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Validation of an Affordable Handheld Wavefront Autorefractor

Rubio, Marcos MSc1,2; Hernández, Carlos S. MSc1,2; Seco, Enrique MD1; Perez-Merino, Pablo OD, PhD3; Casares, Ignacio MEng1,2; Dave, Shivang R. PhD2; Lim, Daryl PhD2; Durr, Nicholas J. PhD2,4; Lage, Eduardo PhD1,2*

doi: 10.1097/OPX.0000000000001427
ORIGINAL INVESTIGATION
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SIGNIFICANCE There is a critical need for tools that increase the accessibility of eye care to address the most common cause of vision impairment: uncorrected refractive errors. This work assesses the performance of an affordable autorefractor, which could help reduce the burden of this health care problem in low-resource communities.

PURPOSE The purpose of this study was to validate the commercial version of a portable wavefront autorefractor for measuring refractive errors.

METHODS Refraction was performed without cycloplegia using (1) a standard clinical procedure consisting of an objective measurement with a desktop autorefractor followed by subjective refraction (SR) and (2) with the handheld autorefractor. Agreement between both methods was evaluated using Bland-Altman analysis and by comparing the visual acuity (VA) with trial frames set to the resulting measurements.

RESULTS The study was conducted on 54 patients (33.9 ± 14.1 years of age) with a spherical equivalent (M) refraction determined by SR ranging from −7.25 to 4.25 D (mean ± SD, −0.93 ± 1.95 D). Mean differences between the portable autorefractor and SR were 0.09 ± 0.39, −0.06 ± 0.13, and 0.02 ± 0.12 D for M, J0, and J45, respectively. The device agreed within 0.5 D of SR in 87% of the eyes for spherical equivalent power. The average VAs achieved from trial lenses set to the wavefront autorefractor and SR results were 0.02 ± 0.015 and 0.015 ± 0.042 logMAR units, respectively. Visual acuity resulting from correction based on the device was the same as or better than that achieved by SR in 87% of the eyes.

CONCLUSIONS This study found excellent agreement between the measurements obtained with the portable autorefractor and the prescriptions based on SR and only small differences between the VA achieved by either method.

1Department of Electronics and Communications Technology, Universidad Autónoma de Madrid, Madrid, Spain

2PlenOptika, Inc., Cambridge, Massachusetts

3Ophthalmology Department, Fundación Jimenez Diaz Hospital, Madrid, Spain

4Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland

*eduardo.lage@uam.es

Submitted: March 26, 2018

Accepted: June 12, 2019

Funding/Support: Seeing Is Believing grant (to SRD); PlenOptika Inc. (to EL); and Spanish Ministerio de Economía y Competitividad (Ramon y Cajal; to EL).

Conflict of Interest Disclosure: NJD, SRD, DL, and EL are inventors on patents related to the autorefractor used in this study. EL, MR, CSH, and IC are funded through grant agreements between Universidad Autonoma de Madrid and PlenOptika Inc. NJD, SRD, DL, EL, and CSH have a financial interest in PlenOptika, Inc.

Study Registration Information: Ensayo y evaluación de dispositivo de bajo coste para la medida de errores refractivos [Test and evaluation of a low cost device for the measurement of refractive errors]/Medical School of the Universidad Automona de Madrid/Comité de Ética en Investigación Clínica 170501.

Author Contributions and Acknowledgments: Conceptualization: DL; Formal Analysis: MR, ES, SRD, DL, EL; Funding Acquisition: SRD, DL, EL; Investigation: MR, CSH, ES, PP-M, NJD, EL; Methodology: MR, ES, PP-M, NJD, EL; Project Administration: PP-M, EL; Resources: IC; Software: CSH, IC, EL; Supervision: PP-M, DL, EL; Validation: CSH, ES, IC, SRD, NJD, EL; Visualization: ES, PP-M, IC, EL; Writing – Original Draft: MR; Writing – Review & Editing: CSH, PP-M, SRD, DL, NJD, EL.

The authors wish to thank Professors Susana Marcos and Carlos Dorronsoro from VioBio Lab (Instituto de Óptica Daza de Valdes, Consejo Superior de Investigaciones Científicas, Spain) for providing access to some of the equipment used in this study.

© 2019 American Academy of Optometry