or monthly), even if the lens still feels comfortable.
- Wash and dry hands thoroughly before handling lenses and never expose them to water, which can harbor harmful microorganisms.
- Regularly clean and replace your storage case at least once every three months to prevent the buildup of bacteria and biofilm.