The feeling of a contact lens constantly slipping, moving, or feeling loose instead of adhering smoothly to the eye can be frustrating. When working correctly, a contact lens should float gently on the tear film, remaining centered over the cornea without noticeable movement. The feeling that your lens is not “sticking” indicates a disruption in the delicate balance between the lens, the eye’s surface, and the surrounding environment. This common issue points to several distinct problems, ranging from incorrect physical measurements and poor hygiene to underlying biological or environmental factors. Understanding the specific cause is the first step toward achieving comfortable, stable contact lens wear.
Physical Issues with Lens Fit and Orientation
The most immediate cause of a non-adhering lens is a physical mismatch between the lens and the eye’s unique shape. Contact lenses are precision medical devices defined by two measurements: the base curve (BC) and the diameter (DIA). The base curve specifies the curvature of the lens’s inner surface, designed to match the specific curve of your cornea. If the base curve is too flat, the lens will move too much, causing slippage or even falling out. Conversely, a curve that is too steep can grip the eye too tightly, leading to discomfort and an unstable fit.
If the diameter is incorrect, the lens will not center properly, leading to excessive movement and fluctuating vision. Determining the correct BC and DIA requires a professional measurement called keratometry to ensure proper alignment. Inserting the lens inside out is a simpler, common issue that immediately prevents proper adhesion.
A correctly oriented soft lens will look like a perfect cup with smooth, upright edges when placed on a fingertip. If the edges flare outward, resembling a soup bowl with a rim, the lens is inverted and will feel unstable and uncomfortable. You can also perform the “taco test” by gently folding the lens between your thumb and forefinger; if the edges fold inward like a taco shell, the lens is correct.
Environmental Factors Affecting Adherence
The stability of a contact lens relies on a healthy tear film, which is composed of water, mucus, and a lipid (oil) layer. When the tears evaporate too quickly or lack the correct components, the lens loses the necessary surface tension to float correctly, leading to excessive movement and a feeling of looseness. This condition is frequently linked to dry eye syndrome, where the quantity or quality of tears is compromised.
The tear film’s components naturally accumulate on the lens surface as deposits, altering the lens’s ability to adhere smoothly. Proteins, such as lysozyme, can bind to the lens material and become rough, while lipids create a greasy film that promotes slippage. These deposits change the lens curvature and surface wettability, making it difficult for the lens to remain centered.
Low-humidity environments, such as those created by air conditioning or heating systems, increase tear evaporation and lead to a drier lens surface. Furthermore, certain systemic medications can reduce the natural production of aqueous tears, exacerbating dry eye. These medications include antihistamines, beta-blockers, and some diuretics.
Hygiene and Maintenance Errors
External contaminants compromise the lens surface and prevent smooth adherence. Makeup is a common culprit, especially products containing oils, waxes, or silicones like waterproof mascara. These substances easily transfer to the lens, creating an oily film that drastically reduces wettability and causes the lens to repel the eye’s surface.
Hand hygiene is also a frequent source of error, particularly the use of moisturizing or creamy hand soaps before lens handling. The residue from these soaps, designed to leave a moisturizing film on the skin, transfers directly to the lens and creates a non-adhering barrier. It is important to use a plain, non-moisturizing soap and rinse hands thoroughly to remove all residue before touching the lenses.
The solutions used for cleaning and storage can also undermine lens adhesion. Never use tap water or saliva to rinse or store lenses, as they contain microorganisms and lack the necessary saline balance, which can cause the lens to swell or change shape. Additionally, “topping off” old solution or using expired solution fails to properly disinfect the lens. This allows the rapid accumulation of deposits, leading to poor comfort and adherence.
When to Consult an Eye Doctor
If self-corrective measures like checking the lens orientation and improving hygiene do not resolve the issue, professional intervention is necessary. The problem may be an incorrect fit, which only an eye care professional can diagnose by measuring your eye’s precise base curve and diameter. They can perform a contact lens refitting, which might involve prescribing a different lens material or design better suited to your tear chemistry and eye shape.
You should seek immediate care if the lens movement is accompanied by severe eye pain, persistent redness, a sudden change in vision, or extreme sensitivity to light. These symptoms can indicate a more serious underlying issue, such as a corneal abrasion from a damaged lens or an infection. A doctor can also diagnose chronic conditions like severe dry eye disease or giant papillary conjunctivitis (GPC), which require specific medical treatments beyond simply switching lens brands.