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Cataracts and the Zika Virus Affect Vision Development

Posted by Ilena Di Toro | Posted on February 16, 2021

When babies are born, they can see an object with their peripheral vision but their central vision is still developing. Over the first few weeks, as a baby’s retina develops, his or her pupils widen and the baby can see light and dark ranges and patterns. At one month, a baby may briefly focus on a parent or caregiver, but they are mostly interested in objects that are very close to them.

Of course, things can get in the way of normal vision development. They include cataracts and the Zika virus.

Children and infants can have cataracts. When a baby is born with a cataract, it is known as a congenital cataract. If a cataract forms within the baby’s first six months of life, it is an infantile cataract. However, the cataract forms, children who have their cataracts removed are at risk for developing glaucoma. A study funded by the National Eye Institute (NEI) found that children who have cataract surgery as infants, have a 22 percent chance of developing glaucoma 10 years later, regardless of receiving an intraocular lens implant.

This study involved 114 babies between the ages of 1 to 6 months who had been born with a cataract in one eye. They were randomly assigned to receive an artificial lens or go without a lens, which is called aphakia. The idea behind placing a lens in the baby’s eye is to allow the eye to focus light properly. If a lens isn’t implanted, contacts or glasses, if both eyes have cataracts removed, will be utilized to provide vision correction.

While implanting a lens in an infant seems like a good idea, the problem is figuring out the power that the child will need. So, an estimation is done, which may or may not be correct. Scientists think that the surgery interferes with the maturation process of how fluid goes out of the eye. This leads to increased eye pressure and, subsequently, optic nerve damage.

Of the 110 children who were available for re-examination at the 10-year mark, 24 percent developed glaucoma and 20 percent had elevated eye pressure, making them glaucoma suspect. Despite these developments, visual acuity was similar in each group and there was no glaucoma-related eye damage. Researchers credit the lack of glaucoma-related eye damage to patient monitoring since any sign of glaucoma was aggressively treated.

The study shows that the timing of the surgery is important. Surgery at a young age increases the risk of glaucoma. Delaying surgery increases risk of amblyopia. So, the good thing about this study is that it defines diagnostic standards for pediatric glaucoma and related conditions for patients around the world.

Zika Virus
Remember when the Zika virus was the virus celebre in 2016? Despite the focus of the coronavirus in 2020, researchers are continuing to study this virus. One thing scientists are studying is the Zika virus’ effect on vision, in particular how it affects eye development. A study done in collaboration with the University of California Davis Eye Center and the California National Primate Research Center learned that getting Zika infection during the first three months of pregnancy can impact retinal development and cause congenital ocular anomalies. Yet, it doesn’t affect ocular growth after birth.

Two pregnant rhesus monkeys were infected with Zika virus late in their first trimester. The ocular development of their offspring was studied for two years. While the offspring didn’t have neurological or behavioral defects, they did have several ocular birth defects. This included a large colobomas, a missing gap in the eye due to abnormal development, loss of photoreceptors and the retinal ganglion neuron, which transmits visual information to the brain. Yet, despite all these defects, the eyes of the offspring did follow normal development during their first two years of life. This suggests that the defects as a result of the Zika infection occur in utero and don’t have a continued impact on ocular development after birth.

Vision development doesn’t always follow a straight line. Thanks to research, the crooked line can be made straight or at least people can learn where the detour begins.


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