Contact lenses are medical devices requiring strict adherence to manufacturer and eye care professional guidelines. Wearing lenses far beyond the recommended schedule, especially never removing them, introduces continuous stress on the eye’s delicate biology. This practice disrupts the cornea’s natural functions and creates an environment where serious, vision-threatening complications can develop rapidly. The potential consequences range from chronic discomfort to severe, sight-impairing infections.
Oxygen Deprivation and Corneal Swelling
The cornea, the clear front surface of the eye, lacks blood vessels and must draw its oxygen directly from the surrounding air and tear film. A contact lens acts as a physical barrier, significantly reducing this oxygen flow, leading to hypoxia. When the lens is never removed, this deprivation becomes chronic, forcing the cornea to rely on anaerobic respiration. This shift causes a buildup of lactic acid and other waste products, drawing water into the cornea and resulting in swelling, or edema. Chronic edema can cloud the cornea, causing blurry vision and discomfort, and weakens the cornea’s outermost layer, the epithelium.
The Threat of Microbial Keratitis
The most devastating consequence of continuous overwear is microbial keratitis, a severe corneal infection often called a corneal ulcer. The combination of a weakened epithelial barrier and the lens trapping debris sets the stage for infection, allowing bacteria, fungi, or parasites to multiply rapidly. Pseudomonas aeruginosa is the most common culprit in bacterial keratitis, capable of causing significant corneal damage within 24 hours. A severe threat is Acanthamoeba keratitis, a parasitic infection linked to exposure to tap water or swimming while wearing lenses. These infections lead to painful inflammation and corneal ulcer formation, which can quickly scar the transparent cornea, resulting in permanent vision loss or the need for a corneal transplant if not treated immediately.
Structural Changes from Chronic Overwear
Beyond acute infection, never removing contact lenses leads to long-term structural alterations in the ocular tissues. One change is corneal neovascularization, where the cornea, desperate for oxygen, signals nearby blood vessels to grow into its transparent tissue from the limbus. This invasion compromises the cornea’s clarity and can lead to permanent vision impairment if the vessels reach the central visual axis. Another chronic condition is Giant Papillary Conjunctivitis (GPC), an inflammatory reaction where the inner surface of the upper eyelid develops large bumps called papillae. GPC is an immune response to irritation and protein deposits on the lens surface, causing a foreign body sensation, itching, and excessive mucus discharge.
Recognizing Symptoms and Safe Wear Guidelines
Symptoms that signal a potential problem include persistent redness, unusual pain or soreness, and sudden blurring of vision. Increased sensitivity to light (photophobia) and excessive tearing or discharge are also strong indicators of a developing issue. If any of these symptoms appear, the contact lenses must be removed immediately and discarded. Never attempt to self-treat with over-the-counter drops, as this can mask symptoms or worsen an underlying infection; contact an eye care professional immediately, as a severe infection requires emergency treatment. To prevent complications, always adhere to the prescribed wear schedule, which involves daily removal, cleaning, and disinfection, and replace the storage case every three months.