Abstract
Introduction: :
Survival rates have increased dramatically for preterm infants due to medical advances with up to 50% of infants surviving at 24-25 weeks gestation (1).The presence of retinopathy of prematurity (ROP) and ophthalmic abnormalities is 23% to 50% in preterm survivors (2). Few studies have examined the effect of ROP on visual processing in preterm survivors at school age.
Purpose: :
The purpose of this study is to compare first and second order static and dynamic visual processing in preterm children with ROP to a preterm group who do not have ROP, and to full term controls.
Methods: :
Preterm birth cohorts were recruited from a regional Neonatal Follow-Up Clinic at the Children’s Hospital of Eastern Ontario. A total of 52 subjects (< 1700 grams; gestational age < 36 weeks) with ROP (Stage 1, 2 or 3) were recruited for Study Group 1; 24 subjects without ROP for Study Group 2; a control group of 52 subjects comprise Study Group 3. Children diagnosed with cerebral palsy, chromosomal abnormalities, blindness, major auditory impairment or severe cognitive impairment were excluded. As there was only a total of n=11 preterm subjects with ROP Stage 3, Zone 1, this severe ROP group (MA:10.4 years) was compared to a preterm no-ROP group (n=11; MA:10.0 years), and to controls (n=11;MA:10.2 years), all matched by gender and by age. First-order (luminance defined) and second-order(texture contrast defined) static and dynamic processing was assessed(3).
Results: :
Preterm subjects with ROP performed significantly worse than subjects without ROP on second-order static texture discrimination. No differences between these groups were seen in second-order dynamic motion discrimination.Conclusions:Because no significant differences between groups were seen in dynamic second- order perceptual processing, we conclude that the effect of ROP on perceptual processing appears to be operational at the retinal level in this cohort. However, further research using a larger study sample is needed.
References: :
1. El-Metwally et al.(2000). Survival and neonatal morbidity of the limits of viability in the mid 1990's: 22 to 25 weeks. Journal of Pediatrics, 137, 616-22.2. Cooke et al.(2004). Ophthalmic impairment at 7 years of age in children born very preterm. Archives of Disease in Child Fetal Neonatal Education, 89, F249.3. Allard, R. & Faubert, J. (2006). Same calculation efficiency but different internal noise for luminance and contrast-modulated stimuli detection. Journal of Vision, 6(4), 322-334, doi:10.1167/6.4.3.
Keywords: retinopathy of prematurity