Contact lenses are an effective way to correct vision problems, including nearsightedness and farsightedness. For individuals with astigmatism, which results from an irregularly shaped cornea or lens, a specialized product called a toric contact lens is necessary. Unlike standard spherical lenses, toric lenses are designed with a specific axis of correction and must maintain a particular orientation on the eye to provide clear vision. This requirement for precise alignment makes the insertion process for toric lenses a careful procedure, ensuring the lens settles correctly to correct the vision error.
Understanding Toric Lens Orientation
Toric lenses differ from traditional contact lenses because they possess two different power curves integrated into the design. This construction is necessary to counteract the two different curvatures found on an astigmatic eye. To ensure the corrective power remains in the correct position, manufacturers incorporate stabilization features into the lens structure.
One common stabilization method is prism ballast, where a section of the lens is made slightly thicker or heavier, causing it to settle consistently at the bottom of the eye due to gravity and interaction with the eyelids. Other designs use thin zones, where the edges are tapered to interact with the blink, guiding the lens back to its intended position. These stabilization methods ensure the lens’s corrective axis aligns with the eye’s required axis. Many toric lenses feature subtle orientation markings, such as small dots, lines, or etchings, which indicate the stabilization axis to the wearer and the eye care professional.
Essential Preparation Before Handling
Before handling any contact lens, it is necessary to establish a clean and controlled environment to prevent eye infection or irritation. Begin by washing hands thoroughly with a mild, non-cosmetic soap, avoiding oil-based or strongly scented varieties. Dry hands completely using a lint-free towel, as residual moisture or fibers can transfer to the lens surface and cause discomfort.
The lens requires a visual inspection before it is placed on the eye. Check the lens for any minute tears, nicks, or debris. It is also necessary to confirm the lens is not inside out. A properly oriented lens will resemble a smooth, uniform bowl shape when resting on the fingertip, while an inverted lens will have a noticeable flare or rim around the edge.
The Step-by-Step Insertion Technique
To begin the insertion process, place the ready lens on the tip of the index finger of your dominant hand, ensuring the concave side is facing up. Before lifting the lens to the eye, it can be helpful to briefly observe the orientation markings, if visible, and attempt to align them close to the 6 o’clock position on the finger. This initial placement can help reduce the time required for the lens to settle once it is on the eye.
Use the middle finger of the lens-holding hand to pull down the lower eyelid, exposing the lower white of the eye. With the non-dominant hand, hold the upper eyelid near the lash line and pull it gently upward, preventing a blink. Keeping both eyelids wide open is important to maintain stability and ensure the lens does not fold upon contact with the eye.
Carefully bring the fingertip holding the lens toward the eye, looking straight ahead or slightly upward, and gently place the lens directly onto the cornea or the lower sclera (the white of the eye). The lens should transfer smoothly from the finger to the eye surface. Once the lens is in contact with the eye, slowly release the lower eyelid first, then the upper eyelid.
Verifying Proper Alignment and Comfort
Immediately after the lens is on the eye, it is normal for vision to be slightly blurry until the lens stabilizes. The ballast design of the toric lens will cause it to rotate into the intended position, which typically occurs within the first few blinks. Allow the lens approximately 10 to 30 seconds to settle and align itself naturally with the astigmatism axis before attempting any adjustments.
Once the initial settling time has passed, assess the clarity of vision; if the lens is correctly aligned, vision should be sharp. If vision remains blurred or noticeably distorted, it may indicate that the lens has rotated incorrectly and is not aligning the corrective axis properly.
In this case, one can attempt a minor adjustment by looking in the opposite direction of the misalignment and gently nudging the edge of the lens on the white of the eye with a clean, dry fingertip to encourage rotation. If vision is still poor after a gentle rotation attempt, the lens should be removed, rinsed with fresh solution, and reinserted, as severe blurriness may indicate a significant initial misalignment or a lens that is inside out.