I'm 29 yo female living in Japan.
I have port wine stain surrounding my right eye, and started using covermark's concealer in highschool, but it was always heavy, and
I hate it after a long day, my face started cracking....
I now use Shiseido's Perfect Cover. The product claims they focused on light ray's characteristic, that when mixed with complementary color(for red, is green), the red color diminishes(supposedly
(sorry, in japanese..)
I'm not quite sure how it works, but with light application, my red mark
is covered, and my friends didn't notice my birthmark until I told them I had.(I have birthmark covering whole right eye, and some cheek) It looks very natural.
Just to introduce what a person who has birthmark from other country is using