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The authors conducted pattern reversal visual evoked potential (PRVEP) in children with congenital Zika syndrome (CZS) and report the correlates with visual acuity, fundus alterations and severity of microcephaly at birth. This was a cross-sectional study of 37 children with CZS (14 male, 23 female) and 15 controls aged (mean) 18.5 ±0.9 months and 24.3 ±1.6 months respectively. For the CZS group, mean gestational age was 37.6 ±2.2 weeks and mean cephalic perimeter at birth was 28.6 ±1.8cms. At birth, 33 of 37 children were diagnosed with microcephaly; 24 of severe form. All had visual impairment confirmed. Visual acuity ranged from 4.8 cycles/cm to light perception. Ocular manifestations were recorded for 25, fundus findings for 24 and one had unilateral congenital cataract and microphthalmia. Twenty children were affected bilaterally. Retinal changes included chorioretinal atrophy (eight), pigment mottling (14) and discrete hypopigmented macular lesions (five). Optic nerve findings included pallor (nine), increased cup:disc ratio (seven) and hypoplasia (three). PRVEP was normal in seven, borderline in two, prolonger latency in 18 and undetectable in 10. All control children had normal findings. For children with CZS there was a positive correlation between P100 peak time and binocular logMAR visual acuity. For those without fundus abnormalities, the P100 peak was significantly worse than controls suggesting presence of visual impairment despite a structurally normal eye. There is potential for visual impairment to be due to neurological abnormalities with damage to central visual pathways and brain cortex. The authors conclude PRVEP is a useful tool for added assessment in CZS.

Pattern-reversal VEP in children with congenital Zika syndrome.
Almeida LFB, Kattah M, Ventura LO, et al.
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Fiona Rowe (Prof)

Institute of Population Health, University of Liverpool, UK.

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