Assessment of visual acuity in children with trisomy 18

Although 90% of children with trisomy 18 (Edwards syndrome) die in the first year of life, a small proportion survive into the second and third decade. Many do not have associated ocular abnormalities that might affect vision. Measurable visual acuity has not been reported in these profoundly developmentally delayed individuals. Five children with trisomy 18, aged six months to eight years, underwent complete eye examination including assessment of binocular grating acuity with Teller acuity cards and assessment of binocular vernier acuity with vernier cards. All children were nonverbal with profound developmental delay. Binocular grating acuity ranged from 0.9 cycles per degree (cpd) to 2.2 cpd. This represents a reduction of 1.9 to 5.1 octaves (mean 3.5 octaves, SD 1.3 octaves) compared to age matched norms. None of the children responded to any of the vernier offsets, including the largest of 64 minutes of arc. All children with trisomy 18 demonstrated a measurable grating acuity that was well below normal for age, consistent with profound developmental delay.