Abstract
Purpose: :
Children born very preterm have an increased risk of developing neuromotor and perceptual disabilities. The aim of this project was to study the development of visual perception and to try to find predictive methods for early detection of deficiencies.
Methods: :
A prospective longitudinal study of infants born without malformations in Uppsala County at a gestational age (GA) < 32 weeks, with a planned sample size of 100, was initiated. Cranial ultrasound was performed at 3–7 days postnatally and at 35 weeks postmenstrual ages (PMA). Screening for retinopathy of prematurity (ROP) was performed weekly from 5 weeks postnatally until around PMA of 40 weeks. A neonatologist and a physiotherapist assessed the children’s neuromotor development. Visual motion perception was studied at 2 and 4 months corrected age, using electrooculography (EOG) and an optoelectronic system. The infants tracked a small moving object (a happy face) and the eye–and head movements were registered. The smooth pursuit gain was defined as the calibrated eye movement after the elimination of saccades. This method has previously been used to study the early development of smooth pursuit movements in full–term healthy infants, now serving as a control group (n=28). To our knowledge, this is the first time the method has been used in prematurely born infants.
Results: :
The results of the first 25 prematurely born infants (mean GA 27+3 weeks and mean birth weight 1397 gram) in our prospective study are presented. The mean value of the smooth pursuit gain in the prematurely born infants (0.24, SD 0.14 at 2 months and 0.41, SD 0.21 at 4 months) was significantly lower than in the control group (0.56, SD 0.18 at 2 months and 0.79, SD 0.10 at 4 months). A significant improvement of the gain between measurements at 2 and 4 months was seen in both groups (p<0.01 in the premature group and p<0.0001 in the normal group).
Conclusions: :
Our preliminary findings indicate that a deficient smooth pursuit gain is seen at 2 and 4 months corrected age in infants born very preterm compared to children born at term. There is, however, an improvement in the gain between 2 and 4 months in respective groups. The delayed development of smooth eye movements in the prematurely born infants might be a help for early detection of impaired visual perception.
Keywords: visual development: infancy and childhood • eye movements: saccades and pursuits