
Contact lenses for Astigmatism
A popular analogy to explain astigmatism is to describe the cornea as being shaped more like the curve of an AFL football, which differs depending on whether you follow the curve sideways or lengthways. As opposed to a soccer ball which is the same spherical surface no matter which direction you follow.
People with astigmatism often experience the following symptoms:
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Blurry vision
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A starburst-type glare of lights, like oncoming car headlights at night
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Headaches and eyestrain
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Ghosting or shadowing of images
How do Contact Lenses for Astigmatism Work?
Nowadays, you have the choice of standard soft lenses, toric design lenses, RGP lenses (rigid gas permeable contact lenses), and more.
In the late 1970s contact lenses for astigmatism, also known as toric lenses, became available. Toric contacts tend to be slightly wider in diameter to other lenses, to help provide better stability.
Eye care is of course of the most important, particularly when it comes to contact lenses. It’s therefore essential that your toric contact lens fits well. If not, they can be unstable on the eye between blinks or eye movements, resulting in fluctuating vision.
The basic principle is varying lens thickness (and weight) across different zones of the lens, taking advantage of gravity to orientate the lens in a specific way on the eye.
Eyelid anatomy and the dynamics of blinking and eye movements vary from individual to individual. One toric lens that fits well on one eye will not fit well on the next.
Intraocular Contact Lenses
A small incision is made in the cornea for the lens to be inserted. Intraocular contact lenses are considered to be a safe and effective method of permanent vision correction.
Options in regular contact lenses are scarce once they exceed -2.75 dioptres of astigmatism. And those few toric lenses available past this degree may have a greater likelihood of being unsuitable for an astigmatic patient.
Implantable contact lenses however can treat astigmatism of up to -4.5 dioptres, myopia of up to -18 dioptres, and hyperopia of up to +8 dioptres.
Intraocular contact lenses are often also a viable option for patients looking into refractive surgery but find themselves falling outside of the parameters of LASIK or PRK. Unlike these procedures, implantable contact lenses do not rely on minimum corneal thickness in order to provide prescription correction.
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