Preliminary evaluation of smartphone-based addition measurement in a presbyopic population

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.