Function of the visual pathway in preterm children at school age.

Abstract

Purpose : The morphology of the optic nerve head is affected in school-aged preterm children when compared to children born at term, but if the function is affected remains uncertain. In this case control study we used multifocal visual evoked potential (mfVEP) to test the function of the visual pathways in former preterm children and compare with results from healthy controls.

Methods : Method
We included 13 children, 4 boys and 9 girls, born before a gestational age (GA) of 32 weeks. Mean GA was 28.5 weeks and mean birthweight was 1213 g. Mean age at investigation was 13.0 years. Five of the preterm children did not have any retinopathy of prematurity (ROP) in the neonatal period and 8 children had ROP, included two children who were treated with laser. The control group included mfVEP results from 11 children, 1 boy and 10 girls, with mean age 12.6 years.
MfVEP was measured using the Visual Evoked Response Imaging System (VERIS). Three pairs of electrodes placed at defined locations at the back of the head. The stimuli consisted of 60 segments, each containing 16 reversing checkers. Registration was made in 16 periods of 27 second each.
The main outcome was the peak to peak amplitude from a defined central region (sector C), which is the area were the signal to noise ratio is highest and correlated to generalized dysfunction of the visual pathways. (M. Bengtsson et al. Clin Neurophysiol. 2005, L. Gränse et al. Ophthalmic Genet. 2003). Results from right eyes were used for analysis.

Results : The peak to peak amplitude of sector C in in the preterm group was median: 30.1 nV/deg² (range:16.1-39.5), and in the control group: median: 25.3 nV/deg² (range: 11.7-93.7). There was no significant difference between the groups. When dividing the preterm group into children with and without ROP in the neonatal period and compared with controls the result remained the same.

Conclusions : The function of the visual pathways measured with mfVEP was not reduced in the preterm children compared to controls. This is in line with earlier studies showing that the function in prematurely-born is delayed in the neonatal period but seem to catch up in the first year of life. The result of the present study indicates that the morphological changes in the optic nerve seen in former preterm children may not influence the function of the visual pathways in this group of children.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.