Different types of astigmatism: what is yours?
Astigmatism refers to the condition in which irregularity in the shape of the corneas causes refractive error and blurred vision. The irregular shape of corneas results in the refraction of light onto multiple points in the eye, rather than focusing it into a single point, thus blurring vision. So how can you correct astigmatism?
Can you wear contacts with astigmatism despite their irregular shape? To correct astigmatism, light must be refracted into the eye from a specific direction. Regular soft lenses, which make up the bulk of the contact lenses on the market today, tend to shift and swirl on the surface of your eyes each time you blink.
So, to correct astigmatism, regular soft lenses just won’t do, since they are not able to account for the irregular shape of the corneas and retain their position to refract light in a specific direction.
To address this problem, a specific kind of soft contact lens was developed: toric contact lenses for astigmatism. These lenses were designed to account for the shape of the corneas while maintaining their position and orientation on the corneas, so that light is refracted onto the retinas only from a specific direction.
Due to their design, putting on contact lenses for astigmatism is not the same as putting in other kinds of soft contact lenses: there is a specific way to learn how to put in astigmatism contacts.
Types of astigmatism
Not all astigmatisms are the same. The types of astigmatism creating the refractive error can be categorized according to where the corneas refract the light in the eye.
- Simple Myopic Astigmatism: occurs when light is brought to two focal points -- one on the retina and one before.
- Simple Hyperopic Astigmatism: occurs when light is brought to two focal points -- one on the retina and one behind.
- Compound Myopic Astigmatism: occurs when light is brought to two focal points before the retina at two different locations.
- Compound Hyperopic Astigmatism: occurs when light is brought to two focal points behind the retina at two different locations.
- Mixed Astigmatism: as the name might suggest, occurs when light is brought to two focal points -- one before the retina and one behind.
Besides the different types of astigmatism, the condition can also vary in severity from mild to extreme, where those with mild cases of astigmatism may not even perceive any problems in their eyesight. If you have moderate to extreme astigmatism, you will require corrective lenses in order to see clearly.
Contact lenses for astigmatism
Depending on the degree of severity of the astigmatism, eye doctors may recommend different treatment options for vision correction. For more moderate cases, doctors may prescribe the use of corrective lenses like Acuvue Oasys for astigmatism or Biofinity Toric to correct vision. In cases of extreme astigmatism or other complications, toric soft contact lenses may not be an option to correct vision. Instead, doctors may prescribe the use of rigid gas permeable lenses.