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Confused as to why I have been prescribed prism in glasses

I'm 28 years old and I recently had an eye exam and found that my new prescription contains prism 1.00 IN on my right eye. I have never had this before. My eyesight is not bad at all and only really need glasses for computer/TV/driving, I think I see quite clearly. I have been reading up on the internet and prism are used to correct double vision, I don't have that. The optician also stated that I need 3 prism's in my right eye to correct it but he was only going to prescribed one so as my eyes would also do some work. Also he tested my right eye with a laser beam going through a white dot but did not do the same test with the left. I am completely confused as to why I need a prism and why wasn't my left eye tested as well?
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  • Charley


    The prism is used to correct a muscle imbalance between the two eyes. It is also used to correct double vision if necessary, but more often used for simple muscle imbalances. The amount of prism you have been prescribed is small and should help your eyes coordinate better together. This should give you more comfortable vision. I would not be concerned about it. I think the other test is the maddox rod test, where a red (or green) streak of light is created in one eye using a special lens (it looks like a laser light, but isn't) and the other eye sees a small dot of white light. This is used to measure the degree of muscle balance....the amount of prism needed to line up the red streak with the spot of light is a measure of the imbalance.