Comparison of grating and vernier acuity in infants with developmental delay

Background: Grating acuity measured by Teller cards is mildly reduced in children with developmental delay. Vernier acuity, the ability to detect offsets, also can be measured, but has not been studied in children with developmental delay. Methods: In a prospective cross-sectional pilot study, 12 nonverbal children with developmental delay established by pediatric assessment of developmental milestones were tested binocularly with vernier and Teller cards. Ages ranged from 4 to 24 months,Vernier offsets ranged from 2 to 64 minutes of are. Results: All children were testable with Teller acuity cards. Binocular grating acuity ranged from 1.7 to 7.4 cpd (median, 1.0 octaves below normal). Binocular vernier acuity ranged from unrecordable to 8 minutes of are (median, ''unrecordable''). Only four of the 12 children demonstrated a measurable vernier acuity. Normal children of this age have a vernier acuity of 2 to 16 minutes of are measured by this technique. Conclusion: The response to vernier acuity cards appears to be more severely degraded by developmental delay than the response to Teller cards.