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Updated: Aug 2, 2026
A Method to Quantify Visual Information Processing in Children Using Eye Tracking
Published on: July 9, 2016
Visual acuity and pupillary responses to spatial structure in infants
K D Cocker1, M J Moseley, J G Bissenden
1Department of Ophthalmology, University of Birmingham, United Kingdom.
Insights
The pupil grating response (PGR), an objective measure of infant vision, is not present at birth but emerges by one month of age. This visual acuity assessment method correlates well with behavioral measures in infants.
Area of Science:
- Developmental neuroscience
- Infant vision research
- Ophthalmology
Background:
- Assessing visual acuity in infants is crucial for early detection of visual impairments.
- Objective measures are needed as behavioral assessments can be challenging in very young infants.
- The pupil grating response (PGR) offers a potential objective method for evaluating visual resolution.
Purpose of the Study:
- To determine the age of onset for the pupil grating response (PGR) in infants.
- To compare visual acuity estimates derived from pupillometry (PGR) with behavioral methods in early infancy.
Main Methods:
- Dynamic infrared pupillometry was used to measure pupillary responses in 19 newborn infants.
- Infants fixated a uniform background with brief presentations of sine wave gratings (0.1 c/deg).
- Longitudinal PGR measurements and behavioral acuity card procedures were conducted on a subset of eight infants.
Main Results:
- Newborn infants did not exhibit a PGR to pattern stimuli, despite intact pupillary light reflexes.
- Reliable PGRs were observed from one month of age onwards.
- The PGR's spatial frequency threshold closely matched behavioral resolution estimates in infants aged one month and older.
Conclusions:
- The pupil grating response (PGR) is not detectable in newborns.
- From one month of age, PGR provides objective visual acuity estimates comparable to established behavioral methods.
Purpose:
To determine the age of onset of the pupil grating response (PGR). To compare estimates of resolution acuity obtained by pupillometric and behavioral methods in early infancy.
Methods:
Dynamic infrared pupillometry was undertaken on 19 newborn infants while they fixated a uniform background upon which a 0.1 c/deg sine wave grating was briefly presented. Pupillary responses were also recorded to an increment in luminance of a spatially homogeneous target. Longitudinal measurements of PGRs were obtained from a subset of eight infants between 3.5 and 38 weeks of age. In this group, behavioral estimates of visual resolution obtained using the acuity card procedure were compared with the highest spatial frequency grating to elicit a PGR.
Results:
When presented with the pattern stimulus, newborn infants did not show any pupil reaction indicative of a PGR. This finding could not be attributed to immaturity of pupillomotor function: All infants showed marked pupillary construction to diffuse light stimulation. By 1 month of age, pupillary responses to pattern stimuli were reliably present. For these and older infants, the spatial frequency of the finest grating to elicit a PGR was comparable to the behaviorally determined resolution threshold: mean difference (+/- 95% confidence interval) = 0.28 +/- 0.23 octaves.
Conclusions:
A PGR could not be detected in newborn infants. From 1 month of age, responses to spatial structure can provide objective estimates of visual acuity comparable to those determined by established methods.
