Abstract
Purpose: :
The aim of this study is to examine the retinal function with full-field electroretinography (ERG) in prematurely born children and compare with children born at term.
Methods: :
Children born before 33 weeks of gestation in Uppsala County, Sweden, were included in the study. They had all been screened for ROP at Uppsala University hospital. Children born at term with normal birthweights, visual acuity and refraction acted as control group.Full-field ERG was done after dilatation of the pupils. Stimulations were performed according to International Society for Clinical Electrophysiology of Vision (ISCEV) standards and included photopic rod response, photopic combined rod-cone response and scotopic cone response.
Results: :
Preliminary results from the right eyes of 20 preterm and 15 fullterm children are presented. Eight of the prematurely born children had ROP in the neonatal period. Mean age at investigation was 11.8 years (range: 6.3-17.4). The preterm children had lower amplitude of the a-wave in the photopic rod-cone response (flash intensity: 12 cd.s/m2), median: -257,9 µV, than the control children; median: -312.7 µV, (p=0.007). This difference remains when comparing the preterm children without previous ROP with the control group, (p=0.03), but there was no correlation with gestational age. The scotopic cone response, 30 Hz flicker, had a significantly reduced peak amplitude in the preterm group, median: 62.3 µV, compared to the controls, median: 86.4 (p=0.007). There was no significant difference in implicit times in any of the responses.
Conclusions: :
The a-wave in the full-field ERG reflects the photoreceptor function and the amplitude of the 30 Hz flicker, the function of the cone system. The retinal development starts early after conception and continues long after birth. Although all retinal cells are present at midgestation, the photoreceptors are still very immature when the preterm children are born. The preliminary results of this study indicates that the photoreceptors are affected by the preterm birth.
Keywords: electrophysiology: clinical • retina • retinal development