Toric Lenses for Astigmatism: A Complete Guide

What is Astigmatism?

Astigmatism is a common vision condition that occurs when the cornea (the clear front surface of the eye) or the lens inside the eye has an irregularly curved surface. Instead of being evenly curved like a basketball, an astigmatic eye is shaped more like a football, with one meridian steeper than the other.

This irregular shape prevents light from focusing properly on the retina, resulting in blurred or distorted vision at all distances. Astigmatism often occurs alongside nearsightedness (myopia) or farsightedness (hyperopia).

Causes and Symptoms

Astigmatism is typically present from birth and may be hereditary. It can also develop following an eye injury, disease, or surgery. Common symptoms include:

• Blurred or distorted vision at all distances
• Eyestrain or discomfort
• Headaches, especially after prolonged visual tasks
• Squinting to try to see clearly
• Difficulty driving at night

Diagnosis

Astigmatism is diagnosed during a comprehensive eye examination. Your eye care professional will measure how your eye focuses light using various tests, including a visual acuity test, keratometry (which measures the curvature of your cornea), and refraction.

Introduction to Toric Lenses

Toric lenses are specially designed contact lenses that correct astigmatism. Unlike regular contact lenses, which have a spherical surface, toric lenses have different powers in different meridians of the lens. This design allows them to correct the varying degrees of nearsightedness or farsightedness that occur in different parts of the eye due to astigmatism.

These lenses are weighted at the bottom (called ballasting) or designed with other stabilization features to prevent them from rotating on the eye. This ensures that the corrective power remains aligned with the specific areas of your cornea that need correction.

Types of Toric Lenses

Soft Toric Lenses

Made from the same hydrogel or silicone hydrogel materials as regular soft contacts, these lenses conform to the shape of your eye while maintaining their toric design. They're comfortable and relatively easy to adapt to, making them the most popular choice for correcting astigmatism.

Soft toric lenses are available in various replacement schedules, including daily disposable, bi-weekly, and monthly options. Use our Cost Estimator Tool to compare the costs of different replacement schedules.

Rigid Gas Permeable (RGP) Toric Lenses

RGP toric lenses provide exceptionally clear vision, especially for people with more significant astigmatism. They maintain their shape rather than conforming to the irregularity of the cornea, which can result in sharper vision. However, they typically require a longer adaptation period and may not be as comfortable initially as soft lenses.

Hybrid Toric Lenses

These lenses combine a rigid center with a soft outer skirt, aiming to provide both the visual clarity of RGP lenses and the comfort of soft lenses. They're an excellent option for people who need the superior optics of rigid lenses but struggle with their comfort.

How Toric Lenses Work

Toric lenses have a few key design features that make them effective for correcting astigmatism:

Different Powers in Different Meridians

Unlike regular contact lenses, which have the same power throughout, toric lenses have different powers in different parts of the lens. This allows them to correct the varying degrees of refractive error across different meridians of your eye.

Stabilization Features

To ensure the lens maintains the correct orientation on your eye, toric lenses incorporate stabilization features such as:

• Prism ballast: The bottom of the lens is slightly thicker, using gravity to keep the lens oriented properly.
• Thin zones: Thin areas at the top and bottom of the lens that interact with the eyelids to maintain orientation.
• Peri-ballast: A design that thins the lens in specific areas to create a more stable fit.

Orientation Markings

Toric lenses often have tiny markings that allow your eye care professional to check if the lens is sitting in the correct position on your eye. These markings are usually at the 6 o'clock position when the lens is properly oriented.

Fitting Toric Lenses

Fitting toric lenses is more complex than fitting regular contact lenses and requires specialized expertise. The process typically involves:

• A comprehensive eye exam to determine your exact prescription, including the axis of astigmatism
• Selection of an appropriate lens design and material based on your specific needs
• Trial fitting to assess how well the lens centers and stabilizes on your eye
• Vision testing to ensure the lenses provide clear, stable vision
• Follow-up appointments to evaluate comfort and vision over time

Because of the precision required, expect the fitting process to take longer and potentially require more follow-up visits than with regular contact lenses.

Advantages and Disadvantages

Advantages of Toric Lenses

• Provide clear vision for people with astigmatism who prefer contacts over glasses
• Available in a wide range of prescriptions to correct various degrees of astigmatism
• Offer freedom from glasses for sports and other activities
• Available in different replacement schedules to suit various lifestyles and budgets
• Can provide more natural vision than glasses for some people with astigmatism

Disadvantages of Toric Lenses

• More expensive than regular contact lenses
• May rotate on the eye, temporarily blurring vision until they reorient
• Fitting process is more complex and may require more follow-up visits
• Limited availability in some specialty materials or designs
• May not fully correct very high levels of astigmatism

Care and Maintenance

Proper care of toric lenses is similar to that of regular contact lenses but even more important due to their specialized design and higher cost. Follow these essential guidelines:

• Wash and dry your hands thoroughly before handling lenses
• Clean and disinfect lenses according to your eye care professional's recommendations
• Never use tap water or saliva to clean or moisten lenses
• Replace lenses according to the recommended schedule
• Store lenses in fresh solution in a clean case
• Replace your lens case every three months

For more detailed information on proper lens care, see our guide to contact lens care and cleaning.

Frequently Asked Questions

Conclusion

Toric contact lenses have revolutionized vision correction for people with astigmatism, offering an effective alternative to glasses. While they require more specialized fitting and are more expensive than regular contact lenses, the clear vision and freedom they provide make them worth considering.

As with any contact lenses, success with toric lenses depends on proper fitting, good hygiene, and following the recommended replacement schedule. Regular check-ups with your eye care professional will ensure your lenses continue to provide optimal vision and comfort.

Remember to check out our guide on when to replace your contact lensesand our tips for preventing dry eyes with contactsto maintain optimal eye health and comfort with your toric lenses.