An Autorefractor is an instrument that objectively determines a patient's prescription without requiring any input from the patient.
Q&A With Insight Eye Care on the Autorefractor
Q) Please describe what the Autorefractor is used for and give a basic sense of how it works.
is an instrument that objectively determines a patient's prescription by calculating the curvature of the front surface of the eye, and measuring the length of the eye, resulting in a very accurate calculated lens prescription, without requiring any input from the patient. It's very useful as a starting point for the final prescription determination by means of the phoropter. It's also useful in non-responders, such as small children or handicapped patients.
Q) Isn't a phoropter used to measure refractive error and determine a person's prescription, why is an autorefractor necessary?
The phoropter, by comparison, uses subjective techniques to arrive at the most accurate prescription. Late generation auto-refractors can be extremely accurate, but should not replace the phoropter. Some places in Asia use the auto-refractor results to prescribe glasses, for a reduced fee. This results in a prescription that can be pretty good, but not nearly as accurate as one determined by a phoropter.
Q) Beyond helping in the determination of a prescription, can an autorefractor help discover eye diseases and disorders?
An autorefractor by itself doesn't uncover underlying disease. The instrument we bought (the Topcon KP-8000PA) also has a built-in keratometer and topographer. The keratometer measures the curvature of the cornea centrally for contact lens fitting. The topographer does a wide-spread measurement (10mm diameter) of the cornea and forms a topographical map, showing corneal irregularities, such as keratoconus, and other corneal degenerations. Our instrument also aids in contact lens fittings by simulating the fit of gas-permeable rigid contact lenses and the tear layer between the lens and the patient's cornea.
Q) What is it about this particular technology that you find most exciting; the component that made you feel you need to invest in this for your practice?
The convenience of having all three procedures available in one instrument. We can now do topography on every patient, not just on those we suspect of corneal disease. We can uncover unsuspected pathology this way.
Q) Can you describe the patient experience when using the autorefractor?
The patient focuses straight ahead on a picture of a farmhouse, which appears to be at a great distance. This just has the effect of having the patient relax the eye's focusing. The instrument then blurs the image and calculates three times the curvature of the cornea and length of the eyeball, the average resulting in the lens prescription, the corneal curvature readings, and the topography. It takes about 5-10 seconds per eye. There is a shorter version of this test for kids with low attention spans.
Q) Do the patients that walk through your doors day in and day out, appreciate the upgrade in technology?
We hear from patients all the time that we've done tests that they've never had at other places, and they remark on the new equipment frequently. They feel they're getting the most complete eye exam ever using the latest technology.
Q) To what patients do you recommend using the autorefractor, or is it a part of every eye exam?
It's part of every exam, and is included in the exam fee.