Myopia Prescription Based on Smartphone App: A Feasibility Study in Africa

Uncorrected refractive error (URE) is the leading cause of vision impairment, especially in rural, underserved areas. We previously evaluated the accuracy of a smartphone app for measuring spherical equivalent refraction. In this study, we evaluated the benefits of vision correction based on the prescription given by the app.

The app estimates myopic refractive error by measuring the far point distances for reading 20/20 Tumbling E letters. Trial lenses rounded to 0.25 diopter (D) were fitted to 100 patients (myopic refractive error, astigmatism < 1.5 D) visiting MCM Eye Unit in Addis Ababa, Ethiopia. The age range of the participants was 10 to 68 years (mean = 31.3 ± 13.0 years). The refraction measurement and visual acuity (VA) tests were all performed without cycloplegia.

The range of spherical equivalent refractive error was -0.5 D to -6 D (interquartile range [IQR] = -2.25 D to -0.95 D), and the range of astigmatism was 0 to -1.25 D (IQR = -0.5 D to 0 D), according to subjective refraction performed by a study optometrist. On average, the uncorrected VA of the 200 eyes was 0.57 ± 0.32 logMAR. With the spherical equivalent correction based on the refraction app, their VA was improved significantly to 0.03 ± 0.09 logMAR-more than 5 lines of improvement, on average.

This study indicates that using the app to determine the spherical equivalent prescription for vision correction addresses the URE problem, whereas its effect for prominent astigmatism is yet to be evaluated.

This approach, which requires minimal training, has potential in fighting avoidable blindness in underserved areas lacking optometry services, such as remote Sub-Saharan Africa.