This is the method used to determine someone’s glasses prescription. Most refraction is performed with a phoropter. This is the optical device you look through while reading an eye chart – it contains lenses and can be used to determine your refractive error (nearsightedness and farsightedness) and correct astigmatism.  Refraction requires feedback from our patients, so this technique can be especially tough in children and in non-verbal people (ex.: dementia).  The range of potential refractive error is huge, so it is very helpful to have our patients bring their current glasses in to the office to be measured. These measurements are a starting point for the refraction process. It is also helpful to know the current glasses prescription so that we can advise our patients whether it is “worth it” to update their current spectacles.

Dr. Timothy Root is a practicing ophthalmologist and cataract surgeon in Daytona Beach, Florida. His books, video lectures, and training resources can be found at:


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