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Aspheric lenses are a new optical technology that is improving images from cameras, telescopes, and other optical devices. These lenses are also being applied to personal visual devices, most often glasses. (Learn More)
This type of lens can be made from any material, including polycarbonate and Trivex. Because they have a different, non-spherical design, they can improve how light refracts onto your retina while allowing you to wear a lighter material with less curvature. This means they are less likely to create the “coke bottle glasses” effect. (Learn More)
People who have higher order refractive errors, usually +4.00 diopters or more, benefit the most from aspherical lenses. Reading glasses and contact lenses are also being manufactured with this type of lens, so more people can benefit from clearer vision. (Learn More) Aspherical intraocular lenses (IOLs), which are implanted during cataract removal surgery, are also being recommended to manage refractive errors. (Learn More)
There are a few downsides to aspherical lenses. The main issue is their cost since they take more effort to manufacture. These lenses may also require reflective coatings that traditional lenses do not, and they require accurate measurements of your pupillary distance. (Learn More)
Since these lenses are getting increasingly popular, it is becoming easier to find them online and in brick-and-mortar retailers. Ask your optometrist for a recommendation on where to get these lenses. (Learn More)
Aspheric Lenses: Better Vision & Better Appearance
Aspheric lenses are a thinner, flatter type of lens for glasses. In the past, people who have higher prescriptions have needed thicker lenses to see clearly. Thanks to changes in the materials and technology of glasses, even people who are very nearsighted or farsighted can wear lightweight glasses and thin frames.
This is much more convenient for people who wear glasses. These thinner lenses are more attractive, and they feel better resting on the face.
These lenses are like those used for cameras. Originally, both concave and convex lenses for cameras were designed to represent part of a perfect sphere. However, these lenses cannot project an image that is uniformly focused across a flat surface, even in various combinations. This is because the depth of focus is too narrow. When applied to cameras, aspherical lenses correct these focus aberrations.
Like aspheric camera lenses, aspheric glasses lenses improve the evenness of your focus. Thanks to adaptations in computer models of these lenses and improved manufacturing techniques, aspheric lenses are more common across dozens of applications, including for vision improvement. Many people who need glasses are switching to aspheric lenses for the vision benefits, comfort, and improved appearance.
What Are Aspheric Lenses? How Are They Different From Traditional Lenses?
The term aspheric means “not spherical,” which shows the main difference between these lenses and traditional lenses for glasses. Traditional lenses made from glass or plastic tend to have a slightly bulged shape, mimicking a sphere. These older designs follow a curve like that of your eye’s cornea and lens, to adjust how light is refracted onto your retina.
Traditional lenses can be large and heavy if you have a significant refractive error, like astigmatism, myopia, or hyperopia. Traditionally, lens shapes are:
- Convex, or thicker at the center and thinner at the edges, to improve farsightedness (hyperopia and presbyopia).
- Concave, or thinner at the center and thicker around the edges, to improve nearsightedness (myopia).
When lenses treat higher order vision problems, traditional lenses are thicker in some areas, which creates the “coke bottle lens” effect. Many people find this unattractive and avoid wearing their glasses as a result. They may choose an alternative like contact lenses or LASIK, or they may simply avoid wearing their glasses, which can increase eye strain.
Traditional lenses for glasses are also prone to spherical errors. These imaging errors or aberrations can create slightly blurry images since the light rays do not converge at one single point on the optical axis, which should be your retina. Light rays are refracted at slightly different degrees from different angles, depending on where they enter the eye through the lens. They collect in the general area of your retina, but the light could still be distributed so it does not create a clear image in your brain.
- Marginal astigmatism. This occurs when narrow beams of parallel rays hit your lens at an angle, creating two focus points. This can create an astigmatism effect even if you do not have an astigmatism.
- Distortion. This is when light rays move from the center of the lens to the edges, increasing magnification. This can cause a distortion in your visual field known as the pincushion effect.
- Chromatic aberration. This is when light moving through the lens is dispersed or broken up into component colors. Each wavelength travels at a different speed, causing some objects to appear a slightly different color.
In contrast, aspheric lenses are rotationally symmetric, with one or more nonspherical surfaces that differ from a sphere’s shape. This improves how aberrations are corrected, so light rays are refracted on a more accurate point on your retina.
Who Should Wear Aspheric Lenses?
Anyone with a higher order refractive error can benefit from aspheric lenses. This is typically around +4.00 diopters or higher. Traditional glasses become bulky and heavy because they must be thick enough to correct curvature problems in your cornea or lens. Aspheric lenses can correct these refractive issues more effectively.
Benefits of aspheric lenses include:
- A sleeker profile to your glasses.
- A lightweight material so your nose bridge has less pressure.
- More frame options for people with higher prescriptions because the lenses are not as large.
- A more natural appearance to your eyes since they reduce eye magnification.
- Better image quality because of less magnification.
- Better peripheral vision due to uniform focusing areas.
While people who wear glasses benefit the most from aspheric lenses, contact lens manufacturers are also creating aspheric contacts, offering a similar, lower distortion effect. These are great for people with more active lifestyles who want or need a full range of view, including peripheral vision, which glasses may not correct.
More reading glasses are being made with aspheric lenses too. Although aspheric lenses are recommended for people who need vision correction all the time, reading glasses at lower diopters can also benefit from being aspheric, especially if they are progressive lenses rather than bifocals.
Aspheric Intraocular Lenses (IOLs)
If you have cataracts that obscure your vision, you are likely to be recommended for cataract surgery. This process removes the natural lens of your eye and replaces it with an artificial lens, called an intraocular lens (IOL).
For some people, these lenses can lead to refractive errors even when one did not exist before. This is because they do not refract light as well as a healthy natural lens. It can be difficult to predict how serious the refractive error will be because cataract surgery does not involve mapping the cornea, which refracts light too. If there is a shape change on the cornea, a refractive error can also develop.
Some surgeons offer aspherical IOLs to offset potential refractive errors. A study measured preoperative corneal topography. Then, doctors chose an aspherical IOL based on the existing corneal aberrations, so that the sum of the two values was as close to zero as possible. While some surgeons are skeptical about the precision of aspheric IOL manufacturing measurements, approaching cataract surgery in this way can improve visual acuity outcomes for many people.
Are There Downsides to Aspheric Lenses?
While aspheric lenses are a great option for many people who wear glasses, it is important to make sure the center of the lens lines up with your pupil. Particularly with this type of lens, your vision can become distorted if the pupillary distance is off-center.
Aspheric lenses are also more likely to have reflections, so it is important to get an anti-reflective coating on the lenses. This means that your lenses may cost more than traditional lenses made from plastic. Since aspheric lenses are a specific design or shape and not a type of material, you can get high-quality polycarbonate or even Trivex lenses that are aspheric. These can offer improved visual acuity.
The biggest pitfall with aspheric lenses is their cost. Since there is more precision involved in the manufacturing process, they are harder to manufacture. As they become more common, this cost will likely decrease over time. Right now, spherical lenses are still simpler to make, and they typically cost less.
How to Find Aspheric Lenses
Aspherical lenses are available in many places. If you buy your glasses through your optometrist, ask about aspherical lens options. If you purchase them at a store separately, you can find these options online or at a brick-and-mortar retailer.
Some online retailers, for example, will ask during the glasses ordering process whether you want to upgrade to thinner, aspheric lenses for an additional charge. However, online retailers may not be able to get your pupil distance lined up properly, so purchasing these lenses in person may work better. You can ask a retailer in person about this option.
If you do opt to order these lenses online, confirm the retailer’s return policy if the pupillary distance isn’t correct. You don’t want to be stuck with lenses that don’t work for you. Some online retailers have partnerships with brick-and-mortar stores. You can then visit these locations to get in-person help if something isn’t right with your lenses.
Why Wear Aspheric Lenses? The Fine Print Blog.
Aspherical Lens Element: What Is It and How Does It Work? (November 2014). What Digital Camera.com.
Testing Aspheres. (April 2008). OSA Publishing.
Aspheric Lens. Asphericon.
Aspheric Lenses: Why Recommend One? (February 2016). Opt Magazine.
Benefits of Aspheric Lenses. (February 2019). Medium.
The Pluses and Minuses of Aspheric IOLs. (January 2009). Review of Ophthalmology.
Advantages and Disadvantages of Various Types of Contact Lenses. American Optometric Association.
How to Choose an Aspheric Intraocular Lens. American Academy of Ophthalmology.