You would have to replace to entire back to get it repaired with google/a repair shop, which is expensive. But you could DIY it for a lot cheaper.
Follow these instructions up until putting a glass protector on the whole visor: [guide|156439]
Then, you can get something like this from ebay (or whatever is best for you) and stick it on: https://www.ebay.com/itm/304923625458
Hope this helps.