Astigmatism is a common visual condition where the front surface of the eye, the cornea or the lens, is irregularly curved, shaped more like a football than a perfect sphere. This asymmetrical shape causes light to focus unevenly on the retina, resulting in blurred or distorted vision at any distance. The good news for those seeking both clear vision and a cosmetic change is that specialized colored contact lenses for astigmatism, known as toric colored lenses, are available. These lenses combine the precise vision correction required for an irregular eye shape with the aesthetic appeal of an altered eye color.
How Toric Lenses Correct Astigmatism
Toric lenses differ significantly from standard spherical contacts, which only correct nearsightedness or farsightedness with a uniform power across the lens. Astigmatism correction requires the lens to have different optical powers in different meridians to neutralize the eye’s uneven curvature. This difference in power is quantified by two specific measurements on a prescription: cylinder power and the axis, which indicates the orientation of the astigmatism in degrees around the eye.
The effectiveness of a toric lens depends entirely on its ability to maintain a stable, non-rotating position on the eye, ensuring the corrective powers align perfectly with the eye’s unique axis. Manufacturers employ sophisticated mechanisms to achieve this rotational stability, counteracting the natural movement of the eye and the pressure from blinking.
One common method is prism ballast, which involves incorporating a slightly thicker or weighted zone, often toward the bottom of the lens, to leverage gravity and eyelid interaction. Another stabilization technique uses thin and thick zones strategically positioned on the lens surface. These features interact with the eyelids during a blink to guide the lens back into its correct alignment. This precise engineering ensures the lens’s corrective cylinder power remains consistently aligned with the astigmatism axis for stable, crisp vision throughout the day.
Customization and Availability of Colored Toric Contacts
The specialized nature of toric lenses, compounded by the addition of color pigment, means that the market for colored toric contacts is less expansive than for standard contacts. Consumers typically encounter two main categories: mass-produced “stock” lenses and fully customized lenses.
Stock Lenses
Stock colored toric lenses offer a limited range of cylinder powers, axes, and color options, making them suitable only for those whose prescriptions fall within a specific, narrower range.
Custom Lenses
For individuals with higher levels of astigmatism or a less common axis, a fully customized lens is often the only option. These specialized lenses provide a much wider spectrum of prescription parameters and color choices, including both enhancement tints and opaque colors for a complete eye color change. However, the personalized manufacturing process for custom toric lenses is complex and can result in significantly longer waiting times, often taking between eight and twelve weeks for production. The increased complexity and lower volume of production also contribute to a notably higher cost compared to stock or clear toric lenses.
The Specialized Fitting Process
Obtaining colored toric contacts requires a specialized fitting process performed by an eye care professional, going far beyond a simple routine eye exam. The fitting begins with precise measurements of the eye’s surface, including the specific axis of astigmatism, often using detailed instruments like a corneal topographer. The doctor then selects a trial lens based on these measurements, which is worn by the patient for a short period to assess its performance.
The most important step is monitoring the lens’s rotational stability on the eye, as the lens must settle into the correct position after every blink. Eye care professionals use subtle scribe marks or etchings located on the lens periphery to objectively measure any degree of rotation. If the lens rotates off-axis, the doctor may use a calculation method, often referred to as LARS (Left Add, Right Subtract), to adjust the final prescription axis to compensate for the lens movement. This meticulous process ensures that the corrective power aligns accurately for clear vision and that the color portion of the lens remains correctly centered over the iris.
Essential Safety and Care Guidelines
Wearing any contact lens requires strict adherence to hygiene, and this is particularly true for the more complex colored toric lenses.
- Always start by washing your hands thoroughly with non-cosmetic soap and drying them with a lint-free towel before handling your lenses.
- It is crucial to use only the specific contact lens solution recommended by your eye care professional for cleaning and storing the lenses.
- Never use tap water or saliva, as these introduce microorganisms that can lead to serious eye infections.
The composite nature of colored toric lenses, which combine the thickness required for astigmatism correction with the embedded color pigment, can sometimes result in a slightly reduced oxygen permeability compared to clear lenses. To maintain eye health, it is important to follow the recommended wearing schedule and replacement frequency precisely, whether daily, bi-weekly, or monthly. Unless your specific lenses are explicitly approved by your doctor for extended wear, you should avoid sleeping in them to minimize the risk of corneal complications.