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High-Definition Eyeglass Lenses

By Gary Heiting, OD

Do you have 20/20 vision when you wear your glasses but still feel dissatisfied with how you see? You might benefit from high-definition lenses.

Sometimes, higher-order aberrations can affect your vision, even if your prescription eyeglasses fully correct your nearsightedness, farsightedness and/or astigmatism. These aberrations may be due to the optical characteristics of your eyes or can be caused by the optical limitations of conventional eyeglass lenses.

But recent advances in eyeglass lens manufacturing have made possible new high-definition eyeglass lenses that correct these aberrations, potentially giving you sharper vision than what is possible with conventional eyeglasses. These lenses are designed to provide sharper vision in all lighting conditions and reduce glare for nighttime driving and other night vision tasks.

Many brands of high-definition eyeglass lenses currently are available, including high-definition versions of high-index lenses and progressive lenses.

Free-Form Lenses

The most popular type of high-definition eyeglass lenses are called free-form lenses. The term "free-form" refers to an advanced manufacturing process that reduces higher-order aberrations such as spherical aberration that occur in eyeglass lenses created with traditional eyeglass lens manufacturing tools and processes.

With free-form lenses (also called digitally surfaced eyeglass lenses), the fabrication of the lenses from wearer's eyeglass prescription is optimized with advanced manufacturing tools ("surfacing" equipment) that are much more precise than conventional tools. In fact, digital, free-form technology can surface lenses in power intervals of 0.01 diopter (D), compared with 0.125 to 0.25 D increments of conventional eyeglass lens tooling.

The fabrication of some digital, free-form lenses also takes into account how the lenses are positioned in front of the wearer's eyes when in the eyeglass frame when optimizing the lens power.

Other factors that may be considered in the lens customization process include the angle between the eye and the back surface of the lens in different gaze positions (for example, when the wearer is looking off to the side rather than straight through the center of the lens), the frame size and the position of the wearer's pupil within the frame outline.

With these and possibly other factors taken into account during lens design and fabrication, high-definition eyeglass lenses offer an unprecedented degree of customization and may reduce or eliminate certain higher-order aberrations.

The precisely made and personalized surfaces of high-definition lenses may help reduce aberrations that limit field of view and cause starbursts, halos and comet-shaped distortions of lights at night.

The result is that high-definition lenses may provide sharper image quality, better peripheral vision, improved contrast sensitivity and less glare at night.

Popular free-form, single vision lenses for the correction of nearsightedness, farsightedness and/or astigmatism include:

• Essilor 360 DS (Essilor of America)
• Hoya NuLux EP (Hoya Vision Care)
• Shamir Autograph II SV (Shamir Insight)
• Clarlet Individual (Carl Zeiss Vision)

Popular free-form progressive lenses for the added correction of presbyopia include:

• Hoyalux iD MyStyle (Hoya Vision Care)
• Kodak Unique (Signet Armorlite)
• Seiko Supercede (Seiko Optical Products of America)
• Shamir Autograph II (Shamir Insight)
• Varilux Physio DRx (Essilor of America)
• Sola HDV (Carl Zeiss Vision)
• Gradal Individual (Carl Zeiss Vision)

Because creating high-definition lenses requires additional information beyond what is recorded on your eyeglass prescription, your optician usually will take additional measurements when you choose your eyeglass frames.

Sometimes, a proprietary measuring device is used for fitting and fabricating a specific brand of free-form, high-definition lenses.

One example is the Zeiss i.Terminal 2, a photo-capture system that automatically measures several fitting parameters — including the distance between the wearer's pupils (PD), fitting height, tilt of the frame (pantoscopic angle) and distance between the back of the lenses and the front of the eyes (back vertex distance) — to optimize the performance of Carl Zeiss Vision's Individual brand of customized high-definition lenses.

Another example is the Visioffice system — an automated measuring device for customized free-form lenses offered by Essilor and Varilux. The Visioffice system takes into account PD, fitting height, and a 3-D measurement called eye rotation center (ERC) to determine each wearer's unique "eyecode," which enables an optical lab to create single vision or progressive lenses that are designed for the specific visual needs of each person, according to Essilor.

High-definition lenses are designed to provide sharper vision in all conditions and reduced glare for nighttime driving.

Wavefront Lenses

Wavefront lenses are another type of high-definition eyeglass lenses.

These eyeglass lenses are created with the same technology that measures the eyes prior to customized, wavefront-guided LASIK eye surgery. A computerized instrument projects uniform light waves into the eye to measure both refractive errors and higher-order aberrations. These rays reflect off the retina and the returning "wavefront" of light is analyzed.

In custom LASIK, this wavefront analysis programs the excimer laser to precisely reshape the eye to reduce higher-order aberrations. In wavefront eyeglass lenses, the wavefront analysis drives a proprietary manufacturing process to create eyeglass lenses that correct higher-order aberrations as well as common refractive errors.

The first brand of wavefront eyeglass lenses introduced in the United States was iZon High Resolution Lenses, manufactured by Ophthonix. According to the company's website, in simulated nighttime driving tests, subjects wearing iZon High Resolution Lenses were able to detect, recognize and react to a pedestrian along the road an average of 20 feet sooner than drivers wearing conventional lenses when driving 55 mph in glare conditions.

Besides improving night vision for driving, iZon lenses also may benefit people who have lingering vision problems following LASIK and other refractive eye surgery, the company says.

All iZon lenses are made of high-index lens materials for thinner, lighter lenses and include anti-reflective coating. They also can be fabricated as photochromic lenses for greater comfort outdoors in changing light conditions.

In 2011, Carl Zeiss Vision introduced i.Scription by Zeiss wavefront lenses in the United States. Like iZon lenses, i.Scription by Zeiss lenses are designed to correct higher-order aberrations and provide sharper vision than regular eyeglass lenses.

According to the company, i.Scription by Zeiss lenses also help wearers see better in low light conditions and experience improved contrast and color vision.

To prescribe wavefront lenses, optometrists and ophthalmologists first must take computerized wavefront measurements of your eyes using instruments that are proprietary to the lens manufacturer.

For iZon lenses, these measurements are obtained with Ophthonix's Z-View Aberrometer.

For i.Scription by Zeiss lenses, measurements are obtained with Carl Zeiss Vision's i.Profiler Plus — a 3-in-1 automated device that measures refractive error, corneal topography and higher-order aberrations.

The wavefront measurements then are sent to the lens manufacturer or an optical lab to fabricate the custom-made high-definition lenses.

Are You a Candidate for High-Definition Lenses?

Virtually anyone who wears eyeglasses is a good candidate for free-form, high-definition lenses, but individuals with higher eyeglass prescriptions may notice greater benefits than people with only mild prescriptions.

For wavefront lenses, your eye doctor must perform aberrometry measurements to determine if you are a good candidate for iZon High Resolution Lenses or iScription by Zeiss high definition lenses.

Cost of High-Definition Lenses

Because of the sophisticated technology used to design and fabricate free-form and wavefront lenses, these high-definition lenses typically cost 25 to 30 percent more than traditional eyeglass lenses made of the same materials and coatings.

Though costs are higher, some eye care practitioners say people with presbyopia particularly can benefit from high-definition progressive lenses, which may provide sharper, more comfortable vision with fewer adaptation issues, compared with conventional progressive lenses.

[For the latest news about high-definition lenses and other eyeglass lenses, see What's New in Eyeglass Lenses.]

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[Page updated December 2011]