Can Contact Lenses Correct Astigmatism?
What is Astigmatism?
Astigmatism is a very common condition that reduces the eye’s ability to create a focused image. This results in seeing blur at distance and up close.
The cornea or the lens inside of the eye are responsible for creating astigmatism in an eye.
Astigmatism is responsible for any cylinder portion of your prescription and also determines the axis of the prescription.
With glasses, astigmatism can be corrected by having cylinder power written into the prescription and put into the lenses.
Since astigmatism is axis dependent, by placing the glasses lenses into a frame you are setting the axis to properly correct for the astigmatism.
With contact lenses, however, there is no frame to hold the lens in place which can create issues and result in blurry vision.
Hard Contacts for Astigmatism
Hard contacts, also called rigid or GP contacts, can correct for astigmatism in two ways.
One method is by using the tear film between the contact lens and the cornea on the front of the eye to correct for the astigmatism.
In this method, the contact lens is a sphere power only and the same throughout the lens. Once it is on the eye, the lens creates a tear film underneath it and on top of the cornea.
The tear film shape is determined by the cornea and will correct any astigmatism caused by the cornea. If all, or the majority, of the astigmatism is caused by the cornea this method will likely work to correct the astigmatism.
If there is a large amount of astigmatism that is not caused by the cornea, or if there is greater than three diopters of astigmatism, another method must be used.
The other method of correcting astigmatism with hard contacts is to change the shape of the front of the lens to match the needed astigmatism correction.
This method allows to correct for any astigmatism in the prescription and relies on weights in the bottom portion of the contact lens to center it on the eye properly.
Hard contacts were among the first to provide astigmatism correction and are still widely used for this purpose.
Soft Contacts for Astigmatism
Soft contact lenses have developed several methods of correcting for astigmatism. Unlike the hard lenses, there is no tear film between the contact lens and the cornea so there is no way to use this to correct for the astigmatism.
Instead, all of the correction must come from the soft contact lens. These contacts are created with a specific astigmatism power and axis in the contact lens.
The biggest issue with soft contact lenses correcting for astigmatism is the fact that the lenses move and rotate on the eyes.
Some contacts that are developed for astigmatism have created a shape that consistently rotates into one place on the eye allowing for the proper correction of astigmatism.
There are many options available among soft contact lenses that correct for astigmatism.
Toric Contact Lenses and Astigmatism
Despite many changes and advancements in design, the biggest issue with contact lenses correcting for astigmatism remains blurry vision.
Some people with astigmatism cannot get vision as clear with contacts as they can glasses.
If you want to try contacts and have astigmatism, consult your eye doctor and they can begin the process of finding the best contact lens for you.
You can schedule your next appointment with us online!
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