Our Research
The Kay Picture Test was first developed based on research published in 19831 and 19842. For the first time, we could use the principles that underpinned standard letter charts to design recognisable picture optotypes for accurate visual acuity testing of pre-literate children.
Since then, research published in 2010, 2016 and 2020 has allowed us to refine the Kay Picture optotypes to improve standardisation, legibility, and clinical reliability. The introduction of optimally crowded single optotypes was a significant development and the research has supported its applicability with the youngest verbal children. This means earlier accurate testing for amblyopia and other childhood eye conditions.
Our research summary PDF highlights the key findings of the recognition, comparisons, validation, and age-related normative data published to date. The full research papers are referenced in the PDF as well.
1 Kay H. Br J Ophthalmol 1983 Feb;67(2):131-3
2 Kay H. Brit Orthopt J 1984; 41: 77-80
Validation Research for the Redesigned Kay Picture Test
In a comprehensive research study carried out by Liverpool University Directorate of Orthoptics and Vision Science and a number of clinical orthoptic departments across the UK and The Retina Foundation of the Southwest, USA, the Kay Picture Test was shown to be valid and repeatable within the limits of current gold standards with high testability.
Download the PDF for a summary of this research and two other research papers.
Normative Data for the redesigned Kay Picture Visual Acuity Test
This paper by Anna O’Connor and Ashli Milling provides visual acuity norms for children with no ocular abnormality or known development delay aged 20 and 57 months.
The Kay Picture Test shows a lower limit increase with age than HOTV and Lea Symbols, suggesting that Kay Pictures gives more consistent results in this age range.
Normative Data for the Kay Picture Linear Crowded Test
This small study provides visual acuity norms for children with no ocular abnormality or known development delay aged 36 to 65 months.
The results support the Kay Picture Test’s reliability and clinical utility for assessing visual acuity in preschool-aged children, and offer normative benchmarks for expected acuity and interocular differences in children without ocular abnormalities.
Contribute to our research
If you would like to add your own research-project data, conference poster, or published research references to provide additional information, please send an email to contact@kaypictures.co.uk or see our contact details for other ways to get in touch.
Shop for the Kay Picture Test
Kay Picture Test Screening Book
£88.00
Kay Picture Test Screening Chart
£37.00
Kay Picture Test Linear Crowded Book
£112.00
Kay Picture Test Single Crowded Book
£112.00
Kay Letter Test
£112.00
