When autorefractors first came on the scene in the first 1970s, they’d difficulty achieving true refraction because of problems with accommodation, accuracy, and the general speed of the test. Today, manufacturers address each of these problems, as auto refractors and keratometers get faster and come closer than ever to the outcomes obtained with subjective refraction.
Peter Leadem of Lombart Instruments’sales division said that while manufacturers share the target of the autorefractor learning to be a sufficient replacement for the subjective method, the odds are fairly remote. “Every manufacturer is working to bring autorefractors as close to the final Rx as possible,” he told Primary Care Optometry News. “There’s probably never going to be always a time when an autorefractor is going to replace the actual refraction a doctor performs.
Everybody is trying to create them faster, so the acquisition speed is quicker, or the printers are quicker. Right now, they’re all great so that manufacturers will work on smaller benefits such as for instance, faster speed and ease of operation.”
Same principles, different technologies
Sue Corwin, CO, COMT, director of education and training at Marco Technologies, told Primary Care Optometry News that the business runs on a unique system to obtain the refraction. Rather than sampling from 180°, averaging the samples, and using an algorithm, she said, the Marco ARK760A employs all 180° with which to pinpoint the cylinder access and cylinder power with greater accuracy.
The instrument has evolved, she said, by striving for the same goals but advancing with progressive technology. The high-speed auto tracking feature, as an example, will track a roving eye until it is in the proper position to take the refraction.
“We have an infinity target for patients to consider, which is important, so they don’t accommodate,” she said. “There’s a little hot-air balloon by the end of a highway, and even though patients move their eyes around, the unit will track them. So if you have someone who’s chewing their dentures or a child is wiggling around, the unit will keep tracking him or her to get the measurement.”
The difference involving the Leica KR450 and earlier models is “like night and day,” Mr. Leadem said. The SR-IV, he explained, was a subjective autorefractor, something that has lost popularity with the advent of objective autorefractors. “Once the SR-IV was out, there is less emphasis positioned on an instrument’s capability to have a good objective autorefraction and more emphasis positioned on the fact that refraction could be refined after the very fact with subjective testing. That’s where that unit earned its success,” he said. “The new units are strictly objective and now involve the keratometer, also.”