Evaluation of a Novel Self-Refraction Device (USee) to Measure Refractive Error in Adults – A Pilot Study

Abstract

Purpose: To compare refractive error measurements from the USee device to those obtained by conventional refraction in adults. This pilot study evaluated the USee for use in a larger study of US children. Ultimately, it is hoped that the USee can be used to refract and prescribe glasses for patients in developing countries.

Methods: 48 students from the New England College of Optometry with known spherical equivalent (SE) refractive error ≤6.00 diopters (D) myopia or hyperopia, astigmatism ≤2.00D in both eyes were recruited. Subjects underwent autorefraction, self-refraction by the USee device, manifest refraction by the investigator and visual acuity (VA) through U-See pop-in spectacles. All testing was non-cycloplegic. Finally, subjects answered four questions about their experience with the U-See device.

Results: Among the 48 subjects (mean age 25.5 years, 79.2% female) the mean best corrected visual acuity (BCVA) was identical between USee refraction and manifest refraction in the better eye {logMAR VA (SD), -0.1[0.1]} and worse eye {-0.1 [0.1]}. The mean difference in SE between the USee refraction and manifest refraction was 0.16D±0.9D in the right eye, 0.18D±0.9D in the left eye. Mean autorefraction and USee refraction were similar in both eyes (-3.50D±1.5D), and were comparable to the mean manifest refraction in both eyes (-3.30D±1.7D). When questioned about the USee device experience, 94% of subjects said the USee device was easy to use. 98% felt that compared to no correction, the pop-in U-See spectacles improved vision. 48% thought the U-See spectacles worked as well as their current spectacles.

Conclusion(s): Self-refraction with the USee device demonstrates comparable measures of SE and BCVA to that of manifest refraction and autorefraction for low to moderate refractive errors in these subjects. Future directions will focus on the usability of this device in a broader range of ages, including children.