How Can You Tell if Your Glasses Have High-Index Lenses?

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  • Thread starter Thread starter driedupfish
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SUMMARY

This discussion focuses on identifying high-index lenses for eyeglasses, specifically those with indices of 1.56 or 1.60. The user expresses concern over the thickness of their lenses, which measure approximately 5 mm at the edges, despite requesting high-index options. Key indicators of high-index lenses include the lens curvature and the presence of "rings" on the edges, which can suggest a flat front surface. The user notes a lack of accessible technical information regarding high-index materials, particularly those rated n = 1.70 or 1.74.

PREREQUISITES
  • Understanding of lens indices, specifically high-index lenses (n = 1.56, 1.60, 1.70, 1.74)
  • Knowledge of lens curvature and its impact on thickness
  • Familiarity with optical terminology, including sphere and cylinder measurements
  • Awareness of the differences between plastic and high-index lens materials
NEXT STEPS
  • Research the properties and benefits of high-index lenses, focusing on n = 1.70 and n = 1.74
  • Learn about lens curvature and its effect on thickness in eyeglass lenses
  • Explore optical resources or databases that provide technical specifications for lens materials
  • Investigate the differences between single-curve and double-curve lens designs
USEFUL FOR

Opticians, eyewear consumers, and anyone interested in understanding the characteristics and specifications of high-index eyeglass lenses.

driedupfish
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Recently, I purchased a pair of glasses from a privately owned optic store. I specifically asked for hi-index lens (1.56 or 1.60, I am not sure). The lens I got, however, is kind of thick (around 5 mm thick on the edges).My eye -sight is poor though, -5.00 sphere, -1.25 cylinder on the worst eye. Are there ways to tell if the lens is high-index or just plain regular lens, besides the thickness? Also, there are "rings" on the edge when I look parallel to the surface of the lens.
 
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one reason the lens could be thicker than you expect is if the front surface is flat- some plastic lenses only have one curved surface. This increases the thickness.

I was not able to easily find any technical information about "high index" eyeglass material. I found a few ads claiming n =1.70 or 1.74, but without quantitiatvie information it's hard to separate fact from fantasy.