Contact lenses are thin, flexible materials used to correct vision. A common mistake is accidentally inserting a lens that is incorrectly oriented. An inside-out lens means the smooth, concave surface designed to align with the cornea is inverted, causing the edges to subtly flare outward. This error leads to immediate and noticeable issues upon placement. Understanding this frequent mistake and the corrective steps is essential for routine contact lens care.
Visual Cues for Identification
Wearers can confirm the lens orientation before insertion using simple methods. The most recognized technique is the “Taco Test.” By gently grasping the lens between the thumb and forefinger and folding it slightly, a properly oriented lens will form a smooth, upward curve resembling a hard-shell taco. If the lens is inverted, the edges will resist this smooth fold and flare outward.
Another visual inspection involves placing the lens on the tip of an index finger and observing its profile from the side. A lens in the correct position will look like a perfect cup or half-ball, with a continuous, smooth curve. If the lens is inside-out, the edges will turn outward, resembling a rimmed soup bowl. Some manufacturers also include tiny, laser-etched markings near the edge of the lens. If these markings are readable and not mirrored, the lens is correctly oriented for insertion.
Immediate Physical Sensation
The moment an inverted lens is placed on the eye, the wearer experiences immediate discomfort. This feeling is often described as grittiness or a foreign object trapped in the eye. The flared edges of the inverted lens do not conform smoothly to the corneal surface, causing constant mechanical irritation against the conjunctiva and surrounding tissues. This continuous rubbing triggers excessive tearing and watering as the eye attempts to flush out the irritant.
The lens may also feel unstable or prone to movement, slipping noticeably when the wearer blinks or shifts their gaze. A misaligned lens shifts out of place easily or may even pop out unexpectedly because it does not create the necessary suction with the cornea. While vision might be slightly blurry due to the poor fit, the primary symptom is persistent irritation that signals a need for immediate correction.
Potential Risks and Corrective Steps
While wearing a lens inside-out is not an ocular emergency, allowing it to remain on the eye for an extended period increases the risk of damaging the ocular surface. The continuous friction from the non-conforming edge can lead to irritation, redness, and localized inflammation. This constant mechanical stress can potentially cause microscopic corneal abrasions, which are tiny scratches on the outermost layer of the cornea. These abrasions, although usually minor, compromise the eye’s natural defenses and increase susceptibility to infection if the lens is contaminated.
The immediate corrective step is to remove the lens after washing hands with soap and water to minimize bacterial transfer. After removal, the lens should be inspected and rinsed with fresh contact lens solution, avoiding tap water. The wearer must then re-check the orientation using the established visual cues, ensuring the lens forms a smooth cup shape before re-insertion. If discomfort, blurring, or redness persists for more than an hour after correction, discontinue lens use for the day. Persistent pain, continued blurring, or sensitivity to light require a professional examination to rule out potential corneal damage.