I was catching up on my TV shows and recently watched the much anticipated interview of Hillary Clinton and Barack Obama on 60 minutes a few days after his 2nd Presidential Inauguration. I couldn’t help but notice the glare from the studio lights on Hillary’s left lens of her glasses. When I looked a little more closely, I realized the glare was due to the fact that she had fresnel prism on her lens.
What is fresnel prism and why do we prescribe it?
Prism is added to a patient’s prescription when they experience double vision because it helps shift images together by bending light. Prism can be permanently ground into eyeglass lenses and would not be noticeable to most people. Fresnel prisms are made of up several tiny prisms lined up base to apex on a piece of thin adhesive plastic. They are temporary press-on prisms that come in a variety of powers. It is used in cases when the amount of prism needed is anticipated to change over time because it is much more economical than making an entire new lens every time there is a change.
Hillary Clinton’s double vision caused by her concussion will get better over time, and that is likely why she has temporary fresnel prism on her glasses.
If you are experiencing double vision, it is always a good idea to seek help from your eyecare professional as soon as possible.