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Inside Your Eye Exam: What is a Phoropter?

Posted on April 11th, 2017

If you've ever had an eye exam, chances are you've been up close and personal with a phoropter (even if you aren't exactly sure of its name). The device, which fits over your head and looks like a strange alien mask or a mechanical butterfly, has been a mainstay in optometrist offices around the world for decades.

But what exactly is a phoropter and how does it work? More importantly, how does it help your vision?

To answer those questions, you must first consider why it is used by eye doctors. By having you look through the phoropter at a visual reference (such as an image on a wall or an eye chart), your optometrist will rapidly test your sight by switching lenses until you find one that allows you to see the clearest. Each one the doctor asks you to look through is used to manually determine the level of "refraction," or how curved and uniquely shaped a lens must be to compensate for your eyes' vision requirements. In addition to detecting refraction issues, a phoropter also allows a doctor to check binocular vision function and determine how well the muscle coordination is in your eyes.

It's important to note that phoropters are subjective since your responses will impact the test. This is because your optometrist makes adjustments based on your responses. "Is your vision better or worse? Is it clearer with the first lens or the second one?"

Phoropters offer objective findings when combined with tests, such a retinoscopy (which is particularly useful for young children and patients who cannot communicate well). As an alternative, a device known as an autorefractor automatically detects prescriptions. However, in some cases, the phoropter can be more accurate since automated devices sometimes over-accommodate prescriptions.

Ultimately, the phoropter is a unique piece of medical equipment used by your eye doctor. It offers not only valuable insight into your vision but also allows you to take an important role in helping diagnose the overall health of your eyes.

To get up close with the phoropter, book your next eye exam at an FYidoctors near you.