Glass or Plastic Lenses?

  • 25 June 2018
  • Troy Cassidy

The overwhelming majority of spectacle lenses produced for consumers both in NZ and worldwide are made of various types of plastic.  Plastic lenses have a number of advantages over glass:

  • Lighter weight
  • Safety
  • Easier for optical laboratories to manufacture

The first two advantages of plastic lenses are obvious: we all know that plastic lenses are significantly lighter than their glass equivalents, and the safety advantage of plastic versus the danger of impact-shattered glass is equally clear. 

The third advantage is less obvious, but it refers to the ability of optical labs to shape the complex curves of many modern lens designs onto a lens blank.  These sophisticated lens designs reduce distortion, and make a pair of lenses more comfortable to wear.  Glass is an unforgiving material, and it is difficult to shape a glass lens blank in these complex shapes.  This means that glass progressive lenses are based on older technology, and may not provide as comfortable a wearing experience as a modern progressive lens.

However, glass lenses remain an important niche product.  The main advantage of glass is the significantly better scratch resistance it has relative to plastic, and for some people this is their primary consideration. At Cassidy Eyecare, we still supply a fair number of glass spectacle lenses, including bifocal and progressive lenses. 

We order all our glass lenses to be put though a special toughening process, which improves the safety of the lenses.  Our local labs are able to supply glass lenses in pretty good time, and the pricing of glass lenses is very similar to plastic.

If you would like the ultimate scratch-resistance of glass lenses for your spectacles, give us a call.  

About Troy Cassidy

Troy graduated from the University of Auckland Optometry programme in 1995, and has worked in optometry practices in NZ, Australia & the UK since then. Along with wife Stephanie, he has owned and operated Cassidy Eyecare in west Auckland since 2010.

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