Mobile refractive screening technology yields real-world applications

Take-home message: The advent of portable autorefractor technology may deliver autorefraction to populations that might not otherwise have any access to eye care.

By Tal Raviv, MD, FACS, Special to Ophthalmology Times

New York-With a small, mobile platform, autorefractive technology (SVOne Pro, Smart Vision Labs) allows virtually anyone capable of operating a mobile device to conduct an autorefraction, potentially opening the door to providing refractive screening virtually anywhere in the world, or just outside office walls.

The 1-pound, hand-held, smartphone-based autorefractor utilizes Hartman-Shack wavefront aberrometry. This update to the first version of the unit adds expanded measurement parameters and enhanced usability. The SVOne Pro allows the operator to see the patient’s eye when aligning the pupil, and once a good Shack-Hartmann grid is present, the software automatically records three autorefraction measurements. All of this is accomplished within 3 seconds per eye. The SVOne Pro has a spherical range of -14 to +14 D and cylindrical range of -7 to +7 D.

The SVOne Enterprise includes all the features of the SVOne Pro, but is a patient-directed vision testing station. In other words, patients can autorefract themselves using onscreen and voice prompts.

Clinical use

The device sits atop on a tripod/stand. First the device takes a photo of the patient and asks a series of patient history questions, then guides the patient through each eye’s measurement, and finally it displays the result-which can be printed or sent to a HIPAA-secured cloud account.

Most millennial patients easily performed their own refractions without any assistance; basically, anyone who can take a “selfie” can operate the unit. Once they completed the exam, and saw their refraction, most patients had a “wow” response and described the experience as “cool.” A few older patients who were able to operate it did so with mixed reactions and results.

Exam findings generated from the self-administered refraction tests were compared with the in-office legacy autorefractor and subjective exams. The results matched well for young healthy eyes, with occasional outliers. Accommodation must be controlled for with all autorefractors, and the device’s open-field design allows the patient to look in to the distance during the test. A recently published clinical study on the SVOne reported refractive measurements (in visually normal, young individuals) that were not significantly different from four other subjective and objective procedures.¹

Real-world implications

The potential of these low-cost, portable diagnostic instruments is large, and is just the tip of the iceberg of what is possible. There are already smartphone attachments in development for lensometry, subjective visual acuity, and indirect ophthalmoscopy/fundus photography.

The platform may eventually measure higher-order aberrations, and perhaps even perform topography.

Its portability increases access and can help bring refractive eye care to underserved populations around the globe and here in the United States. Domestically, future versions of this device may be of value for school vision screenings, mobile medical services, pediatric medical practices, or nursing homes to name a few.

Future versions of the self-guided, vision-testing station could become integral to the burgeoning realm of telemedicine. Imagine a refractive vision-screening kiosk next to the blood pressure testing kiosk in pharmacy retail locations. Significant refractive errors can be evaluated by eye-care professionals from any location, and follow-up service can be provided or recommended as needed.

Theoretically, the device will become small and inexpensive enough to ship to consumers who could perform their own refraction and send the device back (or purchase it).

Possibilities large, limitations exist

Subjective manifest refinement of autorefraction data is the standard of care in the United States, as is a comprehensive eye examination for pathology. This technology is not going to replace autorefractors that are currently in physician’s practices, or comprehensive exams that all patients should undergo. In the near term, this technology may bring autorefraction to populations who might not otherwise have access to eye care.

Though in its infancy, this technology is promising in that it has real-world applications, and will only get better.

Reference

1. Ciuffreda KJ, Rosenfield M. Evaluation of the SVOne: A handheld, smartphone-based autorefractor. Optometry and Vision Science. 2015;92:1113-1139.

Tal Raviv, MD, FACS

P: 212/889-3550

Dr. Raviv is founder and medical director, Eye Center of New York. He did not indicate a proprietary interest in the subject matter.