Yes, you can obtain colored contact lenses designed to correct astigmatism, but they are a specialized product requiring precise engineering. Astigmatism is a common vision condition where the cornea or the lens inside the eye is curved imperfectly, shaped more like a football than a basketball. This irregular curvature causes light to focus on multiple points instead of a single point on the retina, resulting in blurred or distorted vision. Correcting this issue while integrating a cosmetic color requires combining advanced optics with aesthetic design.
How Lenses Correct Astigmatism
Correcting astigmatism requires a specialized design known as a toric lens, which differs significantly from a standard spherical contact lens. Toric lenses feature different refractive powers in their horizontal and vertical orientations, allowing them to counteract the irregular shape of the astigmatic eye. This design incorporates two measurements on the prescription: a sphere power to correct general vision issues and a cylinder power with a specific axis to address the degree and orientation of the astigmatism.
For the lens to work, it must maintain a precise orientation on the eye, aligning the corrective power exactly with the eye’s irregular curvature. Manufacturers achieve this rotational stability through various stabilization techniques. These designs often involve thicker or thinner zones, such as prism ballast or dual-thin zones, which interact with the eyelids during blinking to prevent rotation.
If the toric lens rotates even slightly, the corrective cylinder power shifts out of alignment, immediately causing vision to become blurry or unstable. This need for constant, stable alignment makes the manufacturing and fitting of toric lenses complex. The engineering ensures the lens returns quickly to its correct resting position after every blink, guaranteeing consistent visual clarity.
Applying Cosmetic Color to Specialized Lenses
Integrating a cosmetic color into a toric lens design presents a unique manufacturing challenge because the color must not interfere with stabilization or optical performance. The color pattern must be precisely aligned relative to the stabilized design so the colored portion remains centered over the iris. The aesthetic effect must be stable and consistent, matching the vision correction.
Two types of cosmetic tints are available and can be integrated into toric designs. Enhancement tints are translucent and intensify the natural eye color, suitable for people with lighter eyes. Opaque tints use solid patterns to completely change the eye’s appearance, which is necessary for a noticeable color change on darker eyes.
Toric lenses require many power combinations, varying in sphere, cylinder, and axis. Combining these with multiple color options greatly increases manufacturing complexity and cost. Consequently, the selection of colored toric lenses is often limited in available colors and prescription ranges compared to non-tinted toric lenses. People with high degrees of astigmatism or multi-focal needs may find their choices restricted or require custom-made products.
Why Professional Fitting is Essential
All contact lenses are classified as medical devices and require a valid prescription from an eye care professional. This requirement is even more important for toric lenses due to the sensitivity of their design. A professional fitting is mandatory to ensure the lens parameters perfectly match the unique needs of the eye.
The eye doctor must take several precise measurements, including the curvature of the cornea, known as the base curve, and the diameter of the eye. For toric lenses, the fitting process involves assessing the lens’s rotational stability. The practitioner observes how the lens settles and interacts with the eyelids during blinking to confirm the corrective axis remains correctly aligned.
Improperly fitted lenses or incorrect axis alignment can lead to fluctuating vision, discomfort, and irritation. More serious health risks, such as corneal abrasions, eye infections, or reduced oxygen to the cornea (hypoxia), can occur if the lens is too tight or too loose. A professional fitting ensures optimal visual performance and protects the long-term health of the eyes.