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Development of Vernier Acuity in Childhood.

CARKEET, ANDREW PhD; LEVI, DENNIS M. PhD, FAAO; MANNY, RUTH E. OD, PhD, FAAO
Optometry & Vision Science:
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Abstract

Purpose: To measure Vernier acuity and resolution development after 3 years of age.

Methods: Observers were 39 children with normal vision (aged 3 to 12 years), 10 adult observers with normal vision (aged 19 to 24 years), and 7 adults with amblyopia. Vernier acuity and resolution were measured using uncrowded static stimuli and a 3AFC psychophysical paradigm. Curve fitting was used to estimate A2, the age at which thresholds are twice asymptotic levels.

Results: Vernier acuity was hyperacute (i.e., finer than predicted from foveal cone size or spacing) in 3- to 4-year-old observers, but developed later (A2=5.6 +/- 1.5 years) than resolution acuity (A2=2.2 +/- 0.9 years).

Conclusions: Children's Vernier thresholds are poorer than would be predicted solely from their decreased foveal photon capture. Therefore cortical immaturity may play a role in children's relative position acuity deficit. R/V ratios (resolution/Vernier thresholds) for the youngest age group are similar to those for adult nonstrabismic amblyopes, but better than for strabismic amblyopes.

(C) 1997 American Academy of Optometry