Reduction of Rod and Cone Function in 6.5-Year-Old Children Born Extremely Preterm

Abstract

The function of rods and cones in children born extremely preterm has not yet been fully investigated.OBJECTIVE To compare retinal function via full-field electroretinographic (ffERG) recordings in 6.5-year-old children born extremely preterm with children born at term. DESIGN, SETTING, AND PARTICIPANTSA subcohort study was conducted from July 1, 2010, to January 15, 2014, of the national Extremely Preterm Infants in Sweden Study, including preterm children (<27 weeks' gestational age) and children born at term, at 6.5 years of age and living in the Uppsala health care region in Sweden. Full-field electroretinography was performed binocularly, using DTL electrodes and electroretinographic (ERG) protocols with flash strengths of 0.009, 0.17, 3.0, and 12.0 candelas (cd)/s/m 2 , together with 30-Hz flicker and 3.0 cd/s/m 2 single-cone flash. MAIN OUTCOMES AND MEASURESThe ffERG recordings were analyzed, and their associations with gestational age and retinopathy of prematurity were examined.RESULTS Adequate ffERG recordings were obtained from 52 preterm children (19 girls and 33 boys; mean [SD] age at examination, 6.6 [0.1] years) and 45 children born at term (22 girls and 23 boys; mean [SD] age at examination, 6.6 [0.1] years). Lower amplitudes of the combined rod and cone responses (the a-wave of the dark-adapted ERG protocol of 3.0 cd/s/m 2 : mean difference, -48.9 μV [95% CI, -80.0 to -17.9 μV]; P=.003; the a-wave of the dark-adapted ERG protocol of 12.0 cd/s/m 2 : mean difference, -55.7 μV [95% CI, -92.5 to -18.8 μV]; P = .004), as well as of the isolated cone response (30-Hz flicker ERG: mean difference, -12.1 μV [95% CI, -22.5 to -1.6 μV]; P = .03), were found in the preterm group in comparison with the group born at term. The implicit time of the combined rod and cone responses (the a-wave of the dark-adapted ERG protocol of 12.0 cd/s/m 2 ) was longer (mean difference, 1.2 milliseconds [95% CI, 0.3-2.0 milliseconds]; P = .01) in the preterm group, as were the isolated cone responses (30-Hz flicker ERG: mean difference, 1.2 milliseconds [95% CI, 0.5-1.8 milliseconds]; P < .001), than in the group born at term. No association was found between the ffERG recordings and gestational age or retinopathy of prematurity in the preterm group. CONCLUSIONS AND RELEVANCEBoth rod function and cone function were reduced in children born extremely preterm when compared with children born at term. There was no association with retinopathy of prematurity in the preterm group, which suggests that being born extremely preterm may be one of the main reasons for a general retinal dysfunction.

Retinopathy of Prematurity: Evolving Treatment With Anti–Vascular Endothelial Growth Factor

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Visual function is reduced in young adults formerly born prematurely: a population-based study

“…If structural changes in the macular area as well as functional changes in rods and cones previously found in preterm children could be a reason for the reduction may only be speculated on. [25][26][27] Also, microstructural changes in the optic nerve and/or visual pathway might affect visual function. 28 Previous studies in adults with severe ROP in the neonatal period have shown long-term complications.…”

Targeted Knockdown of Overexpressed VEGFA or VEGF164 in Müller cells maintains retinal function by triggering different signaling mechanisms

“…The infants at greatest risk of severe ROP in the US are often extremely premature infants, born younger than 28 weeks gestational age and less than 1000 g birth weight. The Extremely Premature Infants in Sweden Study (EXPRESS) reported that infants under 28 weeks gestational age who never developed ROP still had reduced ERG function and vision at age 6.5 years 22 , 23 . These infants also may be the most vulnerable to the effects of VEGF inhibition, because as young, very premature infants, less neural development has occurred than in older premature infants who have already met some milestones.…”