Contact lens discomfort that is limited to a single eye, such as the left, is a common experience. This unilateral irritation suggests a localized issue that can usually be resolved by systematically checking both the lens and the eye itself. The source of the problem is often a simple physical or environmental factor, but it can also signal a more serious underlying eye health condition. Understanding the distinct categories of potential causes provides a practical checklist for troubleshooting this localized irritation.
Issues Related to the Contact Lens Itself
The physical state of the contact lens designated for the left eye is frequently the source of localized discomfort. Even a microscopic tear, chip, or jagged edge along the lens periphery can cause a constant foreign body sensation against the delicate corneal or conjunctival tissue. Remove the lens immediately and inspect it closely for any signs of damage. A lens that has been accidentally warped, perhaps by being squeezed in its case or exposed to high heat, may not sit correctly on the eye, causing poor fit and irritation.
Another common mechanical issue is lens inversion, where the lens is placed on the eye inside out. This causes the edges to flare out slightly, leading to a noticeable awareness or feeling of something in the eye. Furthermore, the lens surface can accumulate debris, such as fine dust, airborne allergens, or makeup residue, which can become trapped and cause irritation, stinging, and redness. Over time, natural tear components like proteins and lipids can build up on the lens, creating a rougher surface that interferes with tear film stability and leads to chronic discomfort.
Problems Originating from the Left Eye
Sometimes, the left eye itself develops a localized issue that makes it intolerant to contact lens wear. One of the most frequent causes is localized ocular dryness, which occurs when one eye produces less stable tears than the other, causing the lens to dry out and rub against the cornea. This dryness can be exacerbated by environmental factors like air conditioning or prolonged screen time, which reduce the natural blink rate.
An uncomfortable sensation often described as grittiness or a scratchy feeling can be caused by a tiny foreign body, like an eyelash or a speck of dirt, trapped under the lens. This foreign object constantly scrapes against the corneal surface with every blink. More serious conditions include a corneal abrasion, which is a scratch on the eye’s clear front surface, or a localized infection like keratitis or conjunctivitis. Since each eye is unique, minor differences in shape or tear production between the left and right eyes can also lead to a poor fit for the left lens, making it feel uncomfortable.
Errors in Lens Handling and Care
User habits and hygiene practices represent a significant and controllable source of unilateral discomfort. Improper handwashing before handling the left lens can transfer oil, dust, and microorganisms directly onto its surface, causing immediate irritation or contamination. Contamination often begins in the lens case, particularly if the left side is not cleaned or replaced regularly.
A common mistake is “topping off” the old solution in the lens case instead of discarding it and using a completely fresh, sterile solution. This practice dilutes the disinfectant, allowing bacteria and fungi to thrive in the case, which then transfer to the lens and the eye. Using tap water to rinse or store contacts is also hazardous, as water can harbor microorganisms like Acanthamoeba, which can lead to severe eye infections. Finally, accidentally switching the lenses, if the left and right eyes have different prescriptions, can cause visual strain and discomfort.
When Discomfort Requires Professional Attention
While many causes of lens discomfort are minor, certain symptoms indicate a problem that requires immediate consultation with an eye care professional. Remove the lens and seek prompt medical advice if you experience sudden, severe, or sharp eye pain. Persistent discomfort that continues for more than a few hours after removing the lens and switching to a fresh pair is also a warning sign.
Other symptoms that necessitate urgent evaluation include significant changes in vision, such as sudden blurring or fogginess, or extreme sensitivity to light, known as photophobia. Any noticeable discharge from the eye, whether watery or mucous, or redness that worsens or does not improve after removing the contact lens, should also be treated as a possible infection or serious injury. These symptoms suggest potential issues like a corneal ulcer or infection that could lead to lasting damage if not treated quickly.