Two main risk factors associated with ocular findings encountered in infants with congenital Zika syndrome were identified in a Brazilian study, according to lead study author Camila V. Ventura, MD.
The first was symptoms referred by mothers in the first trimester of pregnancy, and the second was smaller cephalic diameter at birth.
“In other words, pregnant women that report symptoms during the first 3 months of gestation have a greater risk of having a baby with ocular findings, as well as babies born with very small head circumference have more chance of having retinal and optic nerve findings,” Ventura said.
Ventura said recent studies were able to explain in mice models how the virus causes microcephaly. The study results have reported that the virus crosses the placenta and attacks the cortical progenitor cells in the brain, causing cell death by apoptosis and autophagy, and stopping the brain’s growth and normal development. Furthermore, Ventura explained that early exposure to Zika virus during early development of the brain is directly related to severe microcephaly because the brain’s growth is affected in early stages of development.
“In fact, these two risk factors are intrinsically related to each other since exposure to the virus during the first trimester is related to severe microcephaly, exposure to the virus during the first trimester is related to the ocular findings, and the ocular findings are related to severe microcephaly,” she said.
This information is important because early identification of retinal and optic nerve lesions indicates early visual rehabilitation for the affected infants, she said.
Another milestone of this study was “to prove that the ocular findings seen in the babies are part of the [congenital Zika syndrome],” according to Ventura.
Researchers tested the cerebrospinal fluid of 24 of the 40 infants with microcephaly in the cross-sectional study and all 24 were found to have positive results for Zika virus infection. Fourteen of 22 infants with ophthalmoscopic findings and 10 of 18 infants without ophthalmoscopic findings were positive for the virus.
Ten mothers of infants with ocular findings reported experiencing Zika virus symptoms such as rash (65%), fever (22.5%), headache (22.5%) and arthralgia (20%) during the first trimester of pregnancy. No mothers reported conjunctivitis or other ocular symptoms during pregnancy, and none presented signs of uveitis during their examinations. – by Robert Linnehan
Ventura CV, et al. JAMA Ophthalmol. 2016;doi:10.1001/jamaophthalmol.2016.1784.
- For more information:
Camila V. Ventura, MD, can be reached at Bascom Palmer Eye Institute, 900 NW 17th St., Miami, FL 33136; email: email@example.com.
Disclosure: Ventura reports no relevant financial disclosures.