Do picture-based charts overestimate visual acuity? Comparison of Kay Pictures, Lea Symbols, HOTV and Keeler logMAR charts with Sloan letters in adults and children.
OBJECTIVE
Children may be tested with a variety of visual acuity (VA) charts during their ophthalmic care and differences between charts can complicate the interpretation of VA measurements. This study compared VA measurements across four pediatric charts with Sloan letters and identified chart design features that contributed to inter-chart differences in VA.


METHODS
VA was determined for right eyes of 25 adults and 17 children (4-9 years of age) using Crowded Kay Pictures, Crowded linear Lea Symbols, Crowded Keeler logMAR, Crowded HOTV and Early Treatment of Diabetic Retinopathy Study (ETDRS) charts in focused and defocused (+1.00 DS optical blur) conditions. In a separate group of 25 adults, we compared the VA from individual Kay Picture optotypes with uncrowded Landolt C VA measurements.


RESULTS
Crowded Kay Pictures generated significantly better VA measurements than all other charts in both adults and children (p < 0.001; 0.15 to 0.30 logMAR). No significant differences were found between other charts in adult participants; children achieved significantly poorer VA measurements on the ETDRS chart compared with pediatric acuity tests. All Kay Pictures optotypes produced better VA (p < 0.001), varying from -0.38 ± 0.13 logMAR (apple) to -0.57 ± 0.10 logMAR (duck), than the reference Landolt C task (mean VA -0.19 ± 0.08 logMAR).


CONCLUSIONS
Kay Pictures over-estimated VA in all participants. Variability between Kay Pictures optotypes suggests that shape cues aid in optotype determination. Other pediatric charts offer more comparable VA measures and should be used for children likely to progress to letter charts.
School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand.
Nicola S
http://orcid.org/0000-0003-1999-5274
NS
Anstice
School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand.
Robert J
RJ
Jacobs
School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand.
Samantha K
SK
Simkin
School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand.
Melissa
M
Thomson
School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand.|School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada.
Benjamin
B
Thompson
School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand.
Andrew V
AV
Collins
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D006801:Humans; D008875:Middle Aged; D015203:Reproducibility of Results; D014786:Vision Disorders / Q000175:diagnosis; D014787:Vision Tests / Q000379:methods*; D014792:Visual Acuity; D055815:Young Adult