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What Are Aspheric Lenses?

Medically Reviewed by Dany Paul Baby, MD on June 26, 2022

Choosing new glasses involves lots of factors, including the type of lens you will purchase. If you have a strong prescription, you might consider aspheric lenses. 

What Are Aspheric Lenses?

There are many types of lenses for glasses, including aspheric lenses. Whereas regular or standard lenses have a circular shape, aspheric lenses have a varying curve across the lens. They’re a thinner, flatter, upgraded lens.

Understanding Light and Vision

Most vision problems occur because of the way light is focused using your retina. The retina is the innermost part of your eye that senses light and helps turn it into three-dimensional images. It works with the cornea, which is the outermost layer of your eye, and the lens, which is an inner part of your eye. 

The cornea and lens bend (i.e., refract) light as it enters your eye and focuses it on your retina. The cornea is fixed, but the lens changes shape as you focus on something close or far away. Your eye or cornea shape, though, can change the way the light bends and cause it to miss your retina or not focus directly on it. These are called refractive errors and can cause blurry vision. 

Refractive errors can cause nearsightedness where you see well up close but have trouble seeing farther away. They also cause farsightedness, where you can see distant objects well but not close ones. You can correct these problems with glasses. The purpose is to put a lens in front of your eye that helps focus light directly on your retina. The result is clearer and more comfortable vision.

Curved Lenses vs. Aspheric Lenses

Most lenses have a consistent curve that helps bring light to a focus. A concave lens curves inward and helps with nearsightedness, while a convex lens curves outward and helps with farsightedness

There are drawbacks, though, if you have a strong prescription with significant curvature. With a stronger prescription, your lenses are thicker and heavier and they can make your eyes look bigger. In these cases, aspheric lenses are a good option.  

Aspheric lenses change the degree of curve from the center of the lens to the outside. The curve is flatter, so the lens is thinner and lighter. 

How do aspheric lenses work?

Because the curve varies and flattens toward the edge of the lens, aspheric lenses have a larger usable area than regular lenses. This larger area means that aspheric lenses can bend light more efficiently than regular lenses. 

In regular lenses, the light that hits the edge of the lens focuses at a different spot than the light at the center. The result is fuzzy vision in your periphery. 

If you have a strong prescription, you’ll need a thick lens to bend the light properly. If you’re farsighted, you’ll need more thickness at the center of your lenses. Your eyes will look magnified and create what’s sometimes called goggle eyes or the soda bottle look. You might feel self-conscious about your glasses and how they make you look, but aspheric lenses can help. 

With a flatter curve, there's less central thickness and less eye magnification. They also correct distortion and create a higher-quality image. 

Aspheric lenses can also improve your peripheral vision. The lens is thinner and lighter, so it can fit better in your glasses frame. 

What Are Aspheric Lenses Used For?

You might want to choose aspheric lenses when you have a strong prescription or you experience dramatic refractive errors. Dramatic refractive errors mean you have significant problems with the way light focuses on your retina, which means you’ll need stronger corrective measures. 

Relevant problems include conditions like:

  • Myopia, where objects in the distance are blurry
  • Hypermetropia, where objects close to you are blurry
  • Astigmatism, where objects near and far are blurry or distorted
  • Presbyopia, where you can’t see things close up as you get older

Your eye doctor might recommend lenses that are both aspheric and high-index. Where aspheric refers to the lens profile, high-index refers to lens material and thickness. The higher the index number, the thinner the lens. 

It’s called a high-index lens because it has a high refractive index, which means light travels quickly through the material. The material bends light more efficiently, making it better at correcting high refractive errors. 

An aspheric and high-index option means your lenses will be easier to wear with a strong prescription. 

Pros of Aspheric Lenses for Glasses

Aspheric lenses will make your glasses lighter, thinner, and more comfortable to wear. Thicker lenses are harder to fit into your glasses frame, and they’re more likely to pop out. If this happens a lot, you’re likely to damage your lenses and frames, which can lead to greater expense. 

Aspheric lenses can fit into most frames, so you can wear almost any style, including rimless or plastic frames. These also avoid distorting the appearance of your eyes and can help you feel confident wearing glasses. 

Cons of Aspheric Lenses

Aspheric lenses can be more expensive to make, which means your glasses will cost more. You might be ready to pay more if it helps your eyes look less magnified, but replacing your current glasses could be expensive. You’ll likely want anti-scratch and anti-reflective coatings, too, which will add to the cost. 

While high-index aspheric lenses have a better profile for strong prescriptions, high-index lenses aren’t impact-resistant. They’re more fragile, so you’ll need to be extra careful with them. 

Bottom Line

Aspheric lenses are a great option for strong prescriptions. They give you more comfort, more access to frame styles, and lessen your eye magnification. These lenses can give you confidence and help you feel good about your personal style. 

Ask your eye doctor if aspheric lenses are a good choice for you. 

Show Sources

SOURCES:

Association of Optometrists: “Your prescription explained.”

Cleveland Clinic: “Eyeglasses.”

International Society of Optics and Photonics Optics.org: “Optical systems benefit from aspherical lenses.”

Johns Hopkins Medicine Wilmer Eye Institute: “Lenses We Offer.”

Mahadbadi, N. Al Khalili, Y. StatPearls, “Neuroanatomy, Retina,” StatPearls Publishing, 2022.

Merck Manual Consumer Version: “Overview of Refractive Disorders.”

National Eye Institute: “Refractive Errors.”

Optometrists Network: “Guide to High-Index Lenses,” “Optical Lenses.”

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