Abstract
PURPOSE: To evaluate the viability and accuracy of a mobile application (app) for subjective measurement of presbyopic addition, comparing its performance with standard clinical methods. METHODS: Twenty presbyopic subjects (aged 52 to 64) participated in the study. Clinical measurements of sphero-cylindrical refraction and its correction was achieved using trial lenses. Addition was also clinically measured using a standard and a tentative method. A set of 12 trial lenses ranging from 0 to 2.75 D were randomly put on top of the far distance correction, generating the correction addition correction or different levels of under/over correction of the addition. Participants then used a smartphone-based app to subjectively determine binocularly their near point (NP) using a push-up method while looking at a blue stimulus that rescaled as a function of the face-device distance measured using the front camera of the device. For each induced level of under/over correction of the addition, participants completed three measurements of their near point. RESULTS: Linear regression analysis showed a strong correlation (R² = 0.82) between app-measured and clinical addition values. Bland-Altman analysis revealed a mean over estimation of -0.22± 0.38 D with a limit of agreement of ±0.74 D of the near correction. Cumulative error analysis indicated that 61.7 % of app measurements were within 0.25 D of clinical values, and 82.5 % within 0.50 D CONCLUSIONS: A smartphone-based subjective measurement of presbyopic addition can potentially be used to assess the addition needed to detect the under or over corrected addition in full presbyopic subjects.