Validation of a portable, remotely delivered refraction approach compared to standard in-clinic refraction in a low-vision population

Introduction: A low-vision assessment (LVA) is critical in developing a vision rehabilitation plan. A remotely delivered LVA that replicates a standard in-clinic assessment may bridge the gap for patients not accessing care due to the limited quantity and distribution of low-vision providers. Within an LVA, an accurate and consistent assessment of refraction error is an essential component. No system has currently been validated for the purposes of a remote LVA. The purpose of this study was to validate a commercially available portable refraction approach in a low-vision population.

Methods: Low-vision patients (n = 26) or normally sighted patients (n = 25) underwent a refraction assessment using the Adaptica® 2WIN autorefractor, adaptor scope (Kaleidos) and VisionFit phoropter portable refraction devices, as well as a standard autorefractor (Huvitz) and phoropter (Haag-Streit). Refraction data between systems and populations were compared using intraclass correlations. Bland-Altman plots were used to assess the differences between devices.

Results: Spherical equivalent values were found to be reproducible between standard and experimental autorefraction devices (intraclass correlation coefficient (ICC) > 0.8) in both low-vision and normally sighted groups. Similarly, manifest refraction was highly consistent (ICC > 0.8) between devices in all groups. The Bland-Altman plots showed clinically acceptable mean differences of 0.701 between autorefraction methods and -0.116 between manifest refraction methods.

Discussion: The 2WIN/VisionFit system can reliably generate refraction values across a spectrum of errors in normally sighted and visually impaired people, and would be feasible to deliver remotely.