The mosquito-borne virus is linked to new and potentially vision-robbing eye conditions in infants.
Researchers have found babies born to women infected with the Zika virus are at risk for microcephaly, a birth defect marked by a smaller than normal head and varying degrees of neurological problems. And now there’s mounting evidence babies born with Zika-linked microcephaly may also suffer from conditions that can destroy vision.
In a study of 29 Brazilian babies born with microcephaly as the result of congenital Zika infection, over a third had serious eye disorders; both eyes were affected in 70 percent of the infants. The vision-threatening conditions found by the team of Brazilian and U.S. researchers included ocular lesions and optic nerve abnormalities. About 65 percent of the infants had a condition called chorioretinal atrophy that causes the retina (the light-sensitive layer of tissue at the back of the eyeball) and choroid (the layer of blood vessels and connective tissue in the eye that provides oxygen and nutrients to the retina) to wither.
Now ophthalmology researchers from Brazil and Stanford University have found even more eye problems in babies exposed to Zika virus before birth. The research team studied the eyes of three infant boys with microcephaly who were born in Brazil to mothers with suspected Zika infections. The babies had some of the same Zika-associated eye conditions identified in earlier research — all three showed signs of lesions in the central part of their eyes (the macula) and four eyes had signs of chorioretinal atrophy.
But three additional and serious ocular issues that had never been associated with Zika virus before were also spotted:
- Hemorrhagic retinopathy (bleeding in the retina).
- Abnormal blood vessels in the retina — including evidence of missing blood vessels where cells likely died.
- Torpedo-shaped lesions in the central part of the retina (the macula). Other types of retinal lesions had been reported before in Zika-association ocular findings, but this type of lesion, known as torpedo maculopathy, had not been previously identified in babies with microcephaly.
While the latest study involves only three children, it’s another piece in the growing puzzle of how Zika may impact both eye development and vision.
“The next step is to differentiate what (ocular) findings are related to the Zika virus itself versus microcephaly caused by the virus in order to better understand which infants will need screening,” said Zika researcher Darius Moshfeghi, MD, a professor of ophthalmology at the Stanford University School of Medicine.
Lee M Jampol, MD, who is studying Zika infection and the eye, thinks it’s highly unlikely microcephaly, which is not a disease but a physical finding resulting from neurodegeneration of the brain, is sparking the eye problems associated with Zika. Instead, he suggests the ocular conditions may be a direct effect of the virus.
“Until Zika is isolated from the eye, as was done with Ebola virus, we will not be certain that the virus has actually invaded the eye,”Jampol, a professor of ophthalmology at Northwestern University, wrote in JAMA Ophthalmology. ”However, we doubt that the physical finding of microcephaly itself was the cause of the observed ocular abnormalities.”
All of the eye conditions found so far in many infants with Zika-linked microcephaly can cause severe visual impairment if not treated. To identify ocular problems in at-risk infants, the American Academy of Ophthalmology and the Centers for Disease Control and Prevention recommend babies born with possible congenital Zika virus infection receive an eye examination, including a retina evaluation, either in the hospital or within one month after birth.
June 20, 2016