Toric Contact Lenses
What Are Toric Lenses?
Toric contact lenses correct astigmatism They can be made from HEMA (soft), silicone hydrogel, or gas permeable materials.
Unlike spherical lenses, toric lenses have two different powers in the lens. This characteristic means that the toric lens must remain in one position for the best visual acuity. Too much movement of the lens can significantly reduce visibility. Some of them are made heavier at the bottom to prevent them from rotating or moving too much.
Who Are Toric Lenses For?
Toric lenses can be worn by anyone with corneal astigmatism, lenticular astigmatism, or combinations of both. People with astigmatism who have tried spherical lenses, but continue to have unsatisfactory vision are candidates for toric lenses. The specific material, style or type of contact lens used depends upon the needs, vision quality, and type of astigmatism. Based upon your individual characteristics, your eye doctor will discuss which options will best serve your needs.
Toric Lens Costs
Everything involved with toric lenses—fittings, exams, and the lenses themselves—is more expensive than regular lenses. Toric lenses are also more expensive than ordinary contacts depending on your health coverage and the complexity of your case.
Daily Care and Usage
The proper way to care for your lenses depends on which type of toric lens you wear. Daily disposable torics are said to be the most convenient when it comes to caring for your contacts. They do not require any extra care products like solutions and cases. Those who wear extended-wear lenses should properly clean and disinfect their lenses daily and try not to expose themselves to too much smoke, chemicals, etc. Overnight wearers do not necessarily need to clean or disinfect their lenses daily, but nothing is wrong with this practice. Regardless of whether your lenses have been customized for color or multifocal functions, your doctor should have specific care instructions for you to take home. Usually you soak your lenses in a solution made for cleaning and disinfecting, followed by a rinse.
Toric Lens Materials
Toric lenses can be made of any of the following materials; Silicone Hydrogel (the most common), Omafilcon A, Methafilcon A, Polymacon, Hilafilcon A, or Hilafilcon B.
Customized Options for Toric Lenses
More than 40 percent of the vision-corrected population requires astigmatic corrections for levels of 0.75D or more. This is one of the many reasons why scientists have developed toric lens with multiple options like disposability, color, and multifocal capabilities. Disposable toric contact lenses can be either daily disposables or thirty-day silicone hydrogel wear, and are available in many colors to change or enhance your natural eye color. Some colors are available as disposables, but most colored toric lenses are non-disposable. Multifocals are also non-disposable, but they are great for correcting presbyopia. Some brands have developed soft toric multifocal lenses, but doctors often prescribe an RGP lens for correcting presbyopia.
Types of Toric Lenses
Toric lenses can be made from either soft or rigid gas-permeable materials. Each comes in a variety of designs and different materials. Rigid gas-permeable lenses are made of stiff material that retains its shape when you blink and comes in numerous bifocal and multifocal designs like back toric (bitoric), front toric, and bitoric lenses with prism ballast. RGP lenses are made of permeable materials that allow oxygen to reach the eye easily. They are durable lenses, but they can still break or tear. They incorporate silicone for flexibility, but require the wearer to adapt to the shape and texture of the lens before they become comfortable.
Problems with Toric Lenses
Unfortunately, some patients will reject toric lenses. Discomfort is the main reason patients stop using toric lenses. This discomfort can be caused by movement of the lens or by constant awareness of the lens due to the pressure it exerts on the lower lid. Another problem some patients have is the constant movement of the axis in the lens. The axis is in the middle of the lens, and it keeps your line of vision clear. If the axis is constantly moving, a degradation of vision will occur. Improper fitting of the lens can also be a nuisance.
Patients sometimes report vision problems like blurriness and fuzziness after a few hours of wearing RGP lenses. Some also experience excessive dryness of the eye after only a few hours of wear. Fogginess due to edema (swelling) is usually a bigger problem for patients who suffer from photophobia, or light sensitivity.
Options for Mild Astigmatism
If you have mild astigmatism, between zero and 1.00D, a toric lens may not even be necessary. If your doctor approves, you may be able to wear a regular spherical RGP or even a spherical soft lens instead. RGPs can cover up the need for a correction of astigmatism and doctors can give you a higher-powered spherical soft lens to mask a small astigmatic correction.
Talking to Your Eye Doctor
Here are some questions to ask your eye-care provider about toric lenses:
- Why do you think toric lenses are the best option for me?
- What contact lens type, style, or design would benefit me most?
- What is the cost of this type of lens?
- Do I have any other options?
- How much do the different types of lenses cost?
- How many visits will it take before we find the right contact lens for me?
- Which cleaning solution system do I need to use?
- Contact Lens Headlines, May 2011, Hybrid Contacts Superior to Toric Soft Lenses for Astigmatism, Say 9 of 10 Prescribers http://www.contactlensheadlines.com/6739/eye-docs-rate-hybrids-superior/
- M. Beers, MD “Merck Manual of Medical Information” 2nd Home Edition (Pocket Books, 2003) 1287