A Guide to High Index Lenses

The worse your eyesight, the thicker your eyeglass lenses are and this has a major impact on the appearance of your spectacles. Now there is a solution to soda bottle glasses. Enter high index lenses. Thanks to technology and new plastic materials, these lenses are thinner, lighter and look good in any frame even if you suffer from extreme farsightedness, nearsightedness or astigmatism. 

What is High Indexing?

So what are high index lenses? First, let’s get technical. The index of refraction refers to the way a given material bends light. Lenses in glasses remedy refractive errors and your prescription indicates the amount of refraction needed for clear vision. High index lenses bend the light more effectively and at steeper angles than their traditional counterparts. The lenses need less material and curvature. 

Regular plastic lenses have a refractive index around 1.50 while glass lenses are around 1.52. High index lenses have refractive indexes that range from 1.53 to 1.74. Patients often ask, “How thin are high index lenses?” Consider this: Those with an index of 1.70 can be over 50 percent thinner than regular index plastic lenses. The type of high index lens will depend on your prescription but the rule of thumb is the strongest prescriptions usually get the highest index lens.

High Indexing Benefits

Patients with myopia, or nearsightedness, need lenses that are thicker on the edge. If you’re farsighted, your lens is thicker in the middle and thins out toward the edge. The thickness increases with strong prescriptions. This isn’t the case with high index lenses. Consider the benefits:

  • The lenses are thinner than conventional lenses in the same prescription.
  • They improve the cosmetic appeal of your eyeglasses. Even if your prescription is 3.00 +/- or more, you can wear styles like rimless frames without worrying about the heavy appearance.
  • High index lenses are lighter as they use less material, which makes them more comfortable.
  • The lenses are flatter and often have an aspheric design. This minimizes the “bug-eye” effect sometimes seen when individuals are severely farsighted.
  • High index lenses have built-in UV protection.

High index lenses are most effective for prescriptions +/-3.00 D or more. Because they reflect more light than traditional lenses, high index lenses do require anti-reflective lens coating, known as AR coating. The Spectacle Shoppe can help. Stop in and we’ll help you find the best high index lens and coating to suit your needs and budget.

Morgan Nahanee
Morgan Nahanee


Morgan is The Spectacle Shoppe’s Lead Technician and Customer Relations Specialist as well as a Principle of Spectacle Shoppe. She is a licensed contact lens fitter and dispensing optician and has been working for The Spectacle Shoppe since 2006. She graduated from Douglas College’s two year Dispensing Optician and Contact Lens Fitting Program in 2008. From contact lens fitting to eyeglass repairs and adjustments Morgan is eager to help you with any optical needs. Connect with Morgan Nahanee on Google+