Scientists have found previously unreported eye problems in babies with Zika virus-related birth defects which could result in severe visual impairment. In three Brazilian infants with microcephaly, the researchers from Stanford University in the US and colleagues observed retinal lesions, hemorrhaging and abnormal blood vessel development not noted before in relation to the virus.
Zika virus is now known to cause microcephaly, a birth defect marked by smaller head and brain size. In Brazil, the site of the most serious outbreak, nearly 1.5 million people reportedly have the virus.
Some 4,000 infants were recently born with microcephaly, researchers said. As a result, the World Health Organisation (WHO) declared a public health emergency in February this year, bringing added urgency to the need for more research.
A prior study of 29 Brazilian babies with presumed congenital Zika infection showed that a third had eye problems. These included ocular lesions, optic nerve abnormalities and chorioretinal atrophy, a withering of the retina and choroid, the latter of which provides oxygen and nutrients to the retina.
For this case study, researchers examined the eyes of three infant boys from Northern Brazil born in late 2015 with microcephaly. All had mothers with suspected Zika virus infections during the first trimester of pregnancy.
Researchers identified several types of ocular issues not previously observed in relation to Zika virus, some of which could cause visual impairment if untreated. These included bleeding and signs of missing blood vessels in the retina, and torpedo-shaped lesions in the macula, the central portion of the retina.
In addition to these observations, the infants exhibited other ocular symptoms noted in the previous study. All three babies in this case study showed signs of pigmentary maculopathy, lesions that appear as speckles of pigment on the macula. Four eyes had symptoms of chorioretinal atrophy marked by a darkly pigmented ring.
The findings add to a growing body of clinical information about how the Zika virus may affect children’s eye development and vision. The researchers noted that it remains unclear whether the viral infection itself causes eye abnormalities or if they are a consequence of Zika-induced microcephaly.
“To my knowledge, the eye problems we found have not been associated with Zika virus before,” said Darius Moshfeghi, a professor at the Stanford University School of Medicine. “The next step is to differentiate what findings are related to the Zika virus itself versus microcephaly caused by the virus in order to better understand which infants will need screening,” Moshfeghi said. The findings appear in the journal Ophthalmology.