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A Method to Quantify Visual Information Processing in Children Using Eye Tracking
Published on: July 9, 2016
Crowding ratio in young normally sighted children
Marjoke J Dekker1, Florine Pilon, Mieke M C Bijveld
1Bartiméus Institute for the Visually Impaired, Ophthalmology, Zeist, Netherlands. mdekker@bartimeus.nl
Insights
The crowding ratio (CR) in children aged 4-12 is typically below 2.0 for near vision and for distance vision after age six. A CR above 2.0 in older children may indicate visual impairment.
Area of Science:
- Ophthalmology
- Pediatric Optometry
- Vision Science
Background:
- The crowding ratio (CR) is a measure used in vision testing.
- Understanding normal CR values in children is crucial for identifying visual anomalies.
Purpose of the Study:
- To establish normative data for the crowding ratio (CR) in a pediatric population.
- To define reference values for CR in children aged 4-12 years.
Main Methods:
- The study involved 62 normally sighted primary school children aged 4-12 years.
- Crowding ratio was assessed for both distance and near vision using LEA symbol charts.
Main Results:
- The CR was significantly better (lower) for near vision compared to distance vision across all ages.
- For distance vision, the upper limit of normal CR was found to be less than 2.0 from the age of six.
- Near vision CR values were consistently below 2.0 for all participants.
Conclusions:
- The crowding ratio (CR) can be readily measured in school-aged children using standard vision tests.
- A CR exceeding 2.0 in children over six years old, especially for distance vision, is considered abnormal and warrants further investigation.
- Elevated CR values may be indicative of conditions such as cerebral visual impairment (CVI).
Purpose:
To determine normal values of the crowding ratio (CR) in children.
Methods:
Of 62 normally sighted primary school children aged 4-12 years old the CR was determined both for distance and near vision. The examinations were performed using commonly available test charts based on the LEA symbols.
Results:
At near, the CR was significantly better than at distance and for all ages <2.0. The upper limit of the CR at distance was <2.0 from age six.
Conclusion:
With commonly available tests the CR can easily be determined in school age children. For children >6 years of age, a CR > 2.0 (i.e. at least 3 lines difference between the result of a single optotype acuity test and a line acuity test) is suspicious and warrants further investigation. It may, for example, be a sign of cerebral visual impairment (CVI).
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