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JM Miller, EM Harvey, V Dobson; A Practical Method for Testing Vernier Acuity in Children . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2665.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: A method for testing vernier acuity using stimuli printed on a LaserJet Printer is described. Stimuli can be presented at reasonable test distances (1.75 meters) with very small offsets (5 seconds of arc per LaserJet dot). The stimuli can be printed with the vernier offset along any orientation, allowing for the detection of meridional differences in vernier acuity. Methods: Subjects were 114 children in grades K-8 who attend school on the Tohono O'Odham Reservation. Children were tested while wearing best correction, determined by cycloplegic refraction with refinement. On each trial a vernier offset (from 5 to 120 arc seconds) is present in 1 of 3 bars shown. The child is asked to indicate which bar is different. A pretest is used to first estimate threshold, followed by multiple trials at increasingly smaller offsets. Threshold is taken as the smallest vernier offset where the child correctly identifies the vernier stimulus on 3 of 4 trials. Results: The procedure could be performed by 112 of 114 children. Most (84%) demonstrated hyperacuity, having Horizontal Offset vernier acuity thresholds greater than 30 seconds arc. Subjects were fairly well distributed in their vernier response within this range, with 14% showing 5 arcsec, 35% with 10 arcsec, 18% with 15 arcsec , 9% with 20 arcsec, and 8% with 25 arcsec vernier acuity. Conclusion: Use of small-offset stimuli printed with a LaserJet allow both small vernier offsets and reasonable test distances. A test book can be prepared that allows rapid staircase presentations of vernier stimuli without the need for a computer. The test is readily accepted by young children, and provides a rapid and sensitive method for the estimation of orientation-specific vernier acuity.
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