Daily contact lenses are available for astigmatism and are called daily disposable toric lenses. Astigmatism is a common vision condition caused by an irregularly shaped cornea or lens inside the eye. This imperfection causes light rays to focus on multiple points instead of a single point on the retina, resulting in blurred or distorted vision at all distances. Contact lenses designed to correct this refractive error have a unique optical geometry to counteract the asymmetrical curvature of the eye.
Understanding Daily Toric Contact Lenses
Daily toric contact lenses are widely available and represent a significant advancement in vision correction for people with astigmatism. Unlike a standard contact lens, which has a uniform spherical power, a toric lens features different corrective powers in different meridians. This design allows the lens to precisely match and neutralize the uneven shape of the astigmatic eye, bringing light into a single, sharp focus on the retina.
The primary advantage of the daily disposable format lies in convenience and hygiene. Daily lenses are worn once and discarded, eliminating the need for cleaning solutions, storage cases, and disinfecting routines. This single-use schedule significantly reduces deposit buildup and eye infections, making them an excellent choice for individuals with allergies or those prone to dry eyes.
While reusable toric lenses are available, the daily disposable option offers a fresh, clean lens every morning, translating to superior comfort, especially for new wearers. This replacement schedule is beneficial for part-time wearers, travelers, or those who participate in sports, offering maximum flexibility without compromising prescription precision. The availability of daily toric lenses has made contact lens wear a viable and comfortable option for a broader range of people with astigmatism.
How Toric Lenses Correct Astigmatism
Toric lenses are designed with a specific optical geometry that incorporates two features: cylinder power and axis. The cylinder power quantifies the amount of astigmatism needing correction, while the axis specifies the orientation of that correction, measured in degrees. Because the corrective power is not uniform across the lens, it is necessary for the lens to maintain a stable alignment on the eye.
Manufacturers employ engineering techniques to ensure rotational stability, preventing the lens from shifting with blinks or eye movements. One common stabilization method is prism ballast, where a section of the lens, typically the bottom edge, is made slightly thicker or heavier. This weighted base interacts with the lower eyelid and leverages gravity to guide the lens back into the correct position after a blink.
Another stabilization design involves creating thin zones or dynamic stabilization areas on the lens periphery. These regions interact with the pressure applied by the eyelids during a blink, actively guiding the lens to its optimal alignment. The success of the toric lens depends on this stability, as even a small degree of rotation can cause the vision to become momentarily blurry or distorted.
The Process of Fitting and Obtaining Daily Toric Lenses
Obtaining daily toric lenses begins with a comprehensive eye examination that includes specialized measurements. The eye care professional uses instruments like a keratometer or corneal topographer to map the surface of the cornea. Corneal topography generates a detailed, color-coded map showing the curvature and elevation, which is essential for determining the correct lens parameters for an irregular shape.
Based on the measurements of the cylinder and axis, a trial lens is selected for the patient. The fitting process requires the patient to wear the trial lens for a period, often around ten minutes, allowing the stabilization features to settle. The practitioner then evaluates the lens’s movement, centration, and rotational stability, often using subtle laser etchings on the periphery to assess its alignment.
If the lens rotates slightly off-axis, the doctor may compensate by adjusting the prescribed axis using methods like the LARS (Left Add, Right Subtract) rule before ordering the final prescription. Follow-up visits are routine to ensure the lens continues to provide clear, stable vision and comfortable wear. While daily toric lenses generally cost more than monthly options—ranging approximately from $500 to over $1,000 per eye yearly—the added convenience and hygiene of a fresh lens daily often justify the investment for many wearers.