Zika Virus May Be Linked to Infant Eye Abnormalities, Study Says

— -- The Zika virus may be associated with another birth defect in infants, according to a new study published today in the Journal of the American Medical Association Ophthalmology.

Researchers from Brazil found that some infants exposed to the virus had ocular defects including atrophied retinas, abnormal iris pigmentation and lens that moved out of place.

The Zika virus has spread exponentially across the Americas, and especially in Brazil, since the outbreak was identified in May 2015. Brazil was the first to raise the alarm that the virus could be linked to a rare birth defect called microcephaly, characterized by an abnormally small head and brain in infants.

This study is the first to possibly connect the virus to eye abnormalities in newborns.

Researchers focused on 29 infants with microcephaly in Brazil. They found that 23 mothers reported Zika-like symptoms during their pregnancy. Of the affected infants, 10 had ocular abnormalities that ranged from minor to "vision-threatening" defects. Both eyes were affected in seven out of the 10 infants.

The most common defects were mottled pigments and atrophy. The optic nerve was also found to be abnormal in some of the infants.

Dr. Buddy Creech, an associate professor of Pediatric Infectious Diseases at Vanderbilt University Medical Center, said other viruses, including herpes and rubella, are known to cause ocular birth defects in infants.

"This idea of a virus contracted during pregnancy causing damage to the central nervous system is not a shocking finding," Creech said.

Although the case study was small, Creech said these kinds of investigations will be key to uncovering how the Zika virus works and where there are "windows of risk" for pregnant women.

"We’re learning about this virus and we don’t know what to expect," said Creech. "We need papers like this that give us ability to move further down the road."

The researchers said they could not definitively link the ocular defects to the Zika virus until there were more studies to rule out that the ocular lesions were not caused by other diseases including West Nile or toxoplasmosis.

ABC News' Chief Health and Medical Editor Dr. Richard Besser said this early study highlighted concerns that there could be an unknown "spectrum" of effects related to the Zika virus.

“One of the reasons that CDC wants to create a registry of potentially exposed pregnant women is the recognition that for most infections that can damage the fetus, there is a spectrum of effects," said Besser, adding that rubella can also cause hearing loss and visual problems even if microcephaly does not develop. "Microcephaly may just be the tip of the iceberg.”