Astigmatism is a condition that causes blurred vision (in some cases double vision) because rather than being round, the front of the eye (the cornea) has two curves instead of one, therefore, having two focal points instead of one. Many doctors may refer to astigmatism as having a football shaped front surface of the eye, more accurately, an astigmatic cornea is closely shaped like a Rugby ball. This makes it hard for traditional spherical (round) contact lenses to fit and therefore requires specialized contact lenses such as toric lenses or rigid gas permeable lenses (RGPs).
Toric contact lenses are designed to correct astigmatism and custom made to fit the eye of the patient. Most are made of soft material designed to stay in place on the eye, however in some cases, when the rotation of the lens (due to blinking and eye movement) can’t be stopped, gas permeable lenses might be tried. Due to the customization and more complicated fitting process required for these lenses, they are more expensive and take more time for the contact lens laboratory to make than traditional lenses.
What are Toric Contact Lenses?
Rather than having a perfectly spherical surface like standard contact lenses, toric lenses have a more oblong shape made to accommodate the shape of the astigmatic eye. Toric lenses can be made of either soft or rigid gas permeable (RGP or GP) lens material, however the soft toric lenses are more common.
Toric contact lenses are also designed in such a way that the lenses stay in place on the eye to maintain proper vision. This is commonly refered to as a ballast lens; ballast lenses can be either back surfaced prism-ballast, front surface ballasted or cast-molded Lo-Torque designed, Sometimes as the eye moves or blinks the lens can rotate considerably on the eye. If this rotation continues with a soft toric lens, a rigid gas permeable lens might be more effective. Rigid gas permeable lenses have a longer initial adjustment time, but once this has passed they are usually just as comfortable as soft contact lenses and they are often easier to care for.
Toric lenses are available in every wearing schedule from daily disposable to long-term wear. In some cases you may even find colored toric contact lenses. Due to the customization required, toric lenses tend to be more expensive and may take more laboratory time to make than traditional lenses.
If you have astigmatism, finding the right fit for your contact lenses is essential. Speak to your eye care team today for a full assessment to determine which type of toric lenses will work best for you to help you see and feel your best.