Astigmatism is a condition that is caused by an irregular shape of the cornea – the clear part of the front of eye that covers the iris and the pupil. The cornea is usually smooth, round, and spherical but in an astigmatic eye, the cornea is more oval and elliptical in shape and develops a second curve. One of the primary duties of the cornea is to focus light onto the retina which enables you to see clearly. When the cornea is not spherically shaped and develops two curves, this creates two focal points therefore causing blurred vision.
The irregular shape of the eye makes it hard for traditional ‘spherical’ contact lenses to fit and provide clear vision and therefore requires specialized contact lenses such as toric lenses or rigid gas permeable lenses (RGPs).
What are Toric Contact Lenses?
Toric contact lenses are designed to correct astigmatism and custom made to fit the eye of the patient. Rather than having a perfectly spherical surface like standard contact lenses, toric lenses have a specific design 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 optimum vision. 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 provide clear, sharp vision.
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 slightly more expensive and if custom-made 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 optometrist today for a full assessment to determine which type of toric lenses will work to help you see well and feel great.