Related Experiment Video
Updated: Nov 20, 2025
Subjective Refraction Test Using a Smartphone for Vision Screening
Published on: October 18, 2024
Influence of Reading on Smartphone Screens on Visual Optical Quality Metrics and Tear Film Stability
Emmanuel Bettach1,2, David Zadok1,2, Adi Abulafia1,2
1Department of Ophthalmology, Shaare Zedek Medical Center, Jerusalem, Israel; Affiliated with the Hebrew University of Jerusalem; and.
Purpose:
To evaluate the impact of a prolonged reading session on a smartphone screen on optical quality metrics and tear film stability.
Methods:
This prospective study was conducted in 41 healthy volunteers who were asked to read an article on a smartphone screen for 20 minutes. The following tests were performed before the reading task in this consecutive order and repeated after the reading task in the same order: automated noninvasive tear break-up time, optical quality assessment including Objective Scatter Index (OSI), modulation transfer function, Strehl ratio, and tear film dynamic analysis as follows: vision break-up time (VBUT) as a function of OSI changes within 20 seconds, using a double-pass aberrometer imaging system, and fluorescein tear break-up time (FBUT) measured using the slit lamp.
Results:
All break-up time-related parameters (noninvasive tear break-up time, FBUT and VBUT) were significantly reduced after the reading task (P < 0.01). The OSI was significantly worsened after the reading task (P = 0.01), whereas all the other optical quality metrics (modulation transfer function and Strehl ratio) slightly deteriorated, were not statistically significant. A significant correlation was found between the shortening of the FBUT, VBUT, and the worsening of the OSI (r = -0.33, P < 0.05).
Conclusions:
A reading session on a smartphone screen in healthy subjects was found to significantly affect the tear film stability and objectively worsen the retinal image quality.
