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Updated: Jun 8, 2026
Using an Automated Hirschberg Test App to Evaluate Ocular Alignment
Published on: March 24, 2020
An automated Hirschberg test for infants
1Department of Electrical and Computer Engineering,University of Toronto, Toronto, ON M5S 3G4, Canada. dmitri.model@utoronto.ca
Insights
A new automated method accurately measures infant eye misalignment using Hirschberg ratio and angle Kappa. This technique offers reliable, objective assessment for pediatric eye conditions.
Area of Science:
- Ophthalmology
- Pediatric Medicine
- Biomedical Engineering
Background:
- Infant eye misalignment, such as strabismus, requires accurate and objective measurement for timely diagnosis and treatment.
- Current methods for assessing eye alignment in infants can be subjective and time-consuming.
- Objective quantification of ocular alignment parameters is crucial for understanding visual development.
Purpose of the Study:
- To introduce and validate a novel automated method for measuring eye misalignment in infants.
- To determine the accuracy and reliability of the automated method using key ocular parameters.
- To establish objective metrics for assessing infant eye alignment.
Main Methods:
- An automated system was developed to estimate the Hirschberg ratio (HR) and angle Kappa (κ) from sequential image presentations.
- Measurements included optical axis direction, pupil center coordinates, and corneal reflexes in each eye.
- Angle Kappa was determined by the peak distribution during image viewing; HR was calculated from the optical axis direction relative to pupil-corneal reflex distance.
Main Results:
- The automated method demonstrated high reliability for angle Kappa measurements, with 95% limits of agreement of ±0.61°.
- In orthotropic infants, the maximum error in eye alignment estimation was 0.9°, with 95% limits of agreement of 0.75°.
- The system successfully automated the estimation of critical parameters for eye misalignment assessment.
Conclusions:
- The novel automated method provides an accurate and reproducible means to measure eye misalignment in infants.
- This technique has the potential to improve the objective assessment of pediatric eye alignment.
- Further validation in larger infant cohorts is warranted to confirm clinical utility.
Abstract:
A novel automated method to measure eye misalignment in infants is presented. The method uses estimates of the Hirschberg ratio (HR) and angle Kappa (the angle between the visual and optical axis) for each infant to calculate the angle of eye misalignment. The HR and angle Kappa are estimated automatically from measurements of the direction of the optical axis and the coordinates of the center of the entrance pupil and corneal reflexes in each eye when infants look at a set of images that are presented sequentially on a computer monitor. The HR is determined by the slope of the line that describes the direction of the optical axis as a function of the distance between the center of the entrance pupil and the corneal reflexes. The peak of the distribution of possible angles Kappa during the image presentation determines the value of angle Kappa. Experiments with five infants showed that the 95% limits of agreement between repeated measurements of angle Kappa are ± 0.61 (°). The maximum error in the estimation of eye alignment in orthotropic infants was 0.9 (°) with 95% limits of agreement between repeated measurements of 0.75 (°).
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