Soft contact lenses are made from thin, flexible materials, allowing them to easily invert while handling. Ensuring the correct orientation before insertion significantly impacts both eye comfort and visual clarity. A correctly positioned lens sits smoothly on the cornea, while an inside-out lens will not match the eye’s curvature, leading to immediate issues. Learning how to check the lens’s shape prevents discomfort and maintains proper eye health.
The Visual Bowl Test
The primary method for determining a lens’s orientation involves visually inspecting its overall shape while it rests on your fingertip. Place the lens on the pad of your index finger with the edges pointing upward, then hold your finger up to a light source at eye level.
A correctly oriented lens forms a smooth, deep, rounded bowl, sometimes described as resembling a “taco” shell. The edges curve inward toward each other without flaring out, and the surface appears continuous and symmetrical.
An inverted, or inside-out, lens shows a distinctly different profile when viewed from the side. The edges visibly flare outward, giving the lens a shallower, wider appearance, similar to a saucer. This outward turn indicates the lens’s curvature is reversed and must be gently flipped before insertion.
Checking the Edges
A secondary check involves closely inspecting the lens’s outermost rim to confirm the orientation. When correctly positioned, the edge appears smooth, continuous, and rounded, following the natural curve of the bowl. This smooth profile minimizes friction against the eyelid and cornea.
If the lens is inside out, the edge shows a slight, noticeable ridge or lip where the material turns outward. This flared edge profile is why an inverted lens causes discomfort upon blinking. Some manufacturers include tiny laser-etched markings, such as the numbers “123,” near the edge to aid in this check. If these markings read correctly from left to right, the lens is properly oriented; if they appear reversed, the lens is inside out.
What Happens If You Wear an Inside-Out Lens
Inserting an incorrectly oriented lens results in immediate and persistent discomfort. This irritation occurs because the flared edge constantly rubs against the sensitive tissues of the eye and inner eyelid. The inverted curvature does not match the cornea’s natural dome shape, preventing the lens from seating securely.
This poor fit causes the lens to move around excessively, often feeling like it is floating or shifting with every blink. Vision may also be unstable, blurry, or distorted because the lens is not centered correctly over the pupil. While wearing an inside-out lens is uncomfortable, it does not cause permanent damage to the eye. The lens should be removed immediately, cleaned with contact solution, and reinserted after confirming the correct orientation.