Toric contact lenses are often prescribed to people who have astigmatism, a condition that is diagnosed and tested through a comprehensive optometric exam. Although prescription glasses can be used effectively, toric lenses are preferred by people for the convenience and vision correction they provide.
What Is Astigmatism?
Astigmatism is a condition that affects vision, causing blurry images. The problem begins in the cornea, the frontal part of the eye covering the iris. The cornea, along with the lens and the anterior chamber, is responsible for refracting light that enters the eye. In a person with astigmatism, there may be a problem in the lens curvature of the eye or in the shape of the cornea. When light enters the eye of an astigmatic person, the eye fails to focus properly, causing the appearance of blurry images regardless of their distance from the viewer.
Astigmatism is fairly common in people with nearsightedness (myopia) and farsightedness (hyperopia). Like these conditions, astigmatism is also known as a refractive error. It usually runs in families and may be present in an individual from birth. It may also improve or worsen over time.
How Can Toric Contact Lenses Help Astigmatism?
A toric lens is basically a contact lens but is shaped like a sliced side of a doughnut. The doughnut shape is called a torus, hence the name. The shape is deliberate because it produces a refractive power that is different from the power that regular lenses produce. Another key difference between toric and regular lenses is the prescription. While a regular lens has a single prescription, a toric lens may have varying powers. The lens contains different prescription grades at different meridians, allowing the eye to focus better. Since lenses tend to move on the surface of the eye, toric lenses have a slightly weighted bottom to keep them in place and ensure that the different prescriptions are at the proper orientation.
Who Can Wear Toric Lenses?
Toric lenses are designed to be worn by people who have astigmatism. They have to be diagnosed with the condition first by a licensed eye specialist such as an optometrist or an opthalmologist. It is important that fitting the lenses is supervised by an eye doctor. Toric contact lenses carry a specific orientation and they have to be fitted perfectly to ensure visual clarity. Toric lenses are available as daily wear/disposable, and may soft, hard, or rigid gas permeable. People who choose rigid or hard lenses may need time to adjust to the texture but these lenses tend to stay in place. Soft lenses, however, are easier to put on and feel more comfortable. They may require more care during fitting so they do not move too much on the surface of the eye.