The first instances of Zika virus infection were noted in Brazil two years ago. As of today, it is estimated that there are over one million people in Brazil that are infected. Infected indiviuals are also present in other South American and Caribbean nations.
The Zika virus is transmitted through mosquito bites. The mosquito is present across most of the southern United States, but not to any great degree in Califonia. So the chance for acquiring this infection in California should be very low. Of greatest concern in the United States is the Gulf region.
The virus causes problems in the unborn children of women who are infected. It affects the nervous system and can cause severe mental retardation. The retina and optic nerve of the eye are composed of nervous tissue, and unfortunately, the Zika virus does affect these tissues. It is too soon to know for sure what effects this damage will have on vision, but the retina and optic nerve are critical to sharp vision, so some of these infected children may have severe vision issues.