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Polarized sunglasses – what are they?

June 24, 2012

I get this question every now and then from my patients: Should I wear polarized sunglasses?

What are polarized sunglasses?

This refers to a type of lens that can block light rays in one meridian and let in light rays of the other meridian 90 degrees to the one being blocked. Take a look at the diagram below. Light rays come in both horizontal and vertical meridians. Hold up a polarized lens – it will block the light of one meridian, the lens on the top of the diagram lets in light of the vertical meridian. Turn this same lens 90 degrees and it will let in light of the horizontal meridian. Hold up 2 lenses – one held vertically and the other horizontally and stack them together, this will totally block off all light.

Image from whatis,tech target,com

This video link will show you what I just mentioned in words:  Test of polarization.

The first part of the video shows how all light is blocked when you look through 2 polarized glasses held at 90 degrees to each other. The second part of the video shows how light still goes through non-polarized glasses.

When should I use polarized glasses?

Polarized glasses are great when used to view reflective surfaces. They reduce the glare from such surfaces and allow a person to see better. Here are examples of some activities when polarized sunglasses will come in very useful:

  1. Driving on wet roads
  2. Fishing
  3. Boating
  4. Skiing

This video shows you how you can view objects in the water better as polarized sunglasses reduce the reflection coming from the surface of the water: Video on how polarized sunglasses help in fishing.

Should I used polarized sunglasses after LASIK?

I recommend all my patients to use sunglasses after LASIK. It does not have to be polarized. More importantly, it should block ultraviolet light well. Read my other article on sunglasses and UV light.

Do you used sunglasses? What do you use them for?
Feel free to comment or to ask questions.

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2 Comments leave one →
  1. July 6, 2012 11:31 pm

    Hugely useful info for me. Always wandered what these glasses were about and if I should have them. Thanks

    • July 7, 2012 7:41 am

      Hi Ben, thanks very much for your comment. You are most welcome. Glad to hear that it is useful info for you. 🙂

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