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High index lenses are glasses lenses that are thinner and lighter than standard options. As a result, they may benefit people with stronger prescriptions who might otherwise have heavier, thicker lenses.

An estimated 150 million people in the United States have a refractive error. The four most common types of refractive error are:

  • astigmatism
  • myopia (nearsightedness)
  • hyperopia (farsightedness)
  • presbyopia (age-related farsightedness)

People with refractive errors often require stronger prescriptions. They may, therefore, benefit from using high index lenses.

In this article, learn more about high index lenses, what to consider when choosing them, and where to purchase them.

Glasses and contact lens prescriptions contain different numbers and abbreviations. When looking at a prescription, a person will likely notice the following information:

  • OD: This stands for oculus dexter and refers to the right eye.
  • OS: This stands for oculus sinister and refers to the left eye.
  • OU: This stands for oculus uterque and refers to both eyes.

Displayed after each of these letters will be a numerical value with either a plus (+) or minus (-) sign. The higher the number, the more correction a person’s eye needs. The plus sign indicates that a person is farsighted, and the minus sign indicates that a person is nearsighted.

CYL and axis

If a person’s eye has an unusual curve, values are added for cylinder (CYL) and axis.

The eye is usually spherical, but a new curve can develop and change the eye shape. The CYL indicates how much curve is present. The axis indicates where the curve appears on the eye.

A person may need similar correction in both eyes or different corrections in each eye.

High index lenses are made using a type of plastic that bends light more efficiently than other common types of lenses. The result is a lighter, thinner lens that more easily fits inside regular frames.

If a person’s eyesight prescription shows a higher number after the plus or minus sign, they have what is called a strong prescription, which typically also means that they have thicker, heavier glasses lenses that need a more durable frame. This can restrict a person’s choice when looking to purchase new glasses.

High index corrective lenses bend light more efficiently than standard lenses, allowing for a thinner, lighter lens option. This makes it easier to fit them inside regular frames and opens up a wider selection of glasses.

Those with a weaker prescription can also purchase high index lenses, as they are often lighter than traditional lenses.

High index vs. regular lenses

The table below shows a comparison between standard lenses and high index lenses:

Regular lensesHigh index lenses
Thicker lens materialThinner lens material
HeavierLighter
Standard light-bending capabilitiesMore efficient light-bending capabilities
More durableMore fragile
Fewer frame optionsMore frame options
More affordableHigher cost

All glasses lenses work by bending light, and how quickly the light travels through the lens is known as the refractive index.

The refractive index generally defines the type of high index lens a person has. Plastic lenses, known as CR-39, have a refractive index of 1.5. High index lenses have a refractive index of 1.53 to 1.74.

Polycarbonate, which has a refractive index of 1.59, offers a mix of strength and thinness. Many companies offer polycarbonate lenses for an additional fee.

Lenses that are 1.74 are the thinnest lenses a person can purchase. Typically, only people with very high prescriptions use these. They are often the most expensive option.

Not everyone needs high index lenses, and some online retailers discourage people with prescriptions of less than +/-6.00 from purchasing lenses that are 1.74.

Some factors that a person may like to consider before purchasing expensive, high index upgrades include:

  • Aesthetics: A thinner lens can help reduce the magnifying effect of a person’s eyes, leading to a more natural look.
  • Cost: High index lenses are often an added feature at many online and traditional retailers.
  • Weight: Wearing regular lenses with stronger prescriptions may become uncomfortable due to their size and weight.

The following are some online retailers offering high index lens options.

GlassesUSA

GlassesUSA offers several different frame and color options, including ones from brand-name designers. In addition to glasses, it can also fulfill contact lens prescriptions. Its thinnest lens goes up to 1.67.

Other features and services include:

  • frequent sales and promotions
  • several lens and frame customization options
  • direct billing with some health insurance providers
  • a prescription scanner for matching a person’s current glasses
  • a 14-day return period
  • free standard shipping

EyeBuyDirect

EyeBuyDirect offers a large selection of frames to accommodate prescription and non-prescription lenses. A person can choose their frames, color, and any added features for their lenses.

Some other features include:

Lensabl

Lensabl offers several brand-name frames and styles of eyewear. In addition, it offers 1.67 and 1.74 high index options for prescriptions over +/-4.00.

Some other services include:

  • multiple lens coatings
  • online eye exam for those who need to update their prescription
  • free standard shipping
  • replacement items if necessary due to manufacturing errors

Pair Eyewear

Pair Eyewear is a boutique glasses shop that primarily caters to children. The majority of its lenses are polycarbonate with added scratch resistant, UV, and antireflective coatings at no extra charge.

The company also offers:

  • lenses from -9.00 through +6.00, plus higher prescriptions for an added cost
  • frames featuring themes from child-friendly popular culture
  • a 30-day return policy
  • free standard shipping

Pair Eyewear also accepts HSA or FSA payments.

Payne Glasses

Payne Glasses can accommodate high index lenses up to 1.74. It offers a variety of different style frames and colors. Each of its lens options can also include extras such as transitions, which react to different lighting levels, and coatings, which help protect the lenses.

Some additional features and services include:

  • prices starting below $10 on several frames
  • adult’s and children’s styles
  • the ability to make any frame into sunglasses
  • shipping that starts at $5
  • a 30-day return policy
  • use of FSA and HSA accounts

Like glasses, contact lenses can accommodate higher prescriptions. The American Optometric Association says that a person may prefer contact lenses because:

  • They provide better and more natural eyesight.
  • They are more convenient during physical activities and sports.
  • They do not fog.
  • They offer a more natural field of vision.

However, when using contact lenses, there are safety considerations to make. To protect the contact lenses and one’s eyesight, the Centers for Disease Control and Prevention (CDC) recommend that a person:

  • Wash the hands before handling their contact lenses.
  • Store the contact lenses in a clean container with fresh solution.
  • Clean and replace contact lenses regularly.
  • Keep to all scheduled checkups with an eye doctor.

High index lenses are lighter and thinner than traditional lenses. They can be a good choice for people with stronger glasses prescriptions.

Some disadvantages can include added costs.

A person with a lower prescription may find that polycarbonate lenses offer a sturdy, thinner option that is better for those who are very physically active.