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Updated: May 2, 2026
Author Spotlight: An Automated Method for Assessing Visual Acuity in Infants and Toddlers Using an Eye-Tracking System
Published on: March 17, 2023
At-home visual acuity in children using a custom iPhone application compared with standardized in-office visual
Tawna L Roberts1, Erick D Bothun2, Yufeng Zhu3
1Spencer Center for Vision Research, Byers Eye Institute at Stanford University, Palo Alto, California, USA.
Insights
A new smartphone app shows good accuracy for measuring children's visual acuity (VA) at 20/40 or better, both at home and in the clinic. However, accuracy decreases for poorer vision (20/50 or worse), especially with at-home testing.
Area of Science:
- Ophthalmology
- Digital Health
- Pediatric Care
Background:
- Accurate visual acuity (VA) measurement is crucial for early detection of vision disorders in children.
- Traditional methods can be time-consuming and require specialized equipment, limiting accessibility for at-home monitoring.
- Smartphone applications offer a potential solution for convenient and accessible VA testing.
Purpose of the Study:
- To validate a custom smartphone application for measuring visual acuity (VA) in children.
- To assess the app's concordance with gold-standard VA measurement methods in both at-home and in-office settings.
- To evaluate the app's performance across different age groups and levels of visual acuity.
Main Methods:
- A study involving 452 children aged 3-17.5 years.
- Comparison of app-based VA measurements (at 1.5m) with gold-standard methods (HOTV and electronic ETDRS protocols at 3-4.5m).
- Measurements were taken both in-office by examiners and at-home by caregivers.
Main Results:
- The app demonstrated good concordance with gold-standard VA for eyes with 20/40 or better vision (93-98% within 2 lines).
- Concordance decreased for eyes with 20/50 or worse vision, with 66-75% agreement in the at-home setting.
- Test-retest reliability for the gold standard was high across all VA levels.
Conclusions:
- The validated smartphone app shows promise for at-home and in-office visual acuity assessment in children with good vision (20/40 or better).
- Performance is less reliable for children with poorer visual acuity (20/50 or worse), particularly in the at-home setting.
- Further refinement may be needed to improve accuracy for children with sub-optimal vision.
Purpose:
To validate a custom smartphone application for at-home visual acuity (VA) measurement in children.
Methods:
A total of 452 children aged 3-17.5 years participated. Certified examiners measured in-office test-retest VA (logMAR) using gold-standard Amblyopia Treatment Study HOTV (3-to-6-year-olds, younger cohort) or electronic Early Treatment of Diabetic Retinopathy Study (7-to-17.5-year-olds, older cohort) protocols at 3-4.5 m and app-based VA at 1.5 m. Caregivers measured at-home app-based VA at 1.5 m.
Results:
Comparing at-home app-based with gold-standard VA, in eyes 20/40 or better, 95% (143/151) and 93% (91/98) of the younger and older cohorts were within 2 lines, respectively (mean differences: younger = -0.03, older = -0.04; 95% limits-of-agreement half-width (LOA): younger = ±0.26, older = ±0.22). In eyes 20/50 or worse, 66% (42/64) and 75% (76/101) of the younger and older cohorts were within 2 lines, respectively (mean differences: younger = 0.11, older = 0.13, LOA: younger = ±0.50, older = ±0.51). Comparing in-office app-based VA with gold-standard VA, in eyes 20/40 or better, 98% (160/164) and 94% (99/105) of the younger and older cohorts were within 2 lines, respectively (mean differences: younger = -0.03, older = -0.03; LOA: younger = ±0.22; older = ±0.24). In eyes 20/50 or worse, 85% (60/71) and 91% (101/111) of the younger and older cohorts were within 2 lines, respectively (mean differences: younger = 0.04; older = 0.04; LOA: younger = ±0.39; older = ±0.24). For gold-standard test-retest, in eyes 20/40 or better, 99% (163/164) and 99% (104/105) of the younger and older cohorts had retest within 2 lines, respectively (mean differences: younger = 0.00; older = 0.01; LOA: younger = ±0.17; older = ±0.11). For 20/50 or worse, 92% (66/72) and 100% (111/111) in the younger and older cohorts were within 2 lines, respectively (mean differences: younger = 0.01; older = 0.02; LOA: younger = ±0.35; older = ±0.15).
Conclusions:
Our app demonstrated good concordance with the gold standard at home and in the office for eyes with VA of 20/40 or better. However, concordance decreased considerably for eyes with VA 20/50 or worse, particularly at home.
