The idea that a contact lens could simply dissolve away in the eye’s natural fluids is a common concern for many wearers. The simple and reassuring answer is that modern contact lenses are specifically engineered to prevent this from happening. They are not made of water-soluble materials and remain physically intact within the eye’s environment. Understanding the science behind the lens material and the anatomy of the eye helps explain why a misplaced lens will not disappear, but instead will either migrate or become stuck. This stability is an intentional feature of the lens design.
Why Contact Lenses Do Not Dissolve
Contact lenses are constructed from polymers, which are large, stable molecules that resist chemical breakdown in the mild, saline environment of the eye. Soft lenses, which are the most common type, use materials known as hydrogels, such as poly-2-hydroxyethyl methacrylate (HEMA) or silicone hydrogel. These materials form a cross-linked network that absorbs and holds water, making the lens soft and flexible, but they remain chemically inert.
Dissolution requires the breaking of the strong chemical bonds within the polymer structure, a process the body’s tear film cannot accomplish. The tear film is primarily a mild saline solution containing proteins and oils, which lacks the strong acids, bases, or enzymes needed to dismantle the lens material. Even a hydrogel lens containing a high percentage of water maintains its shape because the water is trapped within the fixed polymer lattice. This stability ensures the lens maintains its corrective shape and does not degrade during wear.
Where Lost Lenses Go and How They Change
A misplaced lens must go somewhere, and the eye’s anatomy dictates its possible locations. A popular misconception is that a lens can slip behind the eye, but this is anatomically impossible. The conjunctiva, a thin, transparent membrane, lines the inside of the eyelids and folds back to cover the white part of the eyeball, creating a continuous barrier.
This natural barrier forms a shallow pocket, or cul-de-sac, that prevents any foreign object, including a contact lens, from traveling into the space behind the eyeball. A lens that moves off the cornea will migrate into this cul-de-sac, typically under the upper eyelid, where it can feel uncomfortable or foreign. If a soft lens is left in the eye for an extended period, it may begin to dry out due to a lack of tear film exchange, causing it to stiffen or adhere to the ocular surface. Alternatively, the lens may fold in half or fragment, especially if rubbed, but it remains contained within the front of the eye.
Removing a Stuck Lens and When to Seek Help
Removing a Stuck Lens
The first step in removing a stuck or migrated lens is to thoroughly wash your hands to prevent introducing bacteria to the eye. If the lens is centered and feels stuck, it is likely dehydrated and adhering to the cornea. Applying a few drops of sterile saline solution or rewetting drops will help rehydrate the lens, allowing it to regain its natural flexibility and move freely.
Once lubricated, look in the opposite direction of where you suspect the lens is lodged, such as looking down if it is under the upper lid. Then, gently massage the closed eyelid to help shift the lens back toward the center of the eye. If you cannot locate or dislodge the lens after several gentle attempts, or if you experience persistent symptoms, it is important to seek professional attention.
When to Seek Help
Warning signs that require an immediate visit to an eye care professional include severe, sustained pain, noticeable eye discharge, or blurred vision that continues after the lens has been removed. These symptoms may indicate a corneal abrasion or a potential infection, which needs prompt medical evaluation.