By Robert Preidt
"All infants with potential Zika virus exposure should undergo screening eye examinations regardless of [central nervous system] abnormalities, timing of maternal infection during pregnancy, or laboratory confirmation," said Dr. Andrea Zin and colleagues. Zin is with the National Institute of Women's Health in Rio de Janeiro, Brazil.
In some cases, evidence of Zika infection may only show up in the eyes, the study found. The results were published July 17 in the journal JAMA Pediatrics.
"Eye abnormalities may be the only initial finding in congenital Zika virus infection," Zin said in a journal news release.
Zika, a mosquito-borne virus, usually causes only mild symptoms in healthy adults. But fetal exposure during pregnancy can result in serious birth defects, including microcephaly, an abnormally small head and brain.
The study included 112 infants in Brazil born to mothers with confirmed Zika infection. The infants were followed by a medical team for their first year of life.
The researchers found that 20 infants had microcephaly, 31 had other central nervous system abnormalities, and 61 had no central nervous system problems.
But one in five of the infants had sight-threatening eye abnormalities, with optic nerve and retinal abnormalities the most common, the investigators said.
Ten of those with eye problems did not have microcephaly and eight had no central nervous system findings.
The researchers noted, however, that they "cannot affirm with absolute certainty" that all of the eye abnormalities were caused by Zika virus infection.
In terms of timing, more than half of the infants with eye abnormalities were born to women infected with Zika virus in the first trimester. One-third were born to women infected with Zika virus in the second trimester, and two were exposed in the third trimester, according to the study.