What is a toric?
A toric contact lens is designed to correct astigmatism. With the latest toric designs patients with high amounts of astigmatism can see 20/20 and enjoy comfortable contact lens wear in soft lenses. In the past 5 years, many new toric designs have become available. Many patients who were once told they had to wear a rigid or hard contact lens can now be refit into the new soft toric contact lenses.
How do torics work?
Toric lenses correct vision on the eye in two directions at the same time. Most contact lenses will spin from time to time while they are being worn. A toric should not spin, or it will be correcting vision in the wrong direction. Even a small amount of spin, or rotation, could cause blurred vision with a toric lens. To solve this problem, torics are made thicker at the bottom edge of the lens. Whenever the patient blinks, gravity pulls the thick edge of the toric lens back down. This gives the toric lens the ability to recenter itself whenever it rotates, allowing patients with astigmatism to enjoy clear vision with soft contact lenses.
What is Astigmatism?
Astigmatism is a refractive vision problem. An astigmatic eye has two different prescriptions in different directions at the same time. Astigmatism is not a disease. Instead, the astigmatic eye is often described as being shaped oval instead of round. If the astigmatic eye is oval, then a toric contact lens can be considered an oval contact lens to match the oval shape of the eye.
The diagrams above demonstrate how an eye can have more than one prescription, or power, at the same time. The eye on the top left is spherical because it has the same power in all meridians. The astigmatic eye on the top right has a stronger power (-6.00) in the horizontal meridian than in the vertical meridian (-3.00). The eye on the bottom also has astigmatism, but it is oblique because the rotation is turned 45 degrees from the horizontal.