What is Astigmatism?
Astigmatism
Astigmatism occurs when the cornea is shaped more like an oblong football than a spherical baseball. An astigmatic cornea has a steeper curve and a flatter one, causing light rays to focus on two points in the back of your eye, rather than on just one, causing blurred vision at all distances.
Until now, people with astigmatism have had only two choices for contact lens wear: “hard” or soft toric contact lenses. “Hard” lenses offer crisp, clear vision but are often irritating and uncomfortable. Soft toric lenses have a reputation for comfort but sometimes rotate, causing inconsistent vision.
Soft Toric Contact Lenses
Most people with astigmatism cannot wear standard soft contact lenses, because standard, or spherical, soft lenses have the same power all around the lens. Toric lenses are made from the same material as soft contacts but are designed differently.
Toric lenses have two powers in them, one for astigmatism, the other for either nearsightedness or farsightedness. To correct your vision, the two powers need to remain stable so toric lenses can’t rotate on your eye. To do this, they are designed so that the bottom portion of the lens is weighted slightly so the lens stays fairly stable when you blink or shift your gaze. However, most toric lens wearers still experience some lens rotation on blink or gaze shift, known as “toric lens rotation,” which results in temporarily blurred vision. This unstable vision can occur anytime and is often more noticeable in lower levels of illumination, such as driving at night.
“Hard” or Gas Permeable (GP) Lenses
With “hard” lenses, or GPs, the lenses’ rigidity can help mask a need for an astigmatic correction: when GP lenses are placed on the astigmatic cornea the space between the back of the GP lens and the surface of the cornea is filled up by tears. This layer of tears functions to correct the astigmatism, so a GP contact lens needs to have only one power to correct any near or far sightedness.
The downside to GP lenses is their less-than-optimal comfort due to the stiffness of the lens material. Rigid lens wearers also experience the irritation of debris collecting under the lens, and may dislodge during activity.
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What is Farsightedness?
Farsighted (hyperopia)
If you are farsighted (hyperopic) you have difficulty seeing objects close-up, which is the result of light rays focusing behind the retina rather than on it.
If you’re farsighted, your prescription begins with a plus number. The higher the numeral, the stronger your lenses will be. Farsightedness can be corrected with glasses or contact lenses.
- “Hard” (rigid gas permeable) lenses are best for providing crisp, clear vision, especially for people with higher amounts of hyperopia. However, hard lenses are often irritating and uncomfortable. Rigid lens wearers also experience the irritation of debris collecting under the lens, and rigid lenses move when you blink and may dislodge during activity.
- Soft lenses are the most comfortable to wear, but often provided soft, fuzzy vision. For people with higher amounts of hyperopia, soft contact lenses may not provide enough correction to deliver good vision.
Ready to optimize your contact lens experience?
No matter what type of contact lenses you currently use, there’s a good chance you’re compromising on either clarity or comfort. Now a technological breakthrough makes having to choose a thing of the past.
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What is Nearsightedness?
Nearsighted (myopia)
If you are nearsighted (myopic) you have difficulty seeing objects that are far away which is the result of light rays focus in front of the retina, rather than on it.
If you’re nearsighted, your prescription is a negative number. The higher the numeral, the stronger your lenses will be. Nearsightedness can be corrected with glasses or contact lenses.
- “Hard” (rigid gas permeable) lenses are best for providing crisp, clear vision, especially for people with higher amounts of myopia. However, hard lenses are often irritating and uncomfortable. Rigid lens wearers also experience the irritation of debris collecting under the lens, and rigid lenses move when you blink and may dislodge during activity.
- Soft lenses are the most comfortable to wear, but often provided soft, fuzzy vision. For people with higher amounts of myopia, soft contact lenses may not provide enough correction to deliver good vision.
Ready to optimize your contact lens experience?
No matter what type of contact lenses you currently use, there’s a good chance you’re compromising on either clarity or comfort. Now a technological breakthrough makes having to choose a thing of the past.
To learn more about SynergEyes, click here.