The question of how far a contact lens can travel in the eye often stems from the fear that it might slip behind the eyeball and become permanently lost. This common concern is based on a misunderstanding of ocular anatomy. The structure of the eye makes it physically impossible for a lens to roll completely behind the eyeball. Instead, a misplaced contact lens is contained to a small, accessible area at the front of the eye, which limits its movement considerably.
The Eye’s Natural Barrier
The eye is not an open socket where objects can pass through to the back of the head. A thin, transparent membrane called the conjunctiva acts as a barrier to prevent migration. This tissue lines the inner surfaces of the upper and lower eyelids and folds back to cover the white part of the eye, known as the sclera.
This continuous folding forms a protective pocket, or cul-de-sac, known as the conjunctival sac. The sac seals off the area at the back of the eye, stopping any foreign object, including a contact lens, from moving beyond the front surface. Therefore, the lens can only move within the space between the eyelid and the eyeball.
Common Locations for Displaced Lenses
When a contact lens feels “lost,” it has moved off the cornea and into one of the recesses of the conjunctival sac. The deepest area of this space is typically located high up under the upper eyelid, making this the most frequent resting spot for a displaced lens. The lens may also be found folded over itself or tucked into the crease of the lower inner eyelid.
Several factors can cause a lens to dislodge from the cornea. Excessive eye rubbing can easily push the lens off-center. A lack of sufficient moisture, such as from dry eyes, can also cause the lens to adhere or fold over, leading it to migrate under the lid during a blink.
Retrieving a Lost Contact and Safety Guidelines
The first step in retrieving a displaced lens is to wash your hands with soap and water to prevent introducing bacteria to the eye. Next, instill a few drops of sterile saline solution or rewetting drops into the eye to lubricate the lens and encourage it to move. This rehydration is important if the lens feels stuck due to dryness.
Once the eye is lubricated, look in the opposite direction of where you suspect the lens is located; for example, if the lens is under the upper lid, look down. With your eye closed, gently massage your eyelid toward the center of your eye. This can coax the lens back into a visible position. If the lens is visible, carefully slide it back over the cornea where it can be removed in the usual manner.
If you are dealing with a rigid gas-permeable (RGP) lens, avoid massaging your eyelid, as the harder material could scratch the cornea. Instead, use the flat part of your fingertip to gently press the eye near the edge of the stuck lens to break the suction holding it in place.
If the eye becomes painful, red, or if your vision is affected, or if you are unable to retrieve the lens after a few gentle attempts, stop immediately. Seeking professional assistance from an eye care specialist is the safest course of action to ensure the lens is removed without causing damage to the eye’s surface.