Contact lens discomfort (CLD) is a common experience, affecting up to half of all contact lens wearers at some point. Any pain while wearing lenses signals a physical or environmental mismatch. This sensation, ranging from mild awareness to sharp pain, indicates reduced compatibility between the lens and the delicate ocular environment. The causes of contact lens pain generally fall into three main categories: issues with the lens itself, the physiological state of the eye, or a serious health complication.
Common Causes Related to Fit and Use
Wearing contact lenses longer than prescribed often causes corneal hypoxia. The cornea receives oxygen primarily from the air and tears. When a lens remains on the eye too long, it forms a barrier that reduces this oxygen supply. This deprivation can cause the cornea to swell (edema), leading to discomfort, redness, and a burning sensation.
Sleeping in lenses not approved for extended wear exacerbates hypoxia, as the closed eyelid already reduces oxygen access by 50 to 90 percent. Over time, this lack of oxygen can damage the corneal surface, making it vulnerable to abrasions and infection. Furthermore, a lens that does not fit correctly, whether too tight or too loose, causes mechanical irritation. A tight lens restricts the movement needed for tear exchange, leading to dehydration and poor oxygen flow.
Improper cleaning and storage routines allow deposits to accumulate, causing painful issues. Proteins and lipids naturally present in the tear film adhere to the lens surface. If these deposits are not removed through proper cleaning, the lens becomes rough and cloudy, causing friction with the eyelid. Using expired or incompatible lens solutions can fail to adequately disinfect the lens, allowing microorganisms to thrive. “Topping off” old solution with new solution also dilutes the disinfectant, increasing the risk of irritation and infection.
Physiological and Environmental Factors
The interaction between a contact lens and the eye’s natural tear film is easily disrupted, often resulting in Dry Eye Syndrome symptoms. The lens rests on the tear film, separating it into pre-lens and post-lens layers. This division increases the rate at which the tear film evaporates, leaving the eye feeling gritty and dry. For those with chronic dryness, contacts can absorb existing moisture, further destabilizing the tear layer and intensifying discomfort.
The surrounding environment contributes to contact lens dryness and irritation. Low-humidity environments, such as those created by air conditioning, heating, or high altitudes, accelerate tear film evaporation from the lens surface. This rapid moisture loss causes the lens material to dehydrate, increasing friction and creating a foreign body sensation. Exposure to airborne irritants, like dust, smoke, or chemical fumes, can also cause particles to become trapped under the lens.
Giant Papillary Conjunctivitis (GPC) is an inflammatory reaction of the inner eyelid. GPC is often triggered by an immune response to protein deposits on the lens or a sensitivity to solution preservatives. The chronic irritation causes the normally smooth inner surface of the upper eyelid to develop small, raised bumps called papillae. These enlarged papillae rub against the lens with every blink, leading to itching, excessive mucus production, and lens intolerance.
Warning Signs and Immediate Action
While minor discomfort can often be resolved with changes to wear schedule or hygiene, certain symptoms signal a serious medical issue requiring immediate attention. Sudden, severe, or debilitating eye pain should prompt the immediate removal of the contact lens. If this pain persists after removal, it may indicate a corneal abrasion (a scratch on the eye’s surface) or a corneal ulcer.
Other acute symptoms include significant redness that does not improve within a few hours, or any discharge that is thick, yellow, or greenish. Sensitivity to light (photophobia) and any sudden blurring or reduction in vision are also important signs. These symptoms, particularly when combined, can indicate an infection such as microbial keratitis. This corneal infection can progress rapidly and lead to permanent vision loss if not treated quickly.
The protocol for any severe or persistent symptom must be followed without delay. Remove the contact lenses immediately and do not attempt to reinsert them. Do not try to treat the problem with over-the-counter drops or rewetting solutions, as this may mask symptoms or introduce contaminants. Contact an eye care professional immediately for an emergency examination to determine the cause and begin appropriate treatment.