Background Street Medicine Phoenix, a medical outreach program advocating for unhoused individuals, is the first United States based program utilizing the USee global vision refraction kit (USee) to enhance vision care. Costing $5 per use, the USee can refract patients and provide eyewear within 15 minutes, avoiding delays associated with shipment times and patients lost to follow-up. Other more widely used forms of refraction, such as the portable PlenOptika autorefractor (PlenOptika), are more expensive and can only provide a prescription, which is usually paired with another modality of creating and distributing glasses. This two-step process leads to the delivery of glasses weeks after initial refraction, which is not optimal for a population in constant flux. We report on the USee’s effectiveness in improving visual acuity compared to the PlenOptika.

Methods This participation-based study first assessed patients' uncorrected refraction. Patients were then refracted using PlenOptika and USee devices. Applying the manual refraction prescription, USee corrective lenses were inserted into frames, and corrected visual acuity was rerecorded. 2x2 Factorial ANOVA, spilt plot design was used to compare before and after refraction visual acuity. Bland Altman assessed the difference in spheres obtained from both devices. In addition, patients whose visual acuity improved to at least 20/40 monocularly were recorded (the legal minimum for driving in Arizona).

Results 180 eyes in 90 patients with mean age of 51.50 ± 12.66 years underwent refraction utilizing each device. Primary outcome was change in visual acuity with use of the USee device. Visual acuity in LogMar before refraction was 0.713 (0.624 - 0.801) and visual acuity in LogMar after refraction was 0.322 (0.269 - 0.374), p< 0.001. Bland Altman showed minimal outliers. 76% of patients were refracted to within 20/40. Median VA improved from 20/80 to 20/30, a 4 Snellen line improvement. Before and after percentage of patients with the ability to drive was 35.9% and 79.2%, respectively.

Conclusion The USee provides refractive measurements similar to that from the PlenOptika and provides measurable improvement in visual acuity among patients, making it a viable, more expedient option for use in under-resourced populations. By increasing this population's ability to drive, the intervention enables more individual freedom and job opportunities. Refraction with instantaneous eyewear distribution significantly improves outcomes for transient populations in need of refractive improvement.