CooperVision’s Optimized Toric Lens Geometry™

To create the necessary stability with certain contact lenses for astigmatism, CooperVision has engineered a design referred to as “Optimized Toric Lens Geometry”. This contact lens design is utilized in the following lenses:

• Biofinity Toric
• MyDay Toric
• Avaira Vitality Toric 

A major portion of stabilizing lenses with Optimized Toric Lens Geometry is the “prism ballast” zone located in the inferior portion of the lens. This zone makes the lens thicker inferiorly, and utilizes gravity, along with other aspects of the lens, to hold the lens in place.

CooperVision attributes each of these components of the Optimized Toric Lens Geometry design to making it comfortable, clear, and stable:

• 1- Uniform horizontal ISO thickness
• 2- Wide ballast band
• 3- Smooth, continuous surface
• 4- Larger toric optic zone
• 5- Unique back surface curvature

What makes a toric contact lens (a lens for Astigmatism) different from other lenses?

With astigmatism, there are two points of focus that need to be corrected in the back of the eye. Both of these points need to be shifted onto the fovea for our best corrected vision. In glasses, we move these points aligning the correct prescription in these necessary directions, and lock  the lenses into position with the frame. With contact lenses, we need to accomplish the same thing, but we do not have a frame to hold the prescriptions in the precise meridian. Instead, we have to rely upon the mechanics of the contact lens to hold the prescriptions into place. A contact lens has nothing to hold on to.  A well fit and stable (one that does not rotate these prescriptions away from their correct alignment) lens will create clear and stable vision, while an unstable lens will result in often blurry and unstable vision.

Illustration Example of Astigmatism Correction: With astigmatism, light focuses at two points instead of one. For clear vision, all light needs to focus on the fovea. In this image of an eye with astigmatism, one point is 3.00 diopters away from the fovea, the other is 4.25 diopters away from the fovea. Since the points need to be moved backward to the fovea, this is considered a minus (-) direction. When the Rx is written, the first number written represents the SPHERE POWER, the second number written is the amount of astigmatism (the width of the gap) represented as the CYLINDER POWER. The final number is the meridian of the sphere power, also known as the AXIS of the cylinder power.