A first for WPW: we noticed on Harrison's lens the word “Prizm,” so we looked it up. These are a new performance lens from Oakley. According to Oakley:
Prizm™ is a revolutionary lens technology that dramatically enhances contrast and visibility over a wide range of light conditions.
As far as baseball specific, Oakley is offering both infield lenses and outfield lenses. If you're curious, it would be wise to check out the link, then click one of the models, as there is more specific information at Oakley's website.
For what its worth, Harrison was wearing these during afternoon BP.